FINDING OF NO SIGNIFICANT IMPACT CHERRY CREEK LAKE PROJECT 1991 MASTER PLAN UPDATE, D.M. CC-14 The Corps of Engineers proposes to approve an updated Master Plan for the Cherry Creek Lake Proj ect in the vicinity of Denver, Colorado. The Master Plan would accommodate moderate increases in visitation by allowing for upgrading of existing recreation facilities, and construction of new facilities principally near existing facilities and around the perimeter of the lake. An environmental assessment has been conducted and is incorporated by reference herein. The environmental assessment has been used to determine whether the action requires the preparation of an Environmental Impact statement. Negative effects identified for this action were deemed minor, including loss of some grassland and open space for new recreation facilities, and minor increase in displacement and disturbance of wildlife. No significant impacts were identified. Factors that were considered in making this decision included~but were not necessarily limited to} conservation, economics, esthetics, general environmental concerns, h·istoric values, fish and wildlife values, flood damage prevention, land use classification, navigation, recreation, water supply, water quality, energy needs, safety, food production, and in general the needs and welfare of the people. It is my finding that the proposed Federal action will not have a significant adverse effect on the environment and that the action will not constitute a major Federal action Significantly affecting the quality of the human environment. Therefore, an Environmental Impact statement will not be prepared. DATE: _2:_~_~~_'_"\_\ct_~_\ ~=B!~~Colonel, Corps of Engineers District Engineer ENVIRONMENTAL ASSESSMENT CHERRY CREEK LAKE MASTER PLAN OMAHA DISTRICT CORPS OF ENGINEERS MARCH 1991 ENVIRONMENTAL ASSESSMENT CHERRY CREEK LAKE MASTER PLAN THE PROPOSED PROJECT 1. Location. State: Colorado County: Arapahoe Reservoir: Cherry Creek Dam: Cherry Creek Nearest towns: Denver, suburbs 2. Problem and project Description. a. Problem. The existing Master Plan documents for Cherry Creek Reservoir Project are nearly 20 years old. They provide an inadequate basis on which to judge contemporary proposals. Soaring demand for recreation and non-recreation use at the project, and problems from the surrounding urbanization, have emphasized the need to update the Master plan to guide project development and use in the future. The special character of the project, derived from its natural undeveloped condition within the metropolitan setting, needs to be protected. b. project description. The proposed action is a revised Master Plan which accommodates existing recreation and provides for increased recreation, while preserving most of the project in undeveloped open space. The new Master Plan as proposed would add trail facilities, picnic shelters, handicapped fishing access, sprinkler systems, comfort stations, a playground, ranger buildings, shoreline erosion protection, utility lines, potable water, road paving, and other features, mostly at or adjacent to existing recreation areas, to upgrade and expand recreation resources. But it would concentrate activities near existing developments to minimize encroachment on the open spaces. And low density recreation would be the main objective of most of the project's open space. FUTURE AFFECTED ENVIRONMENT 1. General. The future affected environment will be the result of the impact of past, present and reasonably foreseeable future actions, without the proposed action. Prehistorically, project lands were short-grass prairie with deciduous woody growth in the drainageways. water was limited to the main stream channels. After human settlement, the project area was heavily used for agriculture. The city of Denver began growing up, and to provide flood control, Cherry Creek Dam was built upstream of downtown Denver about 40 years ago. Today, Cherry Creek project is surrounded by urbanization 1 and a growing population. It is a heavily used recreation area, managed intensively by the State and three municipalities. Many recreation facilities have been built inside the project and around its perimeter, and many recreationists visit the site each day especially during summer. However, the Cherry Creek project is also managed to protect wildlife, and it remains an iSland of habitat in the midst of the Denver metropolis. The future is expected to provide a continuation of some current trends. It is expected that population and recreation demand will continue to grow. urbanization will further isolate the project lands' wildlife, and will lead to further on-site erosion and pollution concerns. Under continuation of the current Master Plan, on-site natural resources would be somewhat