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HomeMy WebLinkAboutFish Creek Hydrology Evaluation 2016Hyddrolo Rep Aug ogy port gust 2014 y t 4 1601 Blake Street, Suite 200 Denver, Colorado 80202 (303) 572-0200 fax (303) 572-0202 August 21, 2014 Mr. Kyle Arend, PE Larimer County Engineer 200 W. Oak St., Suite 3000 Fort Collins, Colorado 80521 RE: Fish Creek Hydrology Report Dear Mr. Arend: Matrix Design Group, Inc., under the direction and design lead of HDR, is pleased to submit the following Fish Creek Public Infrastructure Hydrology Report. This report is provided to reevaluate the design hydrology for Fish Creek after the devastating flood in September 2013. The prior regulatory 100-year flood flow for Fish Creek was set at 400 cfs; however, the recent extreme flood event may have peaked at approximately ten to twelve times that flow rate. This hydrology study establishes a basis for the design of public infrastructure as it relates to flood conveyance, channel stability and floodplain considerations. The attached report defines the hydrology along the Fish Creek corridor. The HEC-HMS hydrologic model for this 15.9 square mile watershed defines the 2-, 10-, 50-, and 100-year hydrology along the main stem of the drainageway, as well as certain design points within the watershed. This hydrologic information provides the project sponsors of Larimer County and the Town of Estes Park with updated modeling for better management of the watershed. We appreciate the opportunity to provide this report of our hydrologic analysis findings. Sincerely, Matrix Design Group, Inc. Robert Krehbiel, PE Scott Schreiber, PE Project Manager Water Resources Engineer Fish Creek Watershed Hydrology Evaluation Public Infrastructure Project August 2014 Page 1 Contents 1. Executive Summary ............................................................................................................ 2 2. Introduction to the Public Infrastructure Project ................................................................... 5 3. Project Area Description ..................................................................................................... 7 4. Fish Creek Hydrology.......................................................................................................... 7 4.1. Purpose ............................................................................................................. 8 4.2. Mapping and Software ....................................................................................... 8 4.3. Data Collection .................................................................................................. 8 4.4. Flood History ..................................................................................................... 9 4.5. Previous Studies ............................................................................................... 9 4.5.1. FEMA: Flood Insurance Study ..........................................................................10 4.5.2. NRCS: Colorado Front Range Flood of 2013....................................................10 4.5.3. CDOT Hydrologic Evaluation of the Big Thomson Watershed ..........................11 4.6. Public Infrastructure Hydrology Study ...............................................................14 4.6.1. September Flood High Water Mark Evaluation .................................................14 4.6.2. USGS Stream Stats Application .......................................................................15 4.6.3. Colorado Water Conservation Board ................................................................16 4.6.4. Flood Frequency Analysis (Statistical Analysis of Gage Records) ....................16 4.6.5. Similar Watershed ............................................................................................19 4.6.6. HEC-HMS ........................................................................................................19 4.6.6.1. Model Runs ......................................................................................................21 4.6.6.2. Calibration of Model ..........................................................................................23 5. References ........................................................................................................................25 Appendix A: Floodplain Map .....................................................................................................26 Appendix B: High Water Mark Analysis .....................................................................................28 Appendix C: USGS StreamStats Output ...................................................................................30 Appendix D: NRCS Regional Skew Analysis .............................................................................32 Appendix E: HEC-SSP Output ..................................................................................................34 Appendix F: Sub Basin Map ......................................................................................................36 Appendix G: Sub Basin Characteristics Table ...........................................................................38 Appendix H: Design Point Map .................................................................................................40 Fish Creek Watershed Hydrology Evaluation Public Infrastructure Project August 2014 Page 2 1. Executive Summary The September 2013 extreme flood event was a realization that major floods can and do occur in Colorado. Fish Creek is normally a small mountain babbling brook through a mountain residential community. The 2013 flood on Fish Creek in Estes Park, Larimer County caused major damage and is considered to be well beyond a 100-year flood event based upon the rainfall data for the 15.9 square mile watershed. There are no gage records that accurately measured the magnitude of the 2013 event on Fish Creek; however, post- flood estimates based upon high water marks and hydrologic modeling suggest the 2013 event was 2,000 cfs to 4,800 cfs (cubic feet per second). There are complexities in defining a peak flow rate, considering surges caused by a dam breach on Scott Pond, debris dam blockages, and embankment failures of roadway crossings. In 1979, FEMA established a 100-year discharge of 400 cfs based upon 30 years of gage records. Until September 2013, this flow rate appeared to establish a reasonable level of risk on Fish Creek. This study provides a recommended updated of the 100-year discharge for the design of public infrastructure reconstruction. Different methodologies were used to analyze the Fish Creek hydrology, including a statistical analysis of 55 years of gage records, evaluation of high water marks, a HEC-HMS hydrologic model, and regional regression equations. Results for a 100-year discharge were wide spread and ranged from 278 cfs to 2,374 cfs. This study recommends establishing a 100-year discharge at the mouth of Fish Creek into Lake Estes at 990 cfs based upon a statistical analysis of the gage records which incorporated the peak flow rate from the 2013 event at 2,400 cfs as the natural rainfall- runoff hydrology without the influence of any type of dam failures. This flow rate is nearly 2½ times higher than the previously regulated 100-year discharge. This flow rate analysis is based upon a look backward at 55 years of records, and assumes weather in the future will be similar to the past, without defined climatic changes. A hydrologic model was developed for the Fish Creek watershed to establish different recurrence interval hydrology at various points along the watershed. The HEC-HMS model using a 3-hour storm hydrograph was calibrated to the statistical gage analysis by adjusting all basin parameter Curve Numbers equally. Design point locations and their discharges are shown in Table 1 based upon the calibrated HEC-HMS model. Table 1. Design Point Discharges Design Storm Recurrence Interval Design Point Location 2 Year 10 Year 50 Year 100 Year Upstream of Rockwood Lane 10 23 111 178 Upstream of Little Valley Road 14 58 266 426 Upstream of Scott Avenue 18 141 515 786 Upstream of Johnsen Lane 20 154 568 870 Downstream of Powelly Lane 22 177 637 970 At Lake Estes 23 181 651 990 • 1-3: Three HEC-HMS models were developed by Matrix and used the CWCB recommended lag time equation. The initial Curve Number (CN) values were modeled for a 24 hour, a 6 hour storm, and a 3 hour storm. • 4: HEC-HMS model but modified the lag time by using an actual Snyder lag time equation. The Snyder lag equation caused lag times to increase, therefore reducing the peak. • 5-6: Regression equations from USGS and CWCB. • 7: HEC-SSP analysis by Matrix that included a September peak of 2400 cfs that used a skew analysis from NRCS (11 gages). • 8. HEC-SSP analysis by NRCS that used a Sept flow of 4800 cfs, Froude =0.7. Has been updated from 1600 cfs to include more gage years. • 9: HEC-SSP analysis by Anderson that used the original CDOT Sept value of 1712 cfs but with a skew analysis by Ayres (24 gages). • 10: FEMA’s effective 100 year flow prior to the September 2013 event. • 11: HEC-HMS Hydrologic model of design storms for the CDOT Evaluation of Big Thompson Watershed. Fish Creek as one large basin 2,374 1,569 1,310 1,435 278 417 1,354 1,247 400 496 990 0 500 1,000 1,500 2,000 2,500 1. H E C -HM S ( I n i t i a l C N = 6 9 . 0 ) 2. H E C -HM S ( I n i t i a l C N , 6 H o u r St o r m ) 3. H E C -HM S ( I n i t i a l C N , 3 H o u r St o r m ) 4. H E C -HM S ( I n i t i a l C N a n d S n y d e r La g ) 5. U S G S : S t r e a m S t a t s 6. C W C B : R e g r e s s i o n E q u a t i o n 7. H E C -SS P ( S e p t Q = 2 4 0 0 c f s , N R C S Sk e w , 5 5 Y e a r D a t a ) 8. N R C S : H E C -SS P ( S e p t Q = 4 8 0 0 , NR C S S k e w , 4 8 Y R + 7 Y R ) 9. A n d e r s o n : H E C -SS P ( S e p t Q= 1 7 1 2 , A y r e s S k e w , 3 3 Y e a r D a t a ) 10 . F E M A : F l o o d I n s u r a n c e S t u d y Fr o m 1 9 7 9 11 . H E C -HM S C D O T : O n e L a r g e Ba s i n C N = 5 5 . 7 Fl o w [ c f s ] Fish Creek Watershed 100 Year Flow Comparisons • 1: HEC-RAS evaluation of high water marks to determine September 2013 flow, discounting surges caused by Scott Ponds dam breach. • 2-3: CDOT Hydrology Evaluation of Big Thompson Watershed. The first model was calibrated based upon the cumulative rainfall from all 10 days of the storm, while the second model evaluated only the greatest rainfall amount for 24 hours. • 4-5: Critical depth method evaluation by NRCS using Froude of 1.0 and 0.7. 2,400 1,994 1,712 6,900 4,800 0 1,000 2,000 3,000 4,000 5,000 6,000 7,000 8,000 1. H E C -RA S H i g h W a t e r M a r k Ev a l u a t i o n 2. C D O T : S e p t e m b e r E v e n t , Cu m u l a t i v e 1 0 D a y 3. C D O T : S e p t e m b e r E v e n t , M a x 24 H o u r P e r i o d 4. N R C S : S e p t E v e n t , F r o u d e = 1 . 