View source for Chatfield Reservoir

{{Use mdy dates|date=February 2025}}
{{Infobox body of water
| name = Chatfield Reservoir
| image = Chatfield State Park.JPG
| caption = Chatfield Reservoir
| image_bathymetry = 
| caption_bathymetry = 
| location = [[Douglas County, Colorado|Douglas]] and [[Jefferson County, Colorado|Jefferson]] counties, [[Colorado]], [[United States|U.S.]]
| coords = {{coord|39.547206|N|105.065002|W|format=dms|region:US-CO_type:waterbody|display=inline,title}}
| type = [[reservoir]]
| inflow = [[South Platte River]]
| outflow = South Platte River
| catchment = {{convert|3018|sqmi|km2|abbr=on}}
| basin_countries = United States
| length = 
| width = 
| area = {{convert|1500|acre|abbr=on}} (Normal pool)<br>{{convert|4822|acre|abbr=on}} (Max. Pool)
| depth = 
| max-depth = {{convert|47|m|abbr=on}}
| volume = 
| residence_time = 
| shore = 
| elevation = 
| islands = 
| cities = 
<!--      Map      -->
| pushpin_map             = Colorado#USA
| pushpin_label_position  = 
| pushpin_map_alt         = Location of Chatfield Reservoir in Colorado, USA.
| pushpin_map_caption     = 
<!--   Below       -->  
| website            = 
| reference          = 
}}
{{Infobox dam
| name                 = Chatfield Dam
| name_official        = 
| image                = USACE Chatfield dam and reservoir.jpg
| image_size           = 
| image_caption        = Chatfield Dam
| image_alt            = 
| location_map         = Colorado
| location_map_size    = 
| location_map_caption = Location of Chatfield Dam and Reservoir in Colorado
| coordinates          = 
| country              = 
| location             = 
| status               = O
| construction_began   = {{Start date and age|1967}}
| opening              = {{Start date and age|1975}}
| demolished           = 
| cost                 = 
| owner                = [[Image:United States Army Corps of Engineers logo.svg|24px]] [[U.S. Army Corps of Engineers]], Omaha District<ref>{{Cite web|url=https://www.nwo.usace.army.mil/Media/Fact-Sheets/Fact-Sheet-Article-View/Article/487647/chatfield-project-statistics/|title=Chatfield Project Statistics}}</ref>
| dam_type             = Rolled earth fill
| dam_height           = {{Convert|147|ft|m|0|abbr=on}}
| dam_height_thalweg   =
| dam_height_foundation=
| dam_length           = {{Convert|13136|ft|m|0|abbr=on}}
| dam_width_crest      = {{Convert|30|ft|m|0|abbr=on}}
| dam_width_base       = 
| dam_volume           = {{Convert|17255100|cuyd|m3|0|abbr=on}}
| dam_elevation_crest  =
| dam_crosses          = 
| spillway_count       = 
| spillway_type        = 
| spillway_capacity    = 
| res_name             = 
| res_capacity_total   = {{Convert|355000|acre.ft|m3|0|abbr=on}}
| res_capacity_active  =
| res_capacity_inactive= {{Convert|27076|acre.ft|m3|0|abbr=on}}
| res_catchment        = 
| res_surface          = 
| res_elevation        = {{Convert|5432|ft|m|0|abbr=on}} - {{Convert|5500|ft|m|0|abbr=on}} [[Sea level|MSL]]
| res_max_depth        = 
| res_max_length       = {{Convert|2|mi|km|0|abbr=on}}
| res_max_width        =
| res_tidal_range      = 
| plant_operator       = 
| plant_commission     = 
| plant_decommission   = 
| plant_type           = 
| plant_turbines       = 
| plant_capacity       = 
| plant_annual_gen     = 
| website              = 
| extra                = 
}}
[[File:Chatfield Reservoir - balloon and cyclist - Aug 2020.jpg|thumb|Balloon and cyclist over the Chatfield State Park]]
'''Chatfield Dam and Reservoir''' is a dam and artificial lake located on the [[South Platte River]], south of [[Littleton, Colorado|Littleton]], [[Colorado]]. The dam and reservoir were built by the [[United States Army Corps of Engineers]] as a response to the disastrous flood of 1965. In addition to its primary purpose of [[flood control]], it serves as one of many [[water supply]] reservoirs for the city of [[Denver, Colorado]].

==Construction==
In 1966, the [[United States Atomic Energy Commission|U.S. Atomic Energy Commission]] projected a total federal cost of $74 million.<ref>{{cite web |url=https://library.cqpress.com/cqalmanac/document.php?id=cqal66-1301233# |title=CQ Alamanc 1966 |author=<!--Staff writer(s); no by-line.--> |date=1967 |website=cqpress.com |publisher=Congressional Quarterly |access-date=15 June 2016}}</ref> Construction of the project was begun in 1967 and the dam was completed in 1975.