preserved from urbanization by the presence of the Federal project. But also within the existing Master Plan, a variety of new recreation developments could occur, with more recreation facilities, more trails and more visitation. Demands for water for consumptive uses would also increase with the population. It is also possible in the future that major changes could occur, such as the addition of large volumes of water storage in the reservoir, but the likelihood of this is considered too uncertain to factor into this assessment. So the future environment at the project with past, present, and reasonably foreseeable actions would promise to retain a relatively undeveloped nature, but would be somewhat degraded by increased pressure from surrounding urbanization, increased recreation, increased facility development, and increased demands on the water. 2. Terrestrial Habitat and wildlife. Most of the project lands are upland habitat dominated by grasses such as wheatgrasses, forbs such as yucca, shrubs such as rabbitbrush, and occasional trees. Project lands around the pool include the dam face, sandy beaches, steep banks with scattered cottonwood trees, occasional shallow bays, and the delta complex. The delta complex is a large, diverse community which is growing and changing. The delta includes mudflats, low sandbars with willow shoots, wet depressions with cattails and reeds, and higher areas with willow thickets, trees, and tall grasses, lending much diversity to the habitat. On both the west and east sides of the lake, most of the shores are heavily used by the public. Many historically common species have been extirpated, but project lands remain a sort of refuge for some more tolerant or more to1erated species of wildlife. Habitat is more diverse than historically, because of the reservoir, the increased wetland areas, and manmade plantings. Management objectives of the state of Color~do's managing agency and the City of Aurora include 2 protection of the wildlife and its habitat. Hunting is not allowed. Terrestrial wildlife frequenting the area include mule deer, coyotes, jack rabbits, pheasants, Canada geese, marsh hawks, great blue herons, long tailed weasels, bullsnakes, and a sizable prairie dog population. Wildlife especially found in the delta include furbearers, some waterfowl, occasional bald eagles in winter, various shorebirds and waders, gulls, screech owls, diverse songbirds, bats, and some reptiles and amphibians. Wildlife which especiallY use the shoreline areas include raccoons, gulls, shorebirds and waders, blackbirds, and some reptiles and amphibians. Wildlife which use the spillway area include waterfowl, songbirds, raccoon, and deer. 3. waterfowl and shorebirds. Currently, little use is made of the project by ducks. Canada geese have begun to make increasing use of the project, and the State considers them overpopulated at the project. Great blue herons use the dead cottonWood trees at the delta end of the lake. A variety of shorebirds, waders and gulls make occasional use of the lake surface and shorelines during migration. 4. Fisheries and aquatics. Cherry Cree~ state Recreation Area is one of the most heavily used fisheries in the state of Colorado, especially for walleyes and trout. However, not all species are self-sustaining, because of the lack of good spawning habitat and the low dissolved oxygen levels. Viable catfish and panfish populations have developed. Walleye, muskie, trout and other species are stocked. Shad are self-sustaining and are the main forage for the sport fish. Minor spring fish kills of shad are common. 5. water Quality. The lake has a high nutrient content, a low dissolved oxygen content, and is eutrophic. urbanization has increased sediment inflows as well as contaminant inflows in recent years. Algal blooms can be a problem. Deposited sediments in the delta area are often resuspended by wave action and are redistributed in the lake. storm and flood events result in heavy run-off carrying large sediment loads which cause turbidity. Turbidity is considered a benefit in limiting algal blooms. 6. Threatened and Endangered species. The u.S. Fish and wildlife Service (FWS) was consulted, and advises that protected species in the area could include the black-footed ferret, bald eagle, and peregrine falcon. Bald eagles do visit the project for winter feeding and -roosting, possibly seeking waterfowl and prairie dogs. The eagles mostly use the dead cottonwood trees in standing water in the southeast portion of the project. They probably prefer these 3 for the isolation from shore and the visibility. This eagle winter use is very casual, unpredictable, and sporadic, not winter-long. Eagle presence in winter tends to coincide with low visitation levels, avoiding much