0 5. N R C S : S e p t E v e n t , F r o u d e = 0 . 7 Fl o w [ c f s ] Fish Creek Watershed September 2013 Flow Comparisons Fish Creek Watershed Hydrology Evaluation Public Infrastructure Project August 2014 Page 5 2. Introduction to the Public Infrastructure Project Fish Creek flows northerly through Larimer County and the Town of Estes Park to its confluence with the Big Thompson River at Lake Estes (see attached Vicinity Map). The purpose of this study is to evaluate hydrologic conditions in the basin and develop design hydrology for a 100 year recurrence interval. September 2013 flooding caused extensive damage to roads, bridges, utilities, homes and businesses throughout much of Larimer County, including the Estes Valley. The Fish Creek floods damaged and destroyed significant portions of Fish Creek Road in both the Town of Estes Park and unincorporated Larimer County. The flood also damaged and destroyed significant portions of the sanitary sewer, municipal electric and water lines, bicycle/pedestrian trail, and stream channel in and adjacent to Fish Creek Road. Larimer County, Town of Estes Park, Upper Thompson Sanitation District and the Estes Valley Recreation & Park District have all signed an Intergovernmental Agreement to complete flood repair work along the Fish Creek Corridor from SH 7 at Mary’s Lake Road to Lake Estes/US 36. These Fish Creek Project Partners are working with funding agencies (Federal Emergency Management Agency, Colorado Department of Transportation and Federal Highway Administration) to plan, design and build the improvements needed to repair the utilities, trail, Fish Creek Road and cross-streets connection to Fish Creek Road. A substantial amount of work has already been completed on Fish Creek late in the fall of 2013 and early in 2014. The Fish Creek Project Partners have undertaken various emergency and temporary repairs to restore some level of service and functionality until permanent repairs can be designed and constructed. A temporary sanitary sewer line has been placed in the corridor with a minimal amount of cover. Some fill material has been placed in the roadway prism to provide a temporary two-lane roadway. Culverts and fill have been placed at some of the local road crossings over Fish Creek to restore access. The Fish Creek Project Partners are assessing the work needed to complete permanent repair work and determined sources of funding. Larimer County contracted with HDR for the design of public infrastructure permanent repairs to utilities (sanitary sewer, water, electric), Fish Creek Road, the trail and local street connections. ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! Fish CreekStudy Area Rocky MountainNational Park £¤36 §¨¦25 §¨¦25 §¨¦25 §¨¦76 §¨¦70 £¤36 £¤34 £¤287 £¤34 £¤287 £¤287 £¤36 £¤36 £¤36 UV119 UV46 UV7 UV72 UV279 UV72 UV119 UV72 UV119 Ward Lyons Denver Arvada Eldora Boulder Thornton Longmont Berthoud Loveland Broomfield Louisville Allenspark Estes Park Westminster FI L E : G : \ g i s _ p r o j e c t s \ F i s h _ C r e e k _ E s t e s _ P a r k \ a c t i v e \ a p p s \ F i s h _ C r e e k _ V i c i n i t y _ M a p . m x d , 5 / 2 3 / 2 0 1 4 , S c o t t _ S c h r e i b e r Vicinity Map o 0 52.5 Miles Fish Creek - Estes Park, CO Fish Creek Watershed Hydrology Evaluation Public Infrastructure Project August 2014 Page 7 3. Project Area Description Fish Creek is located in Larimer County with outlet into Lake Estes in the Town of Estes Park. The Fish Creek watershed is located in Township 4N Range 73W, Township 4N Range 72, Township 5N Range 73, and Township 5N Range 72, of the 6th PM. Fish Creek originates in the mountains south of Estes Park. Fish Creek flows north following Fish Creek Road and enters Lake Estes on the south side. The headwaters of Fish Creek are mostly mountainous undeveloped forest area with residential development increasing to the north towards Lake Estes and the Town of Estes Park. The channel of Fish Creek is well defined and generally narrow, with sand and cobble streambeds, and heavy vegetation along the channel banks. The waters of Fish Creek experience significant impacts from spring runoff of snowmelt. There are two lakes located at the upstream end of the basin, Lilly Lake and Mary’s Lake. Directly upstream of Scott Avenue are two additional recreational ponds called the Scott Ponds. None of these water storage impoundments provide flood control on Fish Creek. The total length of the damaged creek is approximately 4.5 miles with a drainage basin of 15.9 square miles. Fish Creek Road is intersected by several local roadways. Key road crossings occur at Brodie Avenue, Country Club Drive, Brook Drive, Scott Avenue, Whispering Pines Drive, Little Valley Road, Rockwood Circle and Rockwood Lane. In addition, there are approximately 13 private accesses off of Fish Creek Road. 4. Fish Creek Hydrology The stream channel of Fish Creek was drastically altered by the flood, altering the location of the channel thawleg, scouring the channel in some locations and depositing sediment in others, and eroding the banks of the channel. Defining stable channel geometry that mitigates future risk is important to the overall restoration design. There is significant interest among the project partners and in the broader community in restoring or modifying the Fish Creek channel to reduce the risk and impact of future flooding along the channel and to restore Fish Creek’s ecological health and resiliency. The Natural Resources Conservation Service (NRCS) has managed several exigent or urgent watershed protection measures along the Fish Creek channel. The Colorado Water Conservation Board has funded a master plan for Fish Creek through the Town of Estes Park. However, no funding for construction of significant stream channel restoration has been secured to-date. Construction of ecological restoration efforts may lag behind the road, trail and utility repair work, but the analysis of the stream corridor is occurring to inform the design of the public infrastructure repair work for the roadway, trails and utilities. Fish Creek Watershed Hydrology Evaluation Public Infrastructure Project August 2014 Page 8 Design stream channel hydrology and hydraulics is being considered for roadway culvert sizing, floodplain evaluations, utility infrastructure design and road alignments. 4.1. Purpose FEMA defined a single point 100-year flood flow for Fish Creek in 1979, 35 years ago. Since a flow of this magnitude or greater has been observed three times in the last 66 years, an updated evaluation of the hydrology is recommended. The hydrologic model developed for this study provides discharges for differing recurrence intervals and intermediate design flows along the waterway. An updated hydrologic analysis of Fish Creek provides better input into the hydraulic model for the design of infrastructure protection. This report provides design flows for the 2-, 10-, 50- and 100-year recurrence interval floods for analysis of the hydraulics on Fish Creek. 4.2. Mapping and Software The United States Army Corps of Engineers (USACE) Hydrologic Engineering Center’s Geospatial Hydrologic Modeling Extension, HEC-GeoHMS, was used in conjunction with ESRI’s ArcGIS Software and Spatial Analysis extension as the primary tool for delineating basin areas and characteristics. HEC-GeoHMS is a spatial analysis software platform used inside of ArcGIS to determine various physical watershed characteristics. Existing topography in the area, combined with soils groups and land cover, was used to delineate basin areas and determine runoff characteristics. The overall basin boundary for Fish Creek was generated from USGS topography. These watershed characteristics were then analyzed using another USACE software program called HEC-HMS which is a hydrology modeling system that can be used to develop anticipated design flows. Data acquired from HEC-GeoHMS can be outputted into basin files which then can be used to develop initial model parameters in HEC-HMS. HEC- HMS then can be used for computations of multiple hydrologic methods, while at the same time developing scenarios for model calibration. ESRI’s ArcGIS software was also used to evaluate high water marks on Fish Creek. The Corps Hydrologic Engineering Center’s River Analysis System, HEC-RAS, hydraulic model was used to evaluate those high water marks. 4.3. Data Collection To facilitate the hydrologic modeling of the Fish Creek watershed with HEC-GeoHMS software, various GIS datasets were acquired. Topographic data were derived from a USGS 10 meter Digital Elevation Model (DEM). Information related to soil type and hydrologic soil group was obtained from the NRCS Soil Survey Geographic Database (SSURGO). The Fish Creek watershed extent includes three soil surveys:  Estes Park Area, Colorado, Parts of Boulder and Larimer Counties (CO642), 12/6/2013  Arapaho-Roosevelt National Forest Area, Colorado, Parts of Boulder, Clear Creek, Gilpin, Grand, Park, and Larimer Counties (CO645), 12/23/2013 Fish Creek Watershed Hydrology Evaluation Public Infrastructure Project August 2014 Page 9  Rocky Mountain National Park, Colorado, Parts of Boulder, Grand, and Larimer Counties (CO651), 12/23/2013 The 2006 USGS National Land Cover Database (NLCD) was used to determine land use within the watershed. Curve Numbers (CN) required for the HEC-HMS model were developed by overlaying a GIS union of the soils and land cover datasets and then comparing the results to a lookup table based on the Soil Conservation Service’s TR-55 publication. All the datasets were compiled using ArcGIS in order to evaluate the watershed using tools of HEC-GeoHMS. High water mark information was provided in a survey by Icon Engineering. These high water marks were documented using a GPS and uploaded as shapefiles. 4.4. Flood History Gage records are available at the mouth of Fish Creek for 55 years, from 1947 to 1979, and 1990 to 2012, excluding 1992. According to the records, a notable flood occurred May 25, 1951 with a peak flow of 1,480 cfs, which was caused by a dam break on Lilly Lake. On July 29, 1956, the gage recorded a peak flow of 400 cfs. All other recorded annual peak flows have been less than 200 cfs. At least 13 floods have been documented on the Big Thompson, which is the receiving water of Fish Creek, including the devastating flood of 1976. However, the peak flow in Fish Creek in 1976 peaked at 194 cfs. It is important to note that during the September 2013 flood event, there was a breach of a dam that impacted the flow on Fish Creek. The most downstream pond experienced a dam breach during the September event. The volume or flow rate associated with this breach is currently unknown. 