The massive breastworks of the dam measure approximately {{convert|13136|ft|m}} in length with a maximum height of the dam of {{convert|135|ft|m}} above the streambed. The normal depth of the lake is {{convert|59|ft|m}} at its deepest point. This means the dam towers {{convert|88|ft|m}} above the mean surface of the reservoir.

The lake drains an area of more than 3,000 square miles (8,000&nbsp;km<sup>2</sup>). The 1,500 acre (6&nbsp;km<sup>2</sup>) lake has a conservation storage capacity of {{convert|27,000|acre.ft|km3|abbr=on}} with a flood-control pool of over {{convert|350000|acre feet|km3|abbr=on}}.

The reservoir inundated the abandoned roadbed of the [[Colorado and Southern Railway]], a historic [[Narrow-gauge railroads in the United States|narrow gauge]] line active between 1874 and 1942. Until 1899, it was part of the [[Denver, South Park and Pacific Railroad]]. The roadbed is still visible extending from the southern shore into the water just west of the inlet.

===Chatfield Reservoir Reallocation Project===
The Chatfield Reservoir Reallocation Project, a {{US$|171}}{{nbsp}}million construction project that took place between 2017 and 2020, created an additional {{convert|20600|acre.ft|abbr=off|sp=us}} of water storage in the reservoir, raising its level by about {{convert|12|ft|sp=us|abbr=off}}. The project involved moving some of the surrounding park's facilities back from the new, higher lake levels.<ref>{{cite web |url=https://cwcb.colorado.gov/news-article/partners-finalize-chatfield-reservoir-reallocation-project |title=State and Federal Partners Finalize Chatfield Reservoir Reallocation Project with Environmental, Agricultural, Recreational Benefits |author=<!--Not stated--> |date=2020-05-13 |website=Colorado Water Conservation Board |publisher=Colorado Department of Natural Resources |access-date=2021-08-05 |quote=}}</ref><ref>{{cite news |last=Rubino |first=Joe |date=2017-06-27 |title=Chatfield Reservoir expansion project will start this fall |url=http://www.denverpost.com/2017/06/27/chatfield-reservoir-expansion-project/ |work=The Denver Post |access-date=2017-07-19 }}</ref><ref>{{cite web |url=http://chatfieldreallocation.org/overview/ |title=Project Overview |author=<!--Not stated--> |publisher=Chatfield Storage Reallocation Project |access-date=2017-07-19 }}</ref>

Precautions were put into place during the Reallocation Project to adjust the timing and amount of water releases in a good faith manner in order to avoid impacting the walleye and smallmouth bass spawning during the spring. Best management practices were also used to minimize the spread of noxious and invasive weeds during water level fluctuations and soil disturbances due to the new construction.<ref>{{Cite web |title=Fish, Wildlife, and Recreation Mitigation Plan |url=https://chatfieldreallocation.org/wp-content/uploads/2017/04/fwrMitigationPlan.pdf |access-date=June 4, 2025 |website=Chatfield Storage Reallocation Project}}</ref>

On May 19, 2023, a new high water mark milestone was achieved as part of the Reallocation Project - reaching 5,444 feet above sea level. This increase in the water level has expanded the overall reservoir footprint resulting in some of the cottonwood trunks to now be below the water's surface and providing more locations for kayaking and paddle boarding.<ref>{{Cite web |title=Introducing: Your new, expanded Chatfield Reservoir |url=https://www.denverwater.org/tap/introducing-your-new-expanded-chatfield-reservoir?size=n_21_n |archive-url=http://web.archive.org/web/20240422171704/https://www.denverwater.org/tap/introducing-your-new-expanded-chatfield-reservoir?size=n_21_n |archive-date=2024-04-22 |access-date=2025-06-04 |website=Denver Water |language=en}}</ref>

=== Flood Risk Mitigation ===
During normal operations, the water released from Chatfield Reservoir to downstream users is less than 500 cubic feet of water ([[Cubic foot#Cubic foot per second and related flow rates|cfs]]) per second. During times of flood risk due to high snow runoff, the outlet structure can release up to 8,400 cfs. The structural design of the spillway was created to pass up to an additional 184,000 cfs in extreme flooding risk.<ref>{{Cite web |title=Omaha District > Missions > Dam and Lake Projects > Tri-Lakes Projects > Chatfield Dam |url=https://www.nwo.usace.army.mil/Missions/Dam-and-Lake-Projects/Tri-Lakes-Projects/Chatfield-Dam/ |archive-url=http://web.archive.org/web/20250524225829/https://www.nwo.usace.army.mil/Missions/Dam-and-Lake-Projects/Tri-Lakes-Projects/Chatfield-Dam/ |archive-date=2025-05-24 |access-date=2025-06-04 |website=www.nwo.usace.army.mil |language=en-US}}</ref>

==Chatfield State Park==
The reservoir is surrounded by [[Chatfield State Park]], a recreation area with boating, horseback riding, swimming, paddle boarding, fishing, biking, horseback riding, and camping. A secondary inflow from the south is [[Plum Creek (Douglas County, Colorado)|Plum Creek]]. A tertiary inflow from the west is Deer Creek.

