Chatfield Reservoir - balloon and cyclist - Aug 2020

Chatfield Dam and Reservoir is a dam and artificial lake located on the

South Platte River The South Platte River is one of the two principal tributaries of the Platte River. Flowing through the U.S. states of Colorado and Nebraska, it is itself a major river of the American Midwestern United States, Midwest and the American Sou ...

, south of Littleton,

Colorado Colorado is a U.S. state, state in the Western United States. It is one of the Mountain states, sharing the Four Corners region with Arizona, New Mexico, and Utah. It is also bordered by Wyoming to the north, Nebraska to the northeast, Kansas ...

. The dam and reservoir were built by the

United States Army Corps of Engineers The United States Army Corps of Engineers (USACE) is the military engineering branch of the United States Army. A direct reporting unit (DRU), it has three primary mission areas: Engineer Regiment, military construction, and civil wo ...

as a response to the disastrous flood of 1965. In addition to its primary purpose of

flood control Flood management or flood control are methods used to reduce or prevent the detrimental effects of flood waters. Flooding can be caused by a mix of both natural processes, such as extreme weather upstream, and human changes to waterbodies and ru ...

, it serves as one of many

water supply Water supply is the provision of water by public utilities, commercial organisations, community endeavors or by individuals, usually via a system of pumps and pipes. Public water supply systems are crucial to properly functioning societies. Th ...

reservoirs for the city of

Denver, Colorado Denver ( ) is a List of municipalities in Colorado#Consolidated city and county, consolidated city and county, the List of capitals in the United States, capital and List of municipalities in Colorado, most populous city of the U.S. state of ...

Construction

In 1966, the U.S. Atomic Energy Commission projected a total federal cost of $74 million. Construction of the project was begun in 1967 and the dam was completed in 1975. The massive breastworks of the dam measure approximately in length with a maximum height of the dam of above the streambed. The normal depth of the lake is at its deepest point. This means the dam towers above the mean surface of the reservoir. The lake drains an area of more than 3,000 square miles (8,000 km²). The 1,500 acre (6 km²) lake has a conservation storage capacity of with a flood-control pool of over . The reservoir inundated the abandoned roadbed of the

Colorado and Southern Railway The Colorado and Southern Railway was an American Railroad classes#Class I, Class I railroad in the western United States that operated independently from 1898 to 1908, then as part of the Chicago, Burlington and Quincy Railroad until it was ...

, a historic

narrow gauge A narrow-gauge railway (narrow-gauge railroad in the US) is a railway with a track gauge (distance between the rails) narrower than . Most narrow-gauge railways are between and . Since narrow-gauge railways are usually built with Minimum railw ...

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 million construction project that took place between 2017 and 2020, created an additional of water storage in the reservoir, raising its level by about . The project involved moving some of the surrounding park's facilities back from the new, higher lake levels. 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. 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.

Flood Risk Mitigation

During normal operations, the water released from Chatfield Reservoir to downstream users is less than 500 cubic feet of water ( 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.

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. 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 The bald eagle (''Haliaeetus leucocephalus'') is a bird of prey found in North America. A sea eagle, it has two known subspecies and forms a species pair with the white-tailed eagle (''Haliaeetus albicilla''), which occupies the same niche ...

, white pelican and

burrowing owl The burrowing owl (''Athene cunicularia''), also called the shoco, is a small, long-legged, primarily terrestrial—though not flightless—species of owl native to the open landscapes of North and South America. They are typically found in gra ...

have been seen.

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. 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. 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. The Colorado Senate Bill SB23-267 was signed by Colorado Governor

Jared Polis Jared Schutz Polis ( ; ; born May 12, 1975) is an American politician and businessman serving as the 43rd governor of Colorado since 2019. He served one term on the Colorado State Board of Education from 2001 to 2007, and five terms as the Unite ...

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.https://leg.colorado.gov/sites/default/files/2023a_267_signed.pdf

References

External links

Tri-Lakes Projects
(Official site) - U.S. Army Corps of Engineers
Chatfield Lake Area Map
- Colorado Parks & Wildlife
Chatfield conditions and fishing reportsChatfield Storage Reallocation Project website
{{authority control Reservoirs in Colorado Bodies of water of Douglas County, Colorado Tourist attractions in Jefferson County, Colorado Protected areas of Jefferson County, Colorado United States Army Corps of Engineers dams Dams in Colorado Buildings and structures in Douglas County, Colorado Buildings and structures in Jefferson County, Colorado Dams completed in 1975