4.5. Previous Studies FEMA originally defined the 100-year hydrology for Fish Creek in 1979 as 400 cfs. The NRCS documented estimated flood discharges of the September 2013 flood using high water marks. A report titled, “Colorado Front Range Flood of 2013: Peak Flow Estimates at Selected Mountain Stream Locations” by the USDA Natural Resources Conservation Service, dated December 2013 computed the peak flow at 6,900 cfs based upon high water marks and channel cross sections. Comments were received from the NRCS that reduced their estimate of the September event to 4,800 cfs based upon a Froude number of 0.7. The “Draft Hydrologic Evaluation of the Big Thompson Watershed, Post September 2013 Flood Event,” dated April 2014 by Jacobs Engineering Group, Inc. hydrologically modeled the flood event to be 1,994 cfs based upon recorded rainfall data. Fish Creek Watershed Hydrology Evaluation Public Infrastructure Project August 2014 Page 10 4.5.1. FEMA: Flood Insurance Study The effective Larimer County Flood Insurance Study (FIS) was originally published in 1979 by the Federal Emergency Management Agency (FEMA) and was republished on February 6, 2013. FEMA effective regulatory hydrology is shown in Table 2. Table 2. FIS Design Discharges Fish Creek Drainage Area 10 year Flood 50 Year Flood 100 Year Flood 500 Year Flood At Lake Estes 16.0 sq mi 105 cfs 280 cfs 400 cfs 840 cfs At Estes Park Corporate Limits 13.4 sq mi 105 cfs 280 cfs 400 cfs 840 cfs At Upstream Detailed Study Limit 13.4 sq mi 105 cfs 280 cfs 400 cfs 840 cfs Fish Creek through the Town of Estes Park is a detailed floodplain study with elevations (Zone AE) and published as effective on October 1, 2012. A small portion of Fish Creek in Larimer County upstream of the Estes Park town boundary is defined by an approximate floodplain (Zone A). The upstream reminder of Fish Creek has does not have a regulatory defined floodplain. See Floodplain Map in Appendix A for further information. 4.5.2. NRCS: Colorado Front Range Flood of 2013 A study was recently performed by the NRCS in December 2013 to evaluate peak flow estimates at selected mountain locations that occurred during the September 2013 flood. Peak stream flows caused by the September flood were approximated using the critical depth method. The critical depth method uses cross sectional geometry and observed high waters marks to determine the peak stream flow. This was completed using a relationship between the Froude number equation and the continuity equation. Assuming the water surface is below critical depth due to stream bed slopes greater than 1%, a Froude number of 1.0 was is assumed. Three cross sections were evaluated for this study and the results were averaged. The cross sections were located at downstream end of Fish Creek near Brodie Avenue. The site selected, as can be seen in the image on the following page, has been disturbed since the flood for emergency sanitary repair work. See Appendix B for the location of the NRCS cross section on Fish Creek. This study estimated the Fish Creek drainage experienced greater than a 500 year storm, with 6,900 cfs in September 2013. The average slope of the channel in the study area was 0.015 ft/ft with a width of about 11 feet causing approximately the water level to be 9.5 feet deep. Fish Creek Watershed Hydrology Evaluation Public Infrastructure Project August 2014 Page 11 The NRCS later modified of the Froude number to 0.7 to better represent backwater effects from Lake Estes. This also correlates better with an average channel slope of 1.5% causing a velocity of 7.9 feet per second. The NRCS stated in their comments this modification reduces their estimation of the September 2013 event to 4,800 cfs. 4.5.3. CDOT Hydrologic Evaluation of the Big Thomson Watershed An ongoing study for the Big Thompson watershed is being performed by Colorado Department of Transportation (CDOT) to ascertain the approximate magnitude of the September 2013 flood event and to prepare estimates of peak discharges associated with various return periods. The report is currently in draft form awaiting comments. The Big Thompson River is the receiving body of Fish Creek. Fish Creek is considered part of the Big Thompson Watershed, therefore hydrology calculations were performed on the Fish Creek sub basin. Due to the nature of this study dealing mainly with the hydrology and hydraulics of the Big Thompson River, the Fish Creek watershed was delineated as one single basin for the Big Thompson hydrologic evaluation. The Curve Number used in their model of the Fish Creek watershed was 55.7. This study was performed using the HEC-GeoHMS and HEC-HMS software platforms. Spatial data was acquired from USGS and used to delineate and characterize watersheds. Runoff parameters and lag times were computed and applied to the Snyder Unit Hydrograph to determine peak flow measurements. Once the watersheds physical characteristics were initially modeled, they were calibrated based upon observed flows from either high water marks or lake hydrographs. All of the basins upstream of Lake Estes, 154 square mile drainage area, including Fish Creek, were calibrated based upon the Lake Estes inflow hydrograph. Fish Creek experienced some of the highest rainfall totals and intensities in the study area. Table 3 from the Draft CDOT report outlines the various rainfall depths from the September event and associated NOAA recurrence interval. The total 24 hour rainfall depth experienced during the September event is greater than a 1000 year storm; however, the peak rainfall intensity resembled a much less significant rainfall event, on the order of a 10 to 25 year storm. The graphic on the following page produced by NOAA displays the annual exceedance probabilities for the worst case 7-day rainfall, and shows the rainfall in the area around Estes Park to exceed a 1000 year event. Fish Creek Watershed Hydrology Evaluation Public Infrastructure Project August 2014 Page 12 Table 3. September 2013 Event Rainfall Depths Duration Rainfall (inches) NOAA Recurrence Interval (years) 10-day 12.36 >1000 24-hour 8.02 >1000 6-hour 3.77 100 to 200 1-hour 1.11 10 to 25 Table 4 outlines the estimated September event and various design storms for Fish Creek watershed developed for the CDOT study. The estimated September event flow was based upon the maximum rainfall that occurred over the ten day event. This value was then used to calibrate the hydrological model to develop a typical 24 hour NOAA storm. An area rainfall reduction was not performed on Fish Creek in this study due to the relative magnitude of the event that happened. Table 4. CDOT Design Discharges Fish Creek Drainage Area September Event 10 year Flood 50 Year Flood 100 Year Flood 500 Year Flood At Lake Estes 16.7 sq. mi 1,994 cfs 48 cfs 281 cfs 496 cfs 1,352 cfs All basins upstream of Lake Estes were calibrated together based on one hydrograph. The entire Fish Creek watershed was modeled as one basin. This study further subdivided the Fish Creek watershed into smaller sub-watersheds. It is very common for hydrologic models that discretizing a large basin into a number of smaller basins to result in an increase in the overall peak due to routing elements reducing the lag time between rainfall and runoff. The lag time from the CDOT model for the Fish Creek watershed was 3.96 hours. There is a discrepancy in the drainage area from the CDOT study and this study, 16.7 square miles compared to 15.9 square miles, respectively. Fish Creek Watershed Hydrology Evaluation Public Infrastructure Project August 2014 Page 13 Figure 1. NOAA Worst Case 7-Day Rainfall Fish Creek Watershed Hydrology Evaluation Public Infrastructure Project August 2014 Page 14 4.6. Public Infrastructure Hydrology Study The evaluation of hydrology in the Fish Creek watershed was performed using four different methods. The first method evaluated high water marks from the September event with a HEC-RAS model to determine the flow from that event. Two methods used regional regression equations for estimation of various stream flow statistics that are representative of natural stream flow conditions at ungauged sites in Colorado. The fourth method performed was a hydrologic model analysis using HEC-HMS hydrologic model software. 4.6.1. September Flood High Water Mark Evaluation The flood event in September 2013 caused substantial damage to the Fish Creek watershed. Along with the damage assessed, high water marks were also observed and documented to provide peak flow estimates. These high water marks were surveyed and mapped by Icon Engineering. High water marks evaluated included bent grass and slack water deposits of fine sediment organic material, and ash along the channel margins. The NRCS performed peak flow estimates on Fish Creek by evaluating high water marks at three cross sections using the critical depth method. A number of other high water marks were surveyed throughout Fish Creek watershed and evaluated. These additional high water marks were evaluated further by developing a HEC-RAS model that could be calibrated to the high water marks by adjusting and evaluating the flow regime. The post- flood HEC-RAS model was provided by the CWCB. The HEC-RAS model assumed a manning’s of 0.04 in the channel and 0.05 in the floodplains. Thirty eight observed water surface elevations were develop and applied to the HEC-RAS model. The elevations were examined in HEC-RAS by plotting their location spatially along the creek profile. A number of various flow rates were modeled to determine which flow rate best matched the observed high water marks. Appendix B includes a graphic showing the profile of Fish Creek with associated high water marks and an aerial displaying HEC-RAS cross sections and the high water marks. Shown on the provided profiles is the location of Scott Ponds in relationship to the HEC- RAS model. The first cross section downstream of Scott Ponds is cross section 12409.49. The drainage area upstream of Scott Ponds is 13.2 square miles, while downstream of Scott Ponds is 2.6 square miles, 83% and 17% of the overall watershed, respectively. The high water marks downstream of Scott Ponds may have been influenced by the breach on the lower of the two Scott Ponds. As shown on the profile, the estimate of flows downstream of Scott Ponds range from 2,000 to 4,800 cfs, while the flows upstream of Scott Ponds range from 800 to 2,000 cfs. If the flows upstream of Scott Ponds are to represent 83% of the drainage area, then the flows downstream of Scott Ponds should be approximately 2,400 cfs, assuming a direct correlation to basin area. Therefore the flow rate, for the September event, based upon actual measured high water marks is estimated to be 2,400 cfs for a natural rainfall-runoff without the influence of dam breaks. This peak 2013 flow rate of 2,400 cfs was used as an additional data point to supplement the HEC-SSP statistical analysis of annual peak flows. Fish Creek Watershed Hydrology Evaluation Public Infrastructure Project August 2014 Page 15 4.6.2. USGS Stream Stats Application USGS StreamStats is a Web-based Geographic Information System (GIS) that provides users with access to an