The Colorado