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 5 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.
History of Mower Reservoir
The origins of Mower Reservoir date back to the early 1870s settlement of the area below Rocky Flats, when Colorado was still a territory of the United States. According to an 1885 plat that was filed with Jefferson County by Samuel Mower, in 1872 an earlier owner whose identity was not revealed constructed the reservoir and the ditch that feeds it with water. These had been in continuous use through the mid-1880s, when Mower filed his plat for the Mower Ditch and Reservoir, and they have been known as such ever since.
Samuel A. Mower was born in Pennsylvania in 1853, and 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. Samuel married a woman from Illinois named Frances in 1884, and before the year was out, they had a daughter named Alice. The young family homesteaded around that same time on the open treeless land below Rocky Flats. They acquired an existing irrigation ditch and reservoir with their 160-acre property, which was situated directly east and southeast of the reservoir. Samuel received the patent to the land in October 1891 from the United States government. By 1900, the Mowers had four more children and were still farming their irrigated crop fields in the countryside northwest of the town of Westminster.
Sometime prior to 1910, Samuel and Frances moved to Los Angeles, Calif. with their three youngest children, having turned away from farming on the high Colorado plains. Within a few years they relocated again, this time up the coast to Oakland, Calif. Samuel was employed there around 1920 as an elevator operator at a newspaper company. He died in Oakland the following year and is presumably buried in a Bay Area cemetery.
After the Mowers headed west to California, Mower Reservoir continued to provide the privately-owned agricultural lands to the southeast with irrigation water well into the 20th century. Flow through the ditch and into the reservoir was curtailed in recent decades as regional changes were instituted to protect water quality in Standley Lake by controlling upstream flow from Rocky Flats. The City of Westminster acquired and annexed the reservoir in the mid-1990s, and has since then improved the dam wall and spillway. Today the reservoir is no longer supplied by the ditch and depends entirely upon stormwater runoff.
Prepared by Ron Sladek, Tatanka Historical Associates Inc.