assortment of analytical tools that are useful for water-resources planning and management, and for engineering design applications, such as the design of bridges and stream crossings. StreamStats allows users to easily obtain stream flow statistics, drainage-basin characteristics, and other information for user- selected sites on streams. Included with those statistics are design storms based upon standard recurrence intervals. The StreamStats application was developed by USGS in conjunction with CWCB (2009). The State of Colorado was divided into 5 regions based upon similar basin characteristics. The Fish Creek watershed is considered to lie in the Mountain Region. Below are the associated peak stream flow equations for various return intervals along with the applicable ranges. Table 5. StreamStats Regression Equations The variables the design flows are based upon are ‘A’, area in square miles, and ‘S’, average basin slope. Variables were determined inside web based program and then reported in PDF format along with flow characteristics. The entirety of this model output report is available in Appendix C. The Fish Creek watershed was modeled as having a drainage area of 15.9 square miles, a mean basin slope of 29.6% and a mean annual precipitation of 21.43 inches. The drainage area and the mean annual precipitation both fall within the suggested range, but with a mean basin elevation of 8590’, it is below the minimum mean basin elevation of 8600’, and therefore include extrapolations with unknown errors. The prediction error associated with the 100 year recurrence interval is 36%. Table 6 outlines the results of the StreamStats program for various recurrence intervals and their design flows. Fish Creek Watershed Hydrology Evaluation Public Infrastructure Project August 2014 Page 16 Table 6. StreamStats Design Discharges Design Storm Flow [Qyear] [cfs] Q2 86 Q5 130 Q10 161 Q25 199 Q50 243 Q100 278 4.6.3. Colorado Water Conservation Board The Colorado Water Conservation Board (CWCB) Floodplain and Stormwater Criteria Manual provides additional regional regression equations which can be used as a simplified procedure of estimating peak flow rates for various frequency storm events for unregulated streams with short or no stream flow records. The CWCB developed these set of equations to further refine the USGS equations into smaller, more replicative basins. The State of Colorado was divided into seven major hydrologic regions, of which the Fish Creek watershed is a part of the Mountain Region. The CWCB did not develop regression equations for any design storm recurrence interval except for the 100 year. Below is the 100 year recurrence interval regression equation for the Mountain Region: Q100 = 39.5(A).706 (S+1.0)1.577 The variables the design flow is based upon are ‘A’, area in square miles, and ‘S’, average basin slope. The equation is considered valid with an area between 5.5 square miles and 945 square miles, and a slope between 0.126 ft/ft and 0.554 ft/ft. With the Fish Creek watershed having a basin area of 15.9 square miles and an average basin slope of 0.288 ft/ft, the approximate 100 year flow is 417 cfs. The standard error of estimate is 42%. 4.6.4. Flood Frequency Analysis (Statistical Analysis of Gage Records) The hydrology for Fish Creek was also determined using a statistical analysis software package developed by the US Army Corps of Engineers called HEC-SSP. This software package allows for a statistical analysis of historical stream gage data with guidance from Bulletin 17B using Log Person Type III Distribution to develop hydrology data for design storm recurrence intervals. A weighted skew was used as directed by the CWCB guidance. At the most downstream point in Fish Creek watershed, prior to entering Lake Estes, there is a stream gage. This is gage ‘06734500 Fish Creek near Estes Park’ monitored by Division of Water Resources. It was originally installed by USGS and then consequently handed over to the US Bureau of Reclamation (USBR), and then to the Colorado Division of Water Resources. The Fish Creek gage has 55 years of record from 1947 to 2012 with gaps in data for 1980 through 1989 and 1992. Included with this data set was a data point Fish Creek Watershed Hydrology Evaluation Public Infrastructure Project August 2014 Page 17 from 1951 that was caused by a dam break. Due to this being a dam break on Lilly Lake, the data was not used in the HEC-SSP analysis. The data was also supplemented with September 2013 event flow of 2,400 cfs as documented from high water marks along with a HEC-RAS analysis, therefore totaling 55 years of data total. The graph and table on the following page outlines the values used in the HEC-SSP analysis. A Regional Skew analysis was performed and provided by Steve Yochum of the NRCS, (Yochum, 2014) and can be found in Appendix D. This analysis was completed on 11 gages near the Fish Creek Watershed that included September 2013 events. As documented in CWCB guidance the station skew and mean squared error is weighted with a regional skew and mean squared error. Table 7 outlines the skews and the mean squared error. Table 7. Skew Analysis Station Regional Skew 0.888 Skew 0.819 Mean Squared Error 0.164 Mean Squared Error 0.326 Appendix E contains outputs for analysis. The 100 year flow from the HEC-SSP analysis was determined to be 990 cfs. This 100 year flow was used to calibrate the HEC-HMS model to allow for determination of various design points and design storms.     Gage Record  Date  Annual Peak  Streamflow   Gage Record  Date  Annual Peak  Streamflow    Gage Record  Date  Annual Peak  Streamflow   Gage Record  Date  Annual Peak  Streamflow  6/22/1947 53  7/8/1961 48   6/2/1975 28  4/23/2000 13  4/27/1948 14  4/29/1962 10  7/31/1976 194  7/5/2001 18  6/6/1949 108  6/16/1963 17  7/24/1977 153  5/24/2002 2  6/9/1950 5  4/16/1964 3  5/19/1978 20  4/15/2003 18  6/3/1952 53  6/15/1965 56  6/17/1979 37  7/19/2004 45  5/18/1953 8  8/1/1966 7  4/25/1990 22  5/31/2005 18  10/23/1953 7  7/19/1967 17  6/2/1991 23  8/21/2006 16  7/23/1955 5  6/8/1968 9  5/17/1993 7  8/2/2007 31  7/29/1956 400  5/9/1969 117  8/13/1994 48  6/5/2008 11  5/9/1957 119  6/11/1970 19  5/30/1995 111  5/2/2009 13  5/14/1958 42  5/2/1971 42  5/26/1996 20  5/18/2010 35  6/21/1959 33  8/16/1972 21  6/8/1997 23  5/23/2011 22  5/5/1960 16  5/7/1973 77  5/13/1998 30  7/7/2012 107    6/9/1974 8  5/27/1999 46  9/13/2013 2,000                  *Gage record of 1480 cfs from 1951 caused by dam breach.    0 250 500 750 1000 1250 1500 1750 2000 2250 1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010 2015 An n u a l  Pe a k  St r e a m f l o w  [c f s ] Gage Record Date USGS and DWR Stream Gage Data 06734500 Fish Creek Near Estes Park, CO  Fish Creek Watershed Hydrology Evaluation Public Infrastructure Project August 2014 Page 19 4.6.5. Similar Watershed – Fall River An analysis was performed on Fall River for a comparison to a similar watershed near Fish Creek. Fall River is located to the northwest of Fish Creek and has a confluence with Big Thompson prior to entering Lake Estes on the west side. The Fall River gage has a drainage area or 39.8 square miles and an elevation of 7,550 feet. Both Fall River and Fish Creek drain to Lake Estes. FEMA previously established 100-year flows for Fall River and Fish Creek as 680 cfs and 400 cfs, translating to a unit runoff of 17 cfs/mi2 and 25 cfs/mi2, respectively. A HEC-SSP statistical analysis of the gage data was performed on for Fall River. The Fall River gage has 25 years of data from 1945 to 1994. There was one dam break that was removed from the data set, 1982 with a flow rate of 6,550 cfs. The HEC-SSP analysis used a flow rate of 3,800 cfs for inclusion as the September 2013 event as reported in “Peak Flow Estimates at Selected Mountain Stream Locations” by the NRCS. The same regional skew information was used for Fall River and Fish Creek. Table 8 summarizes the unit flow rate comparison of Fish Creek and Fall River. The estimated 100 year flow rate computed from the statistical HEC-SSP analysis of Fall River was 2,724 cfs. This correlates to a flow rate of 68 cfs per square mile. From the Fish Creek HEC-SSP analysis it was estimated that Fish Creek has a 100 year flow rate of 990 cfs with a drainage area of 15.9 square miles, which correlates reasonably well to a flow rate of 62 cfs per square mile. Table 8. Similar Watershed Comparison Similar Watershed Drainage Area FEMA 100 Year Flow Rate FEMA 100 Year Unit Flow Rate Estimated Updated 100 Year Flow Updated 100 Year Unit Flow Rate [sq mi] [cfs] [cfs/ mi2] [cfs] [cfs/ mi2] Fall River 39.8 680 17 2,724 68 Fish Creek 15.9 400 25 990 62 4.6.6. HEC-HMS A hydrograph routing program, HEC-HMS, was used to calculate design storm recurrence interval runoff amounts. HEC-HMS is used by pre-processing spatial GIS information in HEC-GeoHMS using the ESRI ArcGIS platform. Data was collected for the study area and used to perform basin delineations and characterizations. Basin parameters were estimated using ESRI ArcGIS platform to determine basin characteristics by overlaying land uses with soils groups and basin delineations to determine average basin characteristics. Basin maps outlining some of these parameters are located in Appendix F. These parameters were used to model each sub-basin of the Fish Creek watershed in HEC-HMS. HEC-HMS allows for various modeling methods within the program. The Curve Number method was selected to determine infiltration losses since it is widely accepted in the engineering field and easy to calculate. As noted in Steve Yochum’s comments on a draft Fish Creek Watershed Hydrology Evaluation Public Infrastructure Project August 2014 Page 20 version of this report, a rainfall-runoff model is validated for Fish Creek due to the fact it is a mid-elevation watershed that has peak flows dominated by rainfall-runoff as opposed to snowmelt-runoff. The Snyder Unit Hydrograph was selected as the transform method since it was developed for watersheds similar to Fish Creek. For channel routing, the Muskingum- Cunge method with a typical 8-point cross section was selected. The Fish Creek watershed consists mainly of grassed and forested lands with some developed areas adjacent to the channel. The watershed was defined using USGS topographic mapping. The basin was subdivided into 19 sub-basins of equal dimensions of size and shape. Sub basin reaches were defined based upon a minimum tributary area of 0.4 square miles. The sub-basins were characterized based upon drainage area, weighted Curve Number, longest flow path, longest flow path from basin centroid, and basin slope. A table outlining initial basin parameters in available in Appendix G. The Curve Numbers for each sub basin were calculated based upon soils groups and land use. Other initial parameters were developed using HEC-GeoHMS inside ESRI ArcGIS. The area weighted average Curve Number computed for