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Woman Creek Reservoir

Woman Creek ReservoirWoman Creek Reservoir is located northwest of Standley Lake, on the western edge of Westminster. More specifically, it is situated northeast of the intersection of 96th Avenue and Indiana Street, just west of the Stoney Creek Golf Course and south of Westminster Hills Open Space. The site is not recreational in use and is closed to public access.

Woman Creek is a shallow natural drainage originating in the area of the Rocky Flats National Wildlife Refuge. From the higher ground of Rocky Flats, it runs toward the southeast through rolling fields in the direction of Standley Lake. After crossing under Indiana Street, the creek is diverted into a channel that terminates at a concrete inlet structure on the northwest edge of Woman Creek Reservoir. An earthen dam wall almost fifty feet high marks the 29.9-acre reservoir’s perimeter. A graveled road and granite-covered embankments cap the dam wall. The surrounding prairie supports an abundance of wildlife, including prairie dogs, coyotes, fox, raptors and rattlesnakes. The mountains to the west act as a scenic backdrop.

The reservoir consists of three parallel basins, separated from one another by sloped embankments covered with granite riprap. Each basin is capable of holding approximately one hundred acre-feet of water. Under normal flow conditions, water entering the reservoir is diverted to the basins through valves and concrete culverts at the inlet structure. Floodwaters run over the top of the inlet structure and down into the central basin. The basin floors are finished with sand beds that act as filters.

The land where the reservoir sits was originally settled in 1891 when Ephraim Donaldson claimed it as a 160-acre homestead. Little is known about Donaldson other than that he was born in Pennsylvania around 1857 and by 1885 was farming in Jefferson County, Colorado. He does not appear to have resided in the state after 1900, and either died or moved away by that time. The farmstead on the northeast corner of Indiana Street and 96th Avenue was present by the late 1930s, and was apparently associated with agricultural activities on the site throughout the mid-20th century.

By 1990, planning was underway to deal with contaminated water flowing out of Rocky Flats toward the northern metropolitan area. Between 1952 and 1992, a massive industrial complex that manufactured plutonium triggers for nuclear weapons occupied the Rocky Flats area to the northwest of Woman Creek Reservoir. After the plant was decommissioned, it was re-designated the Rocky Flats Environmental Technology Site and the property became a federal cleanup priority. In 2001, Congress passed the Rocky Flats National Wildlife Refuge Act and much of the site was transferred from the Department of Energy to the National Wildlife Refuge System. Six years later the Environmental Protection Agency declared that cleanup efforts were complete and management of the property was placed with the US Fish and Wildlife Service.

Around 200,000 residents of Westminster, Thornton and Northglenn depended upon Standley Lake for their drinking water by 1990, and the communities were eager to protect the lake from contamination originating from Rocky Flats. In early 1995, the City of Westminster acquired the land for Woman Creek Reservoir from Jefferson County. The reservoir was constructed the following year as an integral part of the Standley Lake Protection Project.

The goal of the SLPP was to protect Standley Lake from contaminated stormwater runoff. This was accomplished by capturing all of the flow from Woman Creek, which drained approximately 35 percent of the Rocky Flats site. According to the Rocky Flats Cleanup Agreement, the Department of Energy remained responsible for testing water in Woman Creek where it crosses Indiana Street, prior to its arrival at Woman Creek Reservoir. This is known as the Indiana Street Point of Compliance, a critical stage in monitoring the quality of water flowing out of Rocky Flats.

Water entering Woman Creek Reservoir is held in each of its three basins for ninety days, treated if necessary, and then tested for quality before being released. From the reservoir, the water is pumped through a pipeline toward the northeast and into Walnut Creek below Great Western Reservoir. In this way, the water from Woman Creek is diverted around Standley Lake, isolating the drinking water supply from possible contamination. Fresh water is brought to Standley Lake from Coal Creek through the Kinnear Ditch Pipeline, replacing water that would normally have flowed into the lake by way of Woman Creek.

Originally owned and developed by the cities of Westminster, Northglenn and Thornton, in July 1996 an intergovernmental agreement transferred ownership, operation and maintenance of the reservoir to the Woman Creek Reservoir Authority. Funding for acquisition of the land and construction of the project was provided by a grant from the US Department of Energy. The reservoir was designed by CH2M Hill and installed by SEMA Construction.

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