Mower Reservoir is located northwest of Standley Lake in the 1,029-acre Westminster Hills Open Space, west of the intersection of 100th Avenue and Alkire Street. The city’s open space and forestry facility is located just east of the reservoir at 10001 Alkire Street. Pedestrians access the reservoir along the Westminster Hills Trail from a parking lot on the west side of Simms Street at 105th Drive. The 11-acre lake, only about five feet deep, is bordered by cottonwood and willow trees, and surrounded by rolling open prairie that serves as home to wildlife that includes prairie dogs, coyotes, fox, raptors and rattlesnakes. A panoramic view of the mountains to the west acts as a scenic backdrop to the entire site.
A low earthen dam wall retains the reservoir along its eastern shore. Running along the top of the wall is a graveled path lined by trees. A narrow unimproved path continues around the lake’s perimeter and provides access to a small wooden pier located on the southwest shore. At the reservoir’s southeast corner is a concrete spillway that drains into an outflow channel that heads toward the southeast in the direction of Standley Lake.
While today the lake depends entirely upon stormwater runoff, Mower Reservoir was originally fed with surface water drained from Rocky Flats and diverted from Woman Creek. The headgate for the Mower Ditch is located on the north side of Woman Creek three-quarters of a mile west of the reservoir. From this point, the earthen ditch travels east through the open prairie, reaching the reservoir along its northwest shore.
Samuel A. Mower constructed the reservoir and ditch after filing for a 160-acre homestead patent on area farmland in 1891. Born in Pennsylvania in 1853, Samuel was the son of farmers Simon and Catherine Mower. By the summer of 1880, he had moved west and was working as a farmhand in Jefferson County, Colorado. In 1885, Simon married a woman from Illinois named Frances and before long they had a daughter they named Alice. By 1900, the Mowers had four more children and were farming in the countryside northwest of the town of Westminster, below an area known as Rocky Flats. Samuel and Francis moved to Los Angeles prior to 1910, and over the following years moved up the coast to Oakland. In 1920, Samuel was employed there as an elevator operator at a newspaper company. He died in Oakland the following year.
Mower Reservoir and its associated ditch were used for decades to provide irrigation water for area farmland. However, flow through the ditch was curtailed in recent decades as efforts were instituted to protect the quality of water in Standley Lake by controlling upstream flow from Rocky Flats. The City of Westminster annexed the reservoir in 1997 and since then improved the dam wall and spillway.