the entire Fish Creek watershed is 69.0. The Snyder Unit Hydrograph procedure to determine peak runoff rates from a basin includes the use of a peaking coefficient. A peaking coefficient of 0.4 was selected for all basins as being representative of mountainous areas. The main factor affecting the hydrograph peak and duration is the lag time. The lag time was calculated using guidance from CWCB Floodplain and Stormwater Criteria Manual. A default Kn of 0.15 for evergreen forests was used for basin roughness factor. The remaining input parameters include basin length, length to basin centroid, and average basin slope. These parameters were acquired using HEC-GeoHMS. (Alternate Lag Times were evaluated using the Snyder Lag time calculation and modifying the coefficient from 1.8 to 2.2. By increasing the coefficient the lag time increases. Lag times in general were longer for the Snyder method when compared to the CWCB method. Longer lag times result in reduced peak discharges.) The Muskingum-Cunge routing method was used to route runoff hydrographs generated from each basin. A typical channel cross-section was developed for the routing using an 8- point cross section that was triangular in shape with 3:1 side slopes reaching an 8 foot depth then transition to 4:1 side slopes in the floodplains. The Manning’s n values were set to a default of 0.04 for the channels and 0.05 for the overbanks areas. Channel slope and length parameters were obtained from HEC-GeoHMS. The NOAA Atlas 2 Precipitation-Frequency Atlas of the Western United States, Volume III- Colorado was used as the basis for determining rainfall amount associated with the various recurrence intervals. The estimated 100-year, 24-hour rainfall depth for the Fish Creek watershed is 4.38 inches. This rainfall depth can be compared to the max 24 hour rainfall that occurred during the September 2013 event of 8.02 inches, which was considered greater than a 1000 year event. Fish Creek Watershed Hydrology Evaluation Public Infrastructure Project August 2014 Page 21 Due to the fact the entire Fish Creek watershed is between 10 and 20 square miles, a depth area reduction factor (DARF) of 2% was applied to the rainfall depth, causing the 100 year applicable rainfall depth to become 4.29 inches. An SCS Type II storm distribution was used to develop a hyetograph. Hyetographs of differing storm durations, 2-hour, 3-hour, 6-hour and 24-hour were developed for Fish Creek. The recurrence interval storm depths and durations are provided in Table 9. Table 9. NOAA Design Rainfall Depths Recurrence Interval Calculated From NOAA Atlas 2 DARF 5 Mins 10 Mins 15 Mins 30 Mins 1-Hr 2-Hr 3-Hr 6-Hr 24-Hr 24-Hr (years) [in] [in] [in] [in] [in] [in] [in] [in] [in] [in] 2 0.23 0.36 0.45 0.63 0.80 0.94 1.04 1.21 1.79 1.75 10 0.40 0.63 0.79 1.10 1.39 1.60 1.75 2.00 2.80 2.74 50 0.57 0.89 1.12 1.56 1.97 2.22 2.41 2.70 3.80 3.72 100 0.65 1.01 1.27 1.77 2.23 2.53 2.76 3.11 4.38 4.29 4.6.6.1. Model Runs Initially, the model was developed using extracted parameters from spatial information without modifications. Therefore all Curve Numbers were derived directly from ArcGIS for associated soils group and land use codes. Table 10 outlines various land uses with soils groups and recommended Curve Number. The average area weighted Curve Number for the Fish Creek watershed was 69.0. (Compared to CDOT Hydrology Evaluation of the Big Thompson Watershed with a CN of 55.7) Fish Creek Watershed Hydrology Evaluation Public Infrastructure Project August 2014 Page 22 Table 10. Land Use / Curve Number Table Hydr. Soils Group Land Use A B C D Open Water 100 100 100 100 Developed - Open Space 39 61 74 80 Developed - Low Intensity 61 75 83 87 Developed - Medium Intensity 77 85 90 92 Barren Land (Rock/Sand/Clay) 77 86 91 94 Deciduous Forest 30 55 70 77 Evergreen Forest 30 55 70 77 Mixed Forest 30 55 70 77 Shrub/Scrub 30 48 65 73 Grassland/Herbaceous 39 61 74 80 Pasture/Hay 30 58 71 78 Woody Wetlands 78 78 78 78 Emergent Herbaceous Wetlands 78 78 78 78 Evaluation of the model at difference storm durations was also completed. The different storm durations were modeled in HEC-HMS using the built in frequency storm meteorological models for 2-hour, 3-hour, 6-hour and 24-hour storm durations and applicable storm hyetographs. It was found that the 24-hour storm duration created the greatest peak discharge. It was determined that the 3-hour storm duration best represents the Fish Creek watershed. Results of the model are as follows: HEC-HMS Model Results 100-Year Storm Storm Duration Computed 100 Year Flow (cfs) 2-Hour 1,087 3-Hour 1,310 6-Hour 1,569 24-Hour 2,374 The design storm duration should be based upon the watershed size. Shorter storm durations are rainfall intensity driven. Larger watersheds use longer design storm duration driven by overall rainfall amounts (not intensity). CDOT’s Big Thompson watershed model used a 24-hour storm duration. The recommended storm durations by the Urban Drainage and Flood Control District are 2-hour for watersheds up to 10 square miles, and 3-hour for watersheds from 10 to 20 square miles. These are the minimum duration for each corresponding watershed size. The storm duration should not be less than the time of concentration of the watershed, therefore, the use of a 2-hour storm is not recommended for the Fish Creek watershed where the time of concentration is closer to 3 hours. Applying 3-hour storm instead of 24-hour storm meets the requirement of the time of concentration, and also represents typical frontal convective storms. Fish Creek Watershed Hydrology Evaluation Public Infrastructure Project August 2014 Page 23 The September 2013 was an upslope storm that resulted in a long lasting rainfall, but this condition is rare for the mountainous region. The 24-hour storm duration is a better simulation the September event, but may not suit well for 100-year event simulation. 4.6.6.2. Calibration of Model Once the initial run was performed using the parameters outlined above, investigations were initiated to calibrate the model to known flows and previously performed studies. The calibration was performed using a 3-hour storm duration. The HEC-HMS model for the 100-year storm was calibrated to the computed 100-year discharge value from the statistical HEC-SSP Flood Frequency Analysis of 55 years of gage records. This flow rate analysis is based upon a look backward at 55 years of records, and assumes weather in the future will be similar to the past, without defined climatic changes. The HEC-HMS model was calibrated by adjusting the Curve Number. Calibration of the Curve Number to a known flow at an outlet can increase accuracy of a model due to the fact soils and land uses might not be developed correctly in steep mountainous regions. Curve Numbers also have the greatest effect on a rainfall-runoff model. All sub basin Curve Numbers were reduced equally downward by 6.75% in order to calibrate modeled flows with the estimated 100-year discharge value at the mouth of Fish Creek. Intermediate design points were established using the model along the waterway throughout the drainage basin to evaluate infrastructure needs. Table 11 lists the recommended design recurrence interval flows and their associated design point. Table 11. Fish Creek Design Discharges Design Storm Recurrence Interval Design Point Location 2 Year 10 Year 50 Year 100 Year Upstream of Rockwood Lane 10 23 111 178 Upstream of Little Valley Road 14 58 266 426 Upstream of Scott Avenue 18 141 515 786 Upstream of Johnsen Lane 20 154 568 870 Downstream of Powelly Lane 22 177 637 970 At Lake Estes 23 181 651 990 Appendix H contains a watershed map outlining the various design points within Fish Creek watershed. Figure 2 is the outflow hydrographic from the Fish Creek watershed. Fish Creek Watershed Hydrology Evaluation Public Infrastructure Project August 2014 Page 24 Figure 2. Fish Creek Outflow Hydrograph Fish Creek Watershed Hydrology Evaluation Public Infrastructure Project August 2014 Page 25 5. References 1. ArcMap; ArcGIS 10.1 SP1 for Desktop (Build 3143), ESRI; 1999-2012. 2. Colorado Floodplain and Stormwater Criteria Manual, Chapter 9 Hydrologic Analysis; Colorado Water Conservation Board; January 6, 2006. 3. Drainage Design Manual; Colorado Department of Transportation; 2004. 4. HEC-GeoHMS Geospatial Hydrologic Modeling Extension; Version10.1, U.S. Army Corps of Engineers; February 2013. 5. HEC-HMS Hydrologic Modeling System; Version 3.5, U.S. Army Corps of Engineers; August 2010. 6. Larimer County, Colorado Flood Insurance Study (FIS) #08069C; Federal Emergency Management Agency; Effective February 6, 2013. 7. National Engineering Handbook Part 630; Chapter 10, Estimation of Direct Runoff from Storm Rainfall; Natural Resources Conservation Service; July 2004. 8. National Oceanic and Atmospheric Administration (NOAA) Atlas 2, Precipitation Frequency Estimates; 1973. 9. Urban Hydrology for Small Watersheds – TR55; Natural Resources Conservation Service; June 1986. 10. Urban Storm Drainage Criteria Manual; Vol. 1, 2& 3, Urban Drainage and Flood Control District (UDFCD), Denver, Colorado, August 2006 (with revisions). 11. Water-Resources Investigations Report 85-4004, Determination of Roughness Coefficients for Streams in Colorado: By Robert D. Jarrett, U.S. Geologic Survey; 1985. 12. Water Supply Paper 1849, Roughness Characteristics of Natural Channels: By Harry H. Barnes Jr., U.S. Geologic Survey; 1967. 13. Colorado Front Range Flood of 2013: Peak Flow Estimates at Selected Mountain Stream Locations, USDA Natural Recourse Conservation Service Colorado, December 2013 14. Draft Hydrologic Evaluation of the Big Thompson Watershed Post September 2013 Flood Event, Jacobs, April 2014. 15. Comments on Draft Fish Creek Watershed Hydrology Evaluation Public Infrastructure Project, Steve Yochum, NRCS, 2014 Fish Creek Watershed Hydrology Evaluation Public Infrastructure Project August 2014 Page 26 Appendix A: Floodplain Map Service Layer Credits: Source: Esri, DigitalGlobe, GeoEye, i-cubed, USDA, USGS, AEX, Getmapping, Aerogrid, IGN, IGP, swisstopo, and the GIS UserCommunity Fish Cre ek Fis h C r e e k R d Johnsen L n Brodie Ave Manfo r d A v e Powelly Ln W in d h a m Ct Ce darLn Graves Ave M atthew Cir Wapiti Cir C o m m u n i t y D r Golf Club Rd B ra e sideLn Fa i r w a y C l u b C i r S k etch B o x L n Bir d i e L n FI L E : G : \ g i s _ p r o j e c t s \ F i s h _ C r e e k _ E s t e s _ P a r k \ a c t i v e \ a p p s \ F i s h _ C r e e k _ F l o o d p l a i n _ M a p _ D F I R M _ S h e e t _ 1 . m x d , 6 / 2 5 / 2 0 1 4 , w i l s o n _ w h e e l e r Floodplain MapSheet 1 of 2o 0 400200 Feet Fish CreekEstes Park, CO FEMA Floodplain (FIS) 100-Year Zone A 100-Year Zone AE 500-Year 007A 034A 036B034C 03 6 A Index Map Service Layer Credits: Source: Esri, DigitalGlobe, GeoEye, i-cubed, USDA, USGS, AEX, Getmapping, Aerogrid, IGN, IGP, swisstopo, and the GIS UserCommunity FishCre e k Fish C r e e k R d BrookDr Scott Ave Lon g v i e w D r S Sa i n t V r a i n A v e FlowerLn Av a l o n D r L a k eshoreDr Wi l low L n Country Club Dr Acacia Dr W i n d h a m Dr U plandsCir Ce d a r L n B r a dle y Ln W i n d h a m C t Peakview Dr Tra n q u il L n PineMeadow Dr GovernorsLn Baldp ate Ct NSharon Ct F a i r w a y L n V a i l C t Av a l o n D r A c a ciaDr FI L E : G : \ g i s _ p r o j e c t s \ F i s h _ C r e e k _ E s t e s _ P a r k \ a c t i v e \ a p p s \ F i s h _ C r e e k _ F l o o d p l a i n _ M a p _ D F I R M _ S h e e t _ 2 . m x d , 6 / 2 5 / 2 0 1 4 , w i l s o n _ w h e e l e r Floodplain MapSheet 2 of 2o 0 400200 Feet Fish CreekEstes Park, CO FEMA Floodplain (FIS) 100-Year Zone A 100-Year Zone AE 500-Year 007A 034A 036B034C 03 6 A Index Map Fish Creek Watershed Hydrology Evaluation Public Infrastructure Project August 2014 Page 28 Appendix B: High Water Mark Analysis NRCS Cross Section Locations 0 7536 7544.4 7519.8 7503.2 7562.3 7546.72 7538.527538.54 7545.61 7545.257545.57 7546.48 7546.55 7542.14 7518.97 7518.14 7515.147512.41 7511.08 7508.667507.63 7505.73 7502.247501.11 7497.16 7493.24 7491.787494.14 7500.92 7505.87 7511.34 7514.33 7526.54 7530.317531.24 7534.24 7545.27 7552.64 7556.91 7563.517566.38 7566.02 7570.347571.09 7571.67 7576.23 7567.63 7554.94 7547.85 7547.98 7545.19 7508.997510.36 7494.04 7492.87 7528.08 7490.79 4200 4000 4800 5000 5200 5400 5600 7600 5800 7400 6000 7200 6200 6600 6800 8809. 4 9 8609.4 9 9009 . 4 9 9209. 4 9 8009.07 9 8 9409.49 7778. 5 9 6 7919. 8 7 5 2 4489.1127 4582.8506 Source: Esri, DigitalGlobe, GeoEye, i-cubed, USDA, USGS, AEX, Getmapping, Aerogrid, IGN, IGP,swisstopo, and the GIS User Community, Esri, HERE, DeLorme, TomTom, MapmyIndia, © OpenStreetMapcontributors, and the GIS user community FI L E : G : \ g i s _ p r o j e c t s \ F i s h _ C r e e k _ E s t e s _ P a r k \ a c t i v e \ a p p s \ h y d r o l o g y \ F i s h _ C r e e k _ H i g h W a t e r M a r k s . m x d , 6 / 2 4 / 2 0 1 4 , S c o t t _ S c h r e i b e r High Water Mark Evaluation o0 100 200 300Feet Fish Creek - Estes Park, CO Sources: Esri, HERE, DeLorme,USGS, Intermap, increment PCorp., NRCAN, Esri Japan,METI, Esri China (Hong Kong),Esri (Thailand), TomTom,MapmyIndia, © OpenStreetMap High Water Mark Evaluation Inset Map SCOTT PONDS 0 7585 7589.9 7631.7 7649.5 7610.3 7562.3 7552.64 7556.91 7563.517566.38 7566.02 7570.347571.09 7571.67 7576.23 7581.517582.37 7585.31 7587.05 7593.587592.08 7608.737608.93 7620.24 7628.55 7628.84 7635.527635.43 7632.43 7629.09 7651.177652.08 7638.88 7641.05 7640.64 7626.38 7625.74 7621.857621.52 7619.82 7621.63 7610.197608.34 7601.91 7601.16 7591.91 7590.42 7587.72 7583.85 7567.63 7554.94 7628.46 7640.62 7635.55 9009 . 4 9 8809. 4 9 9209. 4 9 9609.49 9409.49 10009.49 10209.49 10409.49 114 0 9 . 4 9 10609.49 116 0 9 . 4 9 1120 9 . 4 9 11009 . 4 9 13809.49 1180 9 . 4 9 13609.49 1200 9 . 4 9 13409 . 4 9 12209. 4 9 132 0 9 . 4 9 130 0 9 . 4 9 12409.4 9 1280 9 . 4 9 10848.4419 9802.1 4 5 2 10783.7 2 9 6 Source: Esri, DigitalGlobe, GeoEye, i-cubed, USDA, USGS, AEX, Getmapping, Aerogrid, IGN, IGP,swisstopo, and the GIS User Community, Esri, HERE, DeLorme, TomTom, MapmyIndia, © OpenStreetMapcontributors, and the GIS user community FI L E : G : \ g i s _ p r o j e c t s \ F i s h _ C r e e k _ E s t e s _ P a r k \ a c t i v e \ a p p s \ h y d r o l o g y \ F i s h _ C r e e k _ H i g h W a t e r M a r k s . m x d , 6 / 2 4 / 2 0 1 4 , S c o t t _ S c h r e i b e r High Water Mark Evaluation o0 100 200 300Feet Fish Creek - Estes Park, CO Sources: Esri, HERE, DeLorme,USGS, Intermap, increment PCorp., NRCAN, Esri Japan,METI, Esri China (Hong Kong),Esri (Thailand), TomTom,MapmyIndia, © OpenStreetMap High Water Mark Evaluation Inset Map 4000 6000 8000 10000 12000 140007450 7500 7550 7600 7650 Fish Creek Plan: Plan 01 6/23/2014 Main Channel Distance (ft) El e v a t i o n ( f t ) Legend WS 4800 cfs WS 4000 cfs WS 3000 cfs WS 2000 cfs WS 1500 cfs WS 1000 cfs WS 800 cfs WS 400 cfs Ground OWS 4800 cfs 42 0 0 44 0 0 44 8 9 . 1 1 3 45 8 2 . 8 5 1 48 0 0 50 0 0 N R C S S t u d y 52 0 0 54 0 0 56 0 0 58 0 0 60 0 0 62 0 0 64 0 0 66 0 0 68 0 0 70 0 0 72 0 0 74 0 0 76 0 0 77 7 8 . 5 9 6 79 1 9 . 8 7 5 80 0 9 . 0 8 82 0 9 . 4 9 84 0 9 . 4 9 86 0 9 . 4 9 88 0 9 . 4 9 90 0 9 . 4 9 92 0 9 . 4 9 94 0 9 . 4 9 96 0 9 . 4 9 97 2 6 . 4 3 9 10 0 0 9 . 4 9 10 2 0 9 . 4 9 10 4 0 9 . 4 9 10 6 0 9 . 4 9 10 7 8 3 . 7 3 11 0 0 9 . 4 9 11 2 0 9 . 4 9 11 4 0 9 . 4 9 11 6 0 9 . 4 9 11 8 0 9 . 4 9 12 0 0 9 . 4 9 12 2 0 9 . 4 9 12 4 0 9 . 4 9 D o w n s t r e a m o f S c o t t P o n d 12 6 0 9 . 4 9 12 8 0 9 . 4 9 13 0 0 9 . 4 9 13 2 0 9 . 4 9 13 4 0 9 . 4 9 13 6 0 9 . 4 9 13 8 0 9 . 4 9 14 0 0 9 . 4 9 030922 97 4000 5000 6000 7000 8000 7490 7500 7510 7520 7530 7540 7550 Fish Creek Plan: Plan 01 6/23/2014 Main Channel Distance (ft) El e v a t i o n ( f t ) Legend WS 4800 cfs WS 4000 cfs WS 3000 cfs WS 2000 cfs WS 1500 cfs WS 1000 cfs WS 800 cfs WS 400 cfs Ground OWS 4800 cfs 42 0 0 44 0 0 44 8 9 . 1 1 3 45 3 6 . 5 6 7 48 0 0 50 0 0 N R C S S t u d y 52 0 0 54 0 0 56 0 0 58 0 0 60 0 0 62 0 0 64 0 0 66 0 0 68 0 0 70 0 0 72 0 0 74 0 0 76 0 0 77 7 8 . 5 9 6 78 2 1 . 0 7 9 78 6 0 . 0 0 2 79 1 9 . 8 7 5 80 0 9 . 0 8 82 0 9 . 4 9 030922 97 8000 9000 10000 11000 12000 7540 7550 7560 7570 7580 7590 7600 Fish Creek Plan: Plan 01 6/23/2014 Main Channel Distance (ft) El e v a t i o n ( f t ) Legend WS 4800 cfs WS 4000 cfs WS 3000 cfs WS 2000 cfs WS 1500 cfs WS 1000 cfs WS 800 cfs WS 400 cfs Ground OWS 4800 cfs 80 0 9 . 0 8 82 0 9 . 4 9 84 0 9 . 4 9 86 0 9 . 4 9 88 0 9 . 4 9 90 0 9 . 4 9 92 0 9 . 4 9 94 0 9 . 4 9 96 0 9 . 4 9 97 2 6 . 4 3 9 97 7 0 . 5 3 4 10 0 0 9 . 4 9 10 2 0 9 . 4 9 10 4 0 9 . 4 9 10 6 0 9 . 4 9 10 7 8 3 . 7 3 10 8 2 4 . 3 2 11 0 0 9 . 4 9 11 2 0 9 . 4 9 11 4 0 9 . 4 9 11 6 0 9 . 4 9 11 8 0 9 . 4 9 030922 97 11000 12000 13000 14000 15000 7590 7600 7610 7620 7630 7640 7650 Fish Creek Plan: Plan 01 6/23/2014 Main Channel Distance (ft) El e v a t i o n ( f t ) Legend WS 4800 cfs WS 4000 cfs WS 3000 cfs WS 2000 cfs WS 1500 cfs WS 1000 cfs WS 800 cfs WS 400 cfs Ground OWS 4800 cfs 11 0 0 9 . 4 . . . 11 2 0 9 . 4 9 11 4 0 9 . 4 9 11 6 0 9 . 4 9 11 8 0 9 . 4 9 12 0 0 9 . 4 9 12 2 0 9 . 4 9 12 4 0 9 . 4 9 D o w n s t r e a m o f S c o t t P o n d 12 6 0 9 . 4 9 12 8 0 9 . 4 9 13 0 0 9 . 4 9 13 2 0 9 . 4 9 13 4 0 9 . 4 9 13 6 0 9 . 4 9 13 8 0 9 . 4 9 14 0 0 9 . 4 9 030922 97 Fish Creek Watershed Hydrology Evaluation Public Infrastructure Project August 2014 Page 30 Appendix C: USGS StreamStats Output StreamStats Print Page 3/13/2014 9:52:27 AM USGS StreamStats http://streamstatsags.cr.usgs.gov/co_ss/default.aspx?stabbr=co&dt=1394725071223 1 of 1 3/13/2014 9:52 AM Streamstats Ungaged Site Report Date: Thu Mar 13 2014 08:53:47 Mountain Daylight Time Site Location: Colorado NAD27 Latitude: 40.3703 (40 22 13) NAD27 Longitude: -105.4926 (-105 29 33) NAD83 Latitude: 40.3703 (40 22 13) NAD83 Longitude: -105.4931 (-105 29 35) Drainage Area: 15.9 mi2 Peak-Flows Basin Characteristics 100% Mountain Region Peak Flow (15.9 mi2) Parameter Value Regression Equation Valid Range Min Max Drainage Area (square miles) 15.9 1 1060 Mean Basin Slope from 10m DEM (percent) 29.6 7.6 60.2 Mean Annual Precipitation (inches) 21.43 18 47 Low-Flows Basin Characteristics 100% Mountain Region Min Flow (15.9 mi2) Parameter Value Regression Equation Valid Range Min Max Drainage Area (square miles) 15.9 1 1060 Mean Annual Precipitation (inches) 21.43 18 47 Mean Basin Elevation (feet) 8590 (below min value 8600) 8600 12000 Warning: Some parameters are outside the suggested range. Estimates will be extrapolations with unknown errors. Flow-Duration Basin Characteristics 100% Mountain Region Flow Duration (15.9 mi2) Parameter Value Regression Equation Valid Range Min Max Drainage Area (square miles) 15.9 1 1060 Mean Annual Precipitation (inches) 21.43 18 47 Maximum-Flows Basin Characteristics 100% Mountain Region Max Flow (15.9 mi2) Parameter Value Regression Equation Valid Range Min Max Drainage Area (square miles) 15.9 1 1060 Mean Annual Precipitation (inches) 21.43 18 47 Mean-Flows Basin Characteristics 100% Mountain Region Mean Flow (15.9 mi2) Parameter Value Regression Equation Valid Range Streamflow Statistics Report http://streamstatsags.cr.usgs.gov/gisimg/Reports/FlowStatsReport236227... 1 of 3 3/13/2014 8:53 AM Min Max Drainage Area (square miles) 15.9 1 1060 Mean Annual Precipitation (inches) 21.43 18 47 Peak-Flows Streamflow Statistics Statistic Flow (ft3/s)Prediction Error (percent) Equivalent years of record 90-Percent Prediction Interval Minimum Maximum PK2 85.6 49 PK5 130 44 PK10 161 41 PK25 199 40 PK50 243 39 PK100 278 36 PK200 309 36 PK500 369 33 Low-Flows Streamflow Statistics Statistic Flow (ft3/s)Prediction Error (percent) Equivalent years of record 90-Percent Prediction Interval Minimum Maximum M7D2Y 0.31 M7D10Y 0.1 M7D50Y 0.21 Flow-Duration Streamflow Statistics Statistic Flow (ft3/s)Prediction Error (percent) Equivalent years of record 90-Percent Prediction Interval Minimum Maximum D10 24.2 19 D25 7.06 29 D50 2.96 29 D75 1.69 39 D90 0.95 72 Maximum-Flows Streamflow Statistics Statistic Flow (ft3/s)Prediction Error (percent) Equivalent years of record 90-Percent Prediction Interval Minimum Maximum V7D2Y 58 46 V7D10Y 102 35 V7D50Y 148 31 Mean-Flows Streamflow Statistics Statistic Flow (ft3/s)Prediction Error (percent) Equivalent years of record 90-Percent Prediction Interval Minimum Maximum Q1 1.87 24 Q2 1.77 26 Streamflow Statistics Report http://streamstatsags.cr.usgs.gov/gisimg/Reports/FlowStatsReport236227... 2 of 3 3/13/2014 8:53 AM Q3 1.97 24 Q4 4 19 Q5 27.9 21 Q6 52.3 21 Q7 15 56 Q8 6.81 61 Q9 4.21 32 QA 10.6 11 Q10 3.24 19 Q11 2.55 21 Q12 2.11 21 Streamflow Statistics Report http://streamstatsags.cr.usgs.gov/gisimg/Reports/FlowStatsReport236227... 3 of 3 3/13/2014 8:53 AM Fish Creek Watershed Hydrology Evaluation Public Infrastructure Project August 2014 Page 32 Appendix D: NRCS Regional Skew Analysis Log-Pearson Frequency Analysis Spreadsheet, Version 2.4, 3/2013 Page 1 of 3 Project:CO Front Range Floods of 2013 Streamgage:FISH CREEK NEAR ESTES PARK, CO Date:6/20/2014 Performed By:S. Yochum Without Generalized Skew Recurrence Percent K-Value Ln(Q) Peak(4) Interval(2)Chance Discharge Upper Lower Average:3.3189 (years)(cfs) (cfs) (cfs) Standard Deviation:1.3405269 200 0.5 3.616 8.1666 3,520 10,100 1,640 Skew Coefficient(1):1.1479212 100 1 3.117 7.4970 1,800 4,530 91850 2 2.605 6.8105 907 2,010 505 Length of systematic record:48 25 4 2.076 6.1019 447 870 271 Number of historic peaks:0 10 10 1.341 5.1159 167 276 112 Length of Data Record:48 5 20 0.739 4.3093 74 110 53 Length of Historic Record:(5)----2 50 -0.187 3.0680 22 30 151.25 80 -0.846 2.1847 9 13 61.05 95 -1.262 1.6268 5 8 3 With Weighted Generalized Skew 200 0.5 3.495 8.0042 2,990 8,290 1,430100 1 3.027 7.3762 1,600 3,930 827 Generalized Skew Coefficient(3):0.819 50 2 2.545 6.7307 838 1,830 471 Variance of Generalized Skew(3):0.326 25 4 2.045 6.0598 428 828 261 A:-0.175624 10 10 1.340 5.1153 167 276 112 B:0.641540 5 20 0.757 4.3338 76 114 54 station skew:1.147921 2 50 -0.165 3.0975 22 31 16 MSE Station Skew:0.2439678 1.25 80 -0.852 2.1772 9 13 6 Weighted skew coefficient(1):1.0071307 1.05 95 -1.314 1.5570 5 7 3 (1) Station and generalized skews must be between -2.00 and +3.00 in this spreadsheet. (2) Considering the relatively short length of many gage records, less frequent peak estimates need to be used with caution. (3) Computed one of four ways (see "generalized skew coefficient" worksheet): Mean and variance (standard deviation2) of station skews coefficients in region; skew isolines drawn on a map or regions; skew prediction equations; read from Plate 1 of Bulletin 17B (reproduced in this spreadsheet), with Variance of Generalized Skew = 0.302. (4) Results are automatically rounded to three significant figures, the dominant number of significant figures in the K-Value table. (5) Historic frequency analysis assumes that intervening years reflect systematic record. Comments:(I) Generalized skew attained by computing mean and variance of skews of 11 Larimer and Boulder County streamgages impacted by the 2013 flood. 2013 peaks included in all gage analyses. Data Plot: Peak Timing: 95% Confidence Limits 0 1000 2000 3000 4000 5000 6000 1900 1920 1940 1960 1980 2000 2020 An n u a l P e a k D i s c h a r g e ( c f s ) Date 0 5 10 15 20 123456789101112 Nu m b e r o f P e a k Ev e n t s Month Natural Resources Conservation Service 6/20/2014 Log-Pearson Frequency Analysis Spreadsheet, Version 2.4, 3/2013 Page 2 of 3 Project:CO Front Range Floods of 2013 Streamgage:FISH CREEK NEAR ESTES PARK, CO Date:6/20/2014 Performed By:S. Yochum Input Data Station ID:06734500 Latitude, Longitude:---- Drainage Area (mi2):15.7 County:Larimer Number of low outliers eliminated:0 State:CO Date Discharge Date Discharge Date Discharge (cfs)(cfs)(cfs) 1 06/22/1947 53 nn 51 ---- ----nn 101 ---- ----nn 2 04/27/1948 14 nn 52 ---- ----nn 102 ---- ----nn 3 06/06/1949 108 nn 53 ---- ----nn 103 ---- ----nn 4 06/09/1950 5 nn 54 --------nn 104 --------nn 5 05/25/1951 ----nn 55 ---- ----nn 105 ---- ----nn 6 06/03/1952 53 nn 56 ---- ----nn 106 ---- ----nn 7 05/18/1953 8 nn 57 ---- ----nn 107 ---- ----nn 8 10/23/1953 7 nn 58 ---- ----nn 108 ---- ----nn 9 07/23/1955 5 nn 59 ---- ----nn 109 ---- ----nn 10 07/29/1956 400 nn 60 ---- ----nn 110 ---- ----nn 11 05/09/1957 119 nn 61 ---- ----nn 111 ---- ----nn 12 05/14/1958 42 nn 62 ---- ----nn 112 ---- ----nn 13 06/21/1959 33 nn 63 ---- ----nn 113 ---- ----nn 14 05/05/1960 16 nn 64 ---- ----nn 114 ---- ----nn 15 07/08/1961 48 nn 65 ---- ----nn 115 ---- ----nn 16 04/29/1962 10 nn 66 --------nn 116 --------nn 17 06/16/1963 17 nn 67 ---- ----nn 117 ---- ----nn 18 04/16/1964 3 nn 68 --------nn 118 --------nn 19 06/15/1965 56 nn 69 ---- ----nn 119 ---- ----nn 20 08/01/1966 7 nn 70 ---- ----nn 120 ---- ----nn 21 07/19/1967 17 nn 71 ---- ----nn 121 ---- ----nn 22 06/08/1968 9 nn 72 ---- ----nn 122 ---- ----nn 23 05/09/1969 117 nn 73 ---- ----nn 123 ---- ----nn 24 06/11/1970 19 nn 74 ---- ----nn 124 ---- ----nn 25 05/02/1971 42 nn 75 ---- ----nn 125 ---- ----nn 26 08/16/1972 21 nn 76 ---- ----nn 126 ---- ----nn 27 05/07/1973 77 nn 77 ---- ----nn 127 ---- ----nn 28 06/09/1974 8 nn 78 ---- ----nn 128 ---- ----nn 29 06/02/1975 28 nn 79 ---- ----nn 129 ---- ----nn 30 07/31/1976 194 nn 80 --------nn 130 --------nn 31 07/24/1977 153 nn 81 ---- ----nn 131 ---- ----nn 32 05/19/1978 20 nn 82 ---- ----nn 132 ---- ----nn 33 06/17/1979 37 nn 83 ---- ----nn 133 ---- ----nn 34 05/13/1998 30 nn 84 ---- ----nn 134 ---- ----nn 35 05/27/1999 46 nn 85 ---- ----nn 135 ---- ----nn 36 04/23/2000 13 nn 86 ---- ----nn 136 ---- ----nn 37 07/05/2001 18 nn 87 ---- ----nn 137 ---- ----nn 38 05/24/2002 2 nn 88 ---- ----nn 138 ---- ----nn 39 04/15/2003 18 nn 89 ---- ----nn 139 ---- ----nn 40 07/19/2004 45 nn 90 ---- ----nn 140 ---- ----nn 41 05/31/2005 18 nn 91 --------nn 141 --------nn 42 08/21/2006 16 nn 92 ---- ----nn 142 ---- ----nn 43 08/02/2007 31 nn 93 ---- ----nn 143 ---- ----nn 44 06/05/2008 11 nn 94 ---- ----nn 144 ---- ----nn 45 05/02/2009 13 nn 95 ---- ----nn 145 ---- ----nn 46 05/18/2010 35 nn 96 ---- ----nn 146 ---- ----nn 47 05/23/2011 22 nn 97 ---- ----nn 147 ---- ----nn 48 07/07/2012 107 nn 98 ---- ----nn 148 ---- ----nn 49 09/13/2013 4,800 ny 99 ---- ----nn 149 ---- ----nn 50 --------nn 100 --------nn 150 --------nn Hi s t o r i c ? Ou t l i e r ? Hi s t o r i c ? Ou t l i e r ? Hi s t o r i c ? Ou t l i e r ? Natural Resources Conservation Service 6/20/2014 Log-Pearson Frequency Analysis Spreadsheet, Version 2.4, 3/2013 Page 3 of 3 Project:CO Front Range Floods of 2013 Streamgage:FISH CREEK NEAR ESTES PARK, CO Date:6/20/2014 Performed By:S. Yochum Discharge-Frequency, with Gage Skew FISH CREEK NEAR ESTES PARK, CO Discharge-Frequency, with Weighted Generalized Skew FISH CREEK NEAR ESTES PARK, CO 0 2,000 4,000 6,000 8,000 10,000 12,000 110100 Di s c h a r g e ( c f s ) Recurrence Interval (years) Log-Pearson LogPearson - Upper 95% Confidence Limit LogPearson - Lower 95% Confidence Limit Weibull Plotting Position 0 1,000 2,000 3,000 4,000 5,000 6,000 7,000 8,000 9,000 110100 Di s c h a r g e ( c f s ) Recurrence Interval (years) Log-PearsonLogPearson - Upper 95% Confidence LimitLogPearson - Lower 95% Confidence LimitWeibull Plotting Position Natural Resources Conservation Service 6/20/2014 Fish Creek Watershed Hydrology Evaluation Public Infrastructure Project August 2014 Page 34 Appendix E: HEC-SSP Output HE C - S S P 2 . 0 - F i s h C r e e k Fr e q u e n c y C u r v e f o r : F i s h C r e e k S e p t 2 4 0 0 c f s Pe r c e n t C h a n c e Ex c e e d a n c e Co m p u t e d C u r v e Fl o w i n c f s Ex p e c t e d P r o b . Fl o w i n c f s Co n f i d e n c e L i m i t s Fl o w i n c f s 0. 0 5 0. 9 5 0. 2 33 4 0 . 6 48 3 4 . 7 86 5 2 . 4 16 5 1 . 5 0. 5 16 8 7 . 6 22 0 4 . 6 38 7 2 . 3 90 9 . 3 1. 0 98 9 . 4 12 0 6 . 7 20 6 8 . 4 56 9 . 3 2. 0 56 8 . 9 65 5 . 5 10 8 2 . 4 34 9 . 5 5. 0 26 2 . 8 28 4 . 7 44 1 . 1 17 5 . 9 10 . 0 14 0 . 0 14 6 . 9 21 4 . 2 99 . 6 20 . 0 70 . 1 71 . 7 98 . 4 52 . 4 50 . 0 22 . 8 22 . 8 30 . 0 17 . 2 80 . 0 9. 5 9. 4 12 . 8 6. 7 90 . 0 6. 6 6. 5 9. 1 4. 5 95 . 0 5. 1 5. 0 7. 2 3. 3 99 . 0 3. 4 3. 3 5. 0 2. 1 Nu m b e r o f E v e n t s Ev e n t Nu m b e r Hi s t o r i c E v e n t s 0 Hi g h O u t l i e r s 1 Lo w O u t l i e r s 0 Ze r o O r M i s s i n g 0 Sy s t e m a t i c E v e n t s 55 Hi s t o r i c P e r i o d 67 Sy s t e m S t a t i s t i c s Lo g T r a n s f o r m : F l o w St a t i s t i c Va l u e Me a n 1. 4 3 4 St a n d a r d D e v 0. 5 3 2 St a t i o n S k e w 0. 8 8 8 Re g i o n a l S k e w 0. 8 1 9 We i g h t e d S k e w 0. 8 6 5 Ad o p t e d S k e w 0. 8 6 5 File: Fish_Creek_Sept_2400_cfs.rpt, Page: 1 −−−−−−−−−−−−−−−−−−−−−−−−−−−−−−− Bulletin 17B Frequency Analysis 26 Jun 2014 11:34 AM −−−−−−−−−−−−−−−−−−−−−−−−−−−−−−− −−− Input Data −−− Analysis Name: Fish Creek Sept 2400 cfs Description: Data Set Name: Fish Creek Sept 2400 cfs DSS File Name: R:\14.679.002 (Fish Creek)\Hydrology\HEC−SSP\Fish Creek\Fish_Creek\Fish_Creek.dss DSS Pathname: /FISH CREEK/ESTES PARK, CO./FLOW−ANNUAL PEAK/01jan1900/IR−CENTURY/USGS/ Report File Name: R:\14.679.002 (Fish Creek)\Hydrology\HEC−SSP\Fish Creek\Fish_Creek\Bulletin17bResults\Fish_Creek_Sept_2400_ XML File Name: R:\14.679.002 (Fish Creek)\Hydrology\HEC−SSP\Fish Creek\Fish_Creek\Bulletin17bResults\Fish_Creek_Sept_2400_cf Start Date: End Date: Skew Option: Use Weighted Skew Regional Skew: 0.819 Regional Skew MSE: 0.326 Plotting Position Type: Median Upper Confidence Level: 0.05 Lower Confidence Level: 0.95 Display ordinate values using 1 digits in fraction part of value −−− End of Input Data −−− −−− Preliminary Results −−− << Plotting Positions >> Fish Creek Sept 2400 cfs −−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−− | Events Analyzed | Ordered Events | | FLOW | Water FLOW Median | | Day Mon Year CFS | Rank Year CFS Plot Pos | |−−−−−−−−−−−−−−−−−−−−−−−−−−−|−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−| | 22 Jun 1947 53.0 | 1 2013 2,400.0* 1.26 | | 27 Apr 1948 14.0 | 2 1956 400.0 3.07 | | 06 Jun 1949 108.0 | 3 1976 194.0 4.87 | | 09 Jun 1950 5.0 | 4 1977 153.0 6.68 | | 03 Jun 1952 53.0 | 5 1957 119.0 8.48 | | 18 May 1953 8.0 | 6 1969 117.0 10.29 | | 23 Oct 1953 7.0 | 7 1995 111.0 12.09 | | 23 Jul 1955 5.0 | 8 1949 108.0 13.90 | | 29 Jul 1956 400.0 | 9 2012 107.0 15.70 | | 09 May 1957 119.0 | 10 1973 77.0 17.51 | | 14 May 1958 42.0 | 11 1965 56.0 19.31 | | 21 Jun 1959 33.0 | 12 1952 53.0 21.12 | | 05 May 1960 16.0 | 13 1947 53.0 22.92 | | 08 Jul 1961 48.0 | 14 1994 48.0 24.73 | | 29 Apr 1962 10.0 | 15 1961 48.0 26.53 | | 16 Jun 1963 17.0 | 16 1999 46.0 28.34 | | 16 Apr 1964 3.0 | 17 2004 45.0 30.14 | | 15 Jun 1965 56.0 | 18 1971 42.0 31.95 | | 01 Aug 1966 7.0 | 19 1958 42.0 33.75 | | 19 Jul 1967 17.0 | 20 1979 37.0 35.56 | | 08 Jun 1968 9.0 | 21 2010 35.0 37.36 | | 09 May 1969 117.0 | 22 1959 33.0 39.17 | | 11 Jun 1970 19.0 | 23 2007 31.0 40.97 | | 02 May 1971 42.0 | 24 1998 30.0 42.78 | | 16 Aug 1972 21.0 | 25 1975 28.0 44.58 | | 07 May 1973 77.0 | 26 1997 23.0 46.39 | | 09 Jun 1974 8.0 | 27 1991 23.0 48.19 | | 02 Jun 1975 28.0 | 28 2011 22.0 50.00 | | 31 Jul 1976 194.0 | 29 1990 22.0 51.81 | | 24 Jul 1977 153.0 | 30 1972 21.0 53.61 | | 19 May 1978 20.0 | 31 1996 20.0 55.42 | File: Fish_Creek_Sept_2400_cfs.rpt, Page: 2 | 17 Jun 1979 37.0 | 32 1978 20.0 57.22 | | 25 Apr 1990 22.0 | 33 1970 19.0 59.03 | | 02 Jun 1991 23.0 | 34 2005 18.0 60.83 | | 17 May 1993 7.0 | 35 2003 18.0 62.64 | | 13 Aug 1994 48.0 | 36 2001 18.0 64.44 | | 30 May 1995 111.0 | 37 1967 17.0 66.25 | | 26 May 1996 20.0 | 38 1963 17.0 68.05 | | 08 Jun 1997 23.0 | 39 2006 16.0 69.86 | | 13 May 1998 30.0 | 40 1960 16.0 71.66 | | 27 May 1999 46.0 | 41 1948 14.0 73.47 | | 23 Apr 2000 13.0 | 42 2009 13.0 75.27 | | 05 Jul 2001 18.0 | 43 2000 13.0 77.08 | | 24 May 2002 2.0 | 44 2008 11.0 78.88 | | 15 Apr 2003 18.0 | 45 1962 10.0 80.69 | | 19 Jul 2004 45.0 | 46 1968 9.0 82.49 | | 31 May 2005 18.0 | 47 1974 8.0 84.30 | | 21 Aug 2006 16.0 | 48 1953 8.0 86.10 | | 02 Aug 2007 31.0 | 49 1993 7.0 87.91 | | 05 Jun 2008 11.0 | 50 1966 7.0 89.71 | | 02 May 2009 13.0 | 51 1954 7.0 91.52 | | 18 May 2010 35.0 | 52 1955 5.0 93.32 | | 23 May 2011 22.0 | 53 1950 5.0 95.13 | | 07 Jul 2012 107.0 | 54 1964 3.0 96.93 | | 13 Sep 2013 2,400.0 | 55 2002 2.0 98.74 | |−−−−−−−−−−−−−−−−−−−−−−−−−−−|−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−| * Outlier << Skew Weighting >> −−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−− Based on 55 events, mean−square error of station skew = 0.164 Mean−square error of regional skew = 0.326 −−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−− << Frequency Curve >> Fish Creek Sept 2400 cfs −−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−− | Computed Expected | Percent | Confidence Limits | | Curve Probability | Chance | 0.05 0.95 | | FLOW, CFS | Exceedance | FLOW, CFS | |−−−−−−−−−−−−−−−−−−−−−−−−−|−−−−−−−−−−−−−|−−−−−−−−−−−−−−−−−−−−−−−−−| | 3,340.6 4,834.7 | 0.2 | 8,652.4 1,651.5 | | 1,687.6 2,204.6 | 0.5 | 3,872.3 909.3 | | 989.4 1,206.7 | 1.0 | 2,068.4 569.3 | | 568.9 655.5 | 2.0 | 1,082.4 349.5 | | 262.8 284.7 | 5.0 | 441.1 175.9 | | 140.0 146.9 | 10.0 | 214.2 99.6 | | 70.1 71.7 | 20.0 | 98.4 52.4 | | 22.8 22.8 | 50.0 | 30.0 17.2 | | 9.5 9.4 | 80.0 | 12.8 6.7 | | 6.6 6.5 | 90.0 | 9.1 4.5 | | 5.1 5.0 | 95.0 | 7.2 3.3 | | 3.4 3.3 | 99.0 | 5.0 2.1 | |−−−−−−−−−−−−−−−−−−−−−−−−−|−−−−−−−−−−−−−|−−−−−−−−−−−−−−−−−−−−−−−−−| << Systematic Statistics >> Fish Creek Sept 2400 cfs −−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−− | Log Transform: | | | FLOW, CFS | Number of Events | |−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−|−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−| | Mean 1.434 | Historic Events 0 | | Standard Dev 0.532 | High Outliers 0 | | Station Skew 0.888 | Low Outliers 0 | | Regional Skew 0.819 | Zero Events 0 | File: Fish_Creek_Sept_2400_cfs.rpt, Page: 3 | Weighted Skew 0.865 | Missing Events 0 | | Adopted Skew 0.865 | Systematic Events 55 | |−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−|−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−| −−− End of Preliminary Results −−− −−−−−−−−−−−−−−−−−−−−−−− << High Outlier Test >> −−−−−−−−−−−−−−−−−−−−−−− Based on 55 events, 10 percent outlier test deviate K(N) = 2.804 Computed high outlier test value = 843.62 1 high outlier(s) identified above test value of 843.62 * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * Note − Collection of historical information and * * comparison with similar data should be explored, * * if not incorporated in this analysis. * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * Statistics and frequency curve adjusted for 1 high outlier(s) −−−−−−−−−−−−−−−−−−−−−− << Low Outlier Test >> −−−−−−−−−−−−−−−−−−−−−− Based on 55 events, 10 percent outlier test deviate K(N) = 2.804 Computed low outlier test value = 0.88 0 low outlier(s) identified below test value of 0.88 −−− Final Results −−− << Plotting Positions >> Fish Creek Sept 2400 cfs −−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−− | Events Analyzed | Ordered Events | | FLOW | Water FLOW Median | | Day Mon Year CFS | Rank Year CFS Plot Pos | |−−−−−−−−−−−−−−−−−−−−−−−−−−−|−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−| | 22 Jun 1947 53.0 | 1 2013 2,400.0* 1.04 | | 27 Apr 1948 14.0 | 2 1956 400.0 2.69 | | 06 Jun 1949 108.0 | 3 1976 194.0 4.50 | | 09 Jun 1950 5.0 | 4 1977 153.0 6.31 | | 03 Jun 1952 53.0 | 5 1957 119.0 8.13 | | 18 May 1953 8.0 | 6 1969 117.0 9.94 | | 23 Oct 1953 7.0 | 7 1995 111.0 11.75 | | 23 Jul 1955 5.0 | 8 1949 108.0 13.57 | | 29 Jul 1956 400.0 | 9 2012 107.0 15.38 | | 09 May 1957 119.0 | 10 1973 77.0 17.19 | | 14 May 1958 42.0 | 11 1965 56.0 19.01 | | 21 Jun 1959 33.0 | 12 1952 53.0 20.82 | | 05 May 1960 16.0 | 13 1947 53.0 22.63 | | 08 Jul 1961 48.0 | 14 1994 48.0 24.45 | | 29 Apr 1962 10.0 | 15 1961 48.0 26.26 | | 16 Jun 1963 17.0 | 16 1999 46.0 28.07 | | 16 Apr 1964 3.0 | 17 2004 45.0 29.89 | | 15 Jun 1965 56.0 | 18 1971 42.0 31.70 | | 01 Aug 1966 7.0 | 19 1958 42.0 33.51 | | 19 Jul 1967 17.0 | 20 1979 37.0 35.33 | | 08 Jun 1968 9.0 | 21 2010 35.0 37.14 | | 09 May 1969 117.0 | 22 1959 33.0 38.95 | | 11 Jun 1970 19.0 | 23 2007 31.0 40.77 | | 02 May 1971 42.0 | 24 1998 30.0 42.58 | | 16 Aug 1972 21.0 | 25 1975 28.0 44.39 | | 07 May 1973 77.0 | 26 1997 23.0 46.21 | | 09 Jun 1974 8.0 | 27 1991 23.0 48.02 | | 02 Jun 1975 28.0 | 28 2011 22.0 49.84 | | 31 Jul 1976 194.0 | 29 1990 22.0 51.65 | | 24 Jul 1977 153.0 | 30 1972 21.0 53.46 | | 19 May 1978 20.0 | 31 1996 20.0 55.28 | File: Fish_Creek_Sept_2400_cfs.rpt, Page: 4 | 17 Jun 1979 37.0 | 32 1978 20.0 57.09 | | 25 Apr 1990 22.0 | 33 1970 19.0 58.90 | | 02 Jun 1991 23.0 | 34 2005 18.0 60.72 | | 17 May 1993 7.0 | 35 2003 18.0 62.53 | | 13 Aug 1994 48.0 | 36 2001 18.0 64.34 | | 30 May 1995 111.0 | 37 1967 17.0 66.16 | | 26 May 1996 20.0 | 38 1963 17.0 67.97 | | 08 Jun 1997 23.0 | 39 2006 16.0 69.78 | | 13 May 1998 30.0 | 40 1960 16.0 71.60 | | 27 May 1999 46.0 | 41 1948 14.0 73.41 | | 23 Apr 2000 13.0 | 42 2009 13.0 75.22 | | 05 Jul 2001 18.0 | 43 2000 13.0 77.04 | | 24 May 2002 2.0 | 44 2008 11.0 78.85 | | 15 Apr 2003 18.0 | 45 1962 10.0 80.66 | | 19 Jul 2004 45.0 | 46 1968 9.0 82.48 | | 31 May 2005 18.0 | 47 1974 8.0 84.29 | | 21 Aug 2006 16.0 | 48 1953 8.0 86.10 | | 02 Aug 2007 31.0 | 49 1993 7.0 87.92 | | 05 Jun 2008 11.0 | 50 1966 7.0 89.73 | | 02 May 2009 13.0 | 51 1954 7.0 91.54 | | 18 May 2010 35.0 | 52 1955 5.0 93.36 | | 23 May 2011 22.0 | 53 1950 5.0 95.17 | | 07 Jul 2012 107.0 | 54 1964 3.0 96.98 | | 13 Sep 2013 2,400.0 | 55 2002 2.0 98.80 | |−−−−−−−−−−−−−−−−−−−−−−−−−−−|−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−| | Note: Plotting positions based on historic period (H) = 67 | | Number of historic events plus high outliers (Z) = 1 | | Weighting factor for systematic events (W) = 1.2222 | −−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−− * Outlier << Skew Weighting >> −−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−− Based on 55 events, mean−square error of station skew = 0.164 Mean−square error of regional skew = 0.326 −−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−− << Frequency Curve >> Fish Creek Sept 2400 cfs −−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−− | Computed Expected | Percent | Confidence Limits | | Curve Probability | Chance | 0.05 0.95 | | FLOW, CFS | Exceedance | FLOW, CFS | |−−−−−−−−−−−−−−−−−−−−−−−−−|−−−−−−−−−−−−−|−−−−−−−−−−−−−−−−−−−−−−−−−| | 3,340.6 4,834.7 | 0.2 | 8,652.4 1,651.5 | | 1,687.6 2,204.6 | 0.5 | 3,872.3 909.3 | | 989.4 1,206.7 | 1.0 | 2,068.4 569.3 | | 568.9 655.5 | 2.0 | 1,082.4 349.5 | | 262.8 284.7 | 5.0 | 441.1 175.9 | | 140.0 146.9 | 10.0 | 214.2 99.6 | | 70.1 71.7 | 20.0 | 98.4 52.4 | | 22.8 22.8 | 50.0 | 30.0 17.2 | | 9.5 9.4 | 80.0 | 12.8 6.7 | | 6.6 6.5 | 90.0 | 9.1 4.5 | | 5.1 5.0 | 95.0 | 7.2 3.3 | | 3.4 3.3 | 99.0 | 5.0 2.1 | |−−−−−−−−−−−−−−−−−−−−−−−−−|−−−−−−−−−−−−−|−−−−−−−−−−−−−−−−−−−−−−−−−| << Systematic Statistics >> Fish Creek Sept 2400 cfs −−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−− | Log Transform: | | | FLOW, CFS | Number of Events | |−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−|−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−| Fish Creek Watershed Hydrology Evaluation Public Infrastructure Project August 2014 Page 36 Appendix F: Sub Basin Map Fis h C r e e k £¤36 £¤36 ¬«7 ¬«7 Fish Creek Watershed15.9 Sq. Mi. BB AA BB AA BB AA BB AA BB AA BB AA BB AA BB AA BBAA BB AA BB AA BB AA BB AA BB AA BB AA BB AA BB AA BB AA BB AA L= 1 7 3 5 8 S = 0 . 1 8 L= 14 8 1 1 S = 0 . 1 6 L = 1 2 2 9 3 S = 0 . 2 2 L= 1 1 4 6 1 S = 0 . 1 4 L= 1 2 9 1 9 S = 0 . 1 6 L = 1 1 3 5 1 S = 0 . 2 4 L = 1 1 9 7 5 S = 0 . 1 6 L= 9 2 7 3 S = 0 . 1 7 L= 9040 S=0.13 L= 8520 S=0.08 L = 9 7 1 6 S = 0 . 1 6 L= 8 1 3 7 S = 0 . 1 4 L= 11149 S=0.16 L = 9 5 5 7 S = 0 . 1 3 L = 8 8 6 4 S = 0 . 1 5 L= 5607 S=0.22 L= 6900 S= 0 . 0 6 L= 4568 S=0.11 C L = 1 0 3 7 3 CL= 7 6 5 6 CL = 6 2 0 9 C L = 6 9 1 0 CL = 5 2 0 5 CL = 5 6 9 6 CL= 4 1 8 8 CL= 4126 CL= 3548 CL= 3 5 8 0 CL= 3 5 9 8 CL= 3 5 1 4 CL = 3 8 5 6 CL = 3 0 8 6 CL= 2 9 7 1 CL= 3008 CL= 30 5 0 CL= 19 5 4 CL= 1 4 3 7 Area= 847 acCN= 68 Area= 837 acCN= 68 Area= 721 acCN= 69 Area= 677 acCN= 75 Area= 676 acCN= 68 Area= 659 acCN= 62 Area= 652 acCN= 65 Area= 638 acCN= 64 Area= 632 acCN= 78 Area= 590 acCN= 73 Area= 590 acCN= 72Area= 567 acCN= 62 Area= 516 acCN= 71 Area= 405 acCN= 65 Area= 371 acCN= 65 Area= 320 acCN= 78 Area= 164 acCN= 77 Area= 146 acCN= 73 Area= 160 acCN= 81 Copyright:© 2013 National Geographic Society, i-cubed FI L E : G : \ g i s _ p r o j e c t s \ F i s h _ C r e e k _ E s t e s _ P a r k \ a c t i v e \ a p p s \ F i s h _ C r e e k _ S u b _ B a s i n _ M a p . m x d , 6 / 2 4 / 2 0 1 4 , S c o t t _ S c h r e i b e r Sub Basin Map o 0 0.25 0.5Miles Fish Creek - Estes Park, CO Legend Flow Break Point Types Sheet Flow/Shallow Concentrated Flow Shallow Concentrated Flow/Channel Flow Centroid Longest Flow Path Longest Flow Path StreamStats Basin Sub Basins Fish Creek Watershed Hydrology Evaluation Public Infrastructure Project August 2014 Page 38 Appendix G: Sub Basin Characteristics Table Percent Impervious Longest Watercourse Longest Watercourse Opposite Centroid Longest Watercourse Elevation Change Slope of Longest Watercourse CWCB Lag Slope of Longest Watercourse Synder Lag (C=2.2)[sq mi] [%] [mi] [mi] [ft] [ft/mi] [hr] [ft/ft] [hr]W160 0.63 64.7 0.5% 2.33 0.99 2,760 1,185 1.4 0.22 2.8W220 1.13 69.0 0.0% 3.29 1.96 3,104 944 2.0 0.18 3.9W310 1.31 68.2 1.7% 2.27 1.08 1,911 843 1.5 0.16 2.9W470 0.99 77.7 4.2% 1.68 0.67 1,296 772 1.1 0.15 2.3W510 1.02 64.5 1.6% 2.15 0.79 2,699 1,255 1.2 0.24 2.6W520 1.06 68.1 1.3% 2.11 0.56 1,751 829 1.2 0.16 2.3W620 1.32 68.7 1.3% 1.76 0.68 1,563 890 1.1 0.17 2.3W660 0.25 80.4 10.6% 1.15 0.37 384 333 1.0 0.06 1.7W710 0.92 73.2 4.3% 1.61 0.67 715 443 1.2 0.08 2.3W720 0.50 77.5 4.3% 1.31 0.68 395 303 1.2 0.06 2.1W760 0.92 71.1 0.3% 2.17 1.18 1,653 762 1.5 0.14 2.9W820 0.81 70.3 6.3% 1.84 0.58 1,582 860 1.1 0.16 2.2W860 0.23 72.2 9.4% 0.87 0.27 507 586 0.7 0.11 1.4W910 0.89 62.4 1.0% 2.45 1.31 2,054 840 1.6 0.16 3.1W920 0.26 76.6 0.1% 1.06 0.57 1,218 1,147 0.9 0.22 1.9W960 1.06 74.9 8.7% 1.71 0.73 1,213 708 1.2 0.13 2.4W970 0.58 65.0 0.6% 1.54 0.78 1,109 720 1.2 0.14 2.3W1060 1.00 63.4 0.0% 2.81 1.45 2,409 859 1.7 0.16 3.4W1070 1.03 61.4 0.0% 1.81 0.58 1,260 696 1.1 0.13 2.2 Drainage Area CWCB Lag Synder Lag Basin Curve Number Fish Creek Watershed Hydrology Evaluation Public Infrastructure Project August 2014 Page 40 Appendix H: Design Point Map F i s h Cr e e k £¤34 £¤36 £¤34 £¤36 ¬«7 ¬«7 Fish Creek Watershed 15.9 Sq. Mi. Upstream of Rockwood Lane Q2 = 10 cfs Q10 = 23 cfs Q50 = 111 cfs Q100 = 178 cfs Upstream of Little Valley Road Q2 = 14 cfs Q10 = 58 cfs Q50 = 266 cfs Q100 = 426 cfs Upstream of Scott Avenue Q2 = 18 cfs Q10 = 141 cfs Q50 = 515 cfs Q100 = 786 cfs Upstream of Johnsen Lane Q2 = 20 cfs Q10 = 154 cfs Q50 = 568 cfs Q100 = 870 cfs Downstream of Powelly Lane Q2 = 22 cfs Q10 = 177 cfs Q50 = 637 cfs Q100 = 970 cfs At Entrance to Lake Estes Q2 = 23 cfs Q10 = 181 cfs Q50 = 651 cfs Q100 = 990 cfs Sources: Esri, HERE, DeLorme, TomTom, Intermap, increment P Corp., GEBCO, USGS, FAO, NPS, NRCAN, GeoBase, IGN, Kadaster NL, Ordnance Survey, Esri Japan, METI, Esri China (Hong Kong), swisstopo,MapmyIndia, © OpenStreetMap contributors, and the GIS User Community, Copyright:© 2013 Esri, DeLorme, NAVTEQ, TomTom, Copyright:© 2013 National Geographic Society, i-cubed FI L E : G : \ g i s _ p r o j e c t s \ F i s h _ C r e e k _ E s t e s _ P a r k \ a c t i v e \ a p p s \ F i s h _ C r e e k _ D e s i g n _ P o i n t _ M a p . m x d , 7 / 2 / 2 0 1 4 , h u n g t e n g _ h o Design Point Map o 0 0.25 0.5Miles Fish Creek - Estes Park, CO