There are 212 bird species that are frequently found at Chatfield Reservoir. These birds either permanently live there or just go there to rest after long migrations. There is a Chatfield bird watch list that anyone can access. The [[bald eagle]], [[American white pelican|white pelican]] and [[burrowing owl]] have been seen.<ref>{{cite web|author=<!--Not stated--> |title=Nature|url=http://cpw.state.co.us/placestogo/parks/Chatfield/Pages/Nature.aspx|website=Colorado Parks and Wildlife|accessdate=2014-10-21}}</ref>

== Environmental Issues ==
The Chatfield Reservoir is routinely monitored in three areas: the Reservoir Centroid, the South Platte Arm, and the Plum Creek Arm, which is overseen by the [[Colorado Department of Public Health and Environment]]. The water is tested for unhealthy levels of phosphorus, chlorophyll-a, nutrients, constituents of concern, total suspended solids, temperature, and specific conductance that could cause harm to the people and animals that use the body of water.<ref>{{cite web | url=https://www.chatfieldwatershedauthority.org/monitoring | title=Monitoring }}</ref>

There have been several irregular test results for E. coli bacteria in recent years that ended up temporarily closing the swim beach at Chatfield State Park.<ref>{{cite web | url=https://www.denverpost.com/2019/07/17/cherry-creek-state-park-swim-beach-closed-due-to-e-coli-as-chatfield-reopens-following-one-day-closure-2/ | title=Cherry Creek State Park swim beach closed due to E. Coli as Chatfield reopens following one-day closure | date=17 July 2019 }}</ref> Generally, closures are not a common occurrence, but can be caused by fecal waste from wildlife, run-off from urban areas, or excessive run-off from recent rainfall.<ref>{{cite web | url=https://www.denverpost.com/2021/07/07/cherry-creek-state-park-swim-beach-closed-due-to-e-coli-as-chatfield-reopens-following-one-day-closure/ | title=Cherry Creek State Park swim beach closed due to E. Coli as Chatfield reopens following one-day closure | date=7 July 2021 }}</ref>

The Colorado Senate Bill SB23-267 was signed by Colorado Governor [[Jared Polis]] on June 6, 2023, creating the Chatfield State Park Water Quality Fee. The fee was created to help fund the Chatfield Watershed Plan which identifies opportunities to address chemical, physical and biological pollutants. Pollutants such as runoff from wildfire burn areas, phosphorus outbreaks from degraded upstream banks, and runoff from nearby agricultural land and septic systems.<ref>https://leg.colorado.gov/sites/default/files/2023a_267_signed.pdf {{Bare URL PDF|date=August 2024}}</ref>

==See also==
*[[Cherry Creek State Park|Cherry Creek Dam & Reservoir]]
*[[Bear Creek Dam (Colorado)|Bear Creek & Reservoir]]

==References==
{{Reflist}}

==External links==
*[https://www.nwo.usace.army.mil/Missions/Dam-and-Lake-Projects/Tri-Lakes-Projects/ Tri-Lakes Projects] (Official site) - [[U.S. Army Corps of Engineers]]
*[https://cpw.state.co.us/placestogo/parks/Chatfield/Documents/ChatfieldAreaMap.pdf Chatfield Lake Area Map] - Colorado Parks & Wildlife
*[https://web.archive.org/web/20070325051619/http://www.fishexplorer.com/fx/lakedet.asp?lid=2108 Chatfield conditions and fishing reports]
*[http://chatfieldreallocation.org/ Chatfield Storage Reallocation Project website]

{{Omaha District dams}}

{{authority control}}

[[Category:Reservoirs in Colorado]]
[[Category:Bodies of water of Douglas County, Colorado]]
[[Category:Tourist attractions in Jefferson County, Colorado]]
[[Category:Protected areas of Jefferson County, Colorado]]
[[Category:United States Army Corps of Engineers dams]]
[[Category:Dams in Colorado]]
[[Category:Buildings and structures in Douglas County, Colorado]]
[[Category:Buildings and structures in Jefferson County, Colorado]]
[[Category:Dams completed in 1975]]