In a series of water court filings beginning in 1982, the Natural Energy Resources Company (NECO) owned by Dave Miller applied for water rights for components of the Union Park Reservoir Project. NECO sold the project to Arapahoe County. Arapahoe submitted a revised water rights application for the project in 1988. The project would have included an extensive diversion and water collection system in the headwaters of the Taylor and East River drainages, a 900,000 acre-foot reservoir located south of Taylor Park Reservoir in Union Park, and a system of tunnels and canals to convey up to 100,000 acre-feet of stored water annually to the South Platte basin. The Upper Gunnison District, among others, opposed the applications.

Following a five-week trial held in June 1991, the water court ruled that not more than 20,000 acre-feet of unappropriated water on an average annual basis was available for the Union Park Reservoir Project (1991 Water Court Decree). Arapahoe County determined that 20,000 acre-feet was insufficient to build an economically feasible project, and appealed the decision to the Colorado Supreme Court (1992 Appeal). On February 21, 1995 the Supreme Court remanded the case to the water court for an additional trial on water availability.

On April 6, 1998, based on new evidence presented during the second trial, the water court found that not more than 15,000 acre-feet of unappropriated water on an average annual basis is available to the Union Park Reservoir Project from the points of diversion claimed in the case (1998 Water Court Decree). Since Arapahoe County had previously acknowledged that 20,000 acre-feet of unappropriated water available on an average annual basis would be insufficient for its project, the water court dismissed the application with prejudice. Arapahoe again appealed to the Colorado Supreme Court. On November 20, 2000, the Supreme Court affirmed the water court’s judgment (1998 Appeal Ruling), ending Arapahoe County’s effort to divert water out of the Gunnison Basin. The District led the efforts of a number of opposers during extensive pre-trial preparation and motions, both trials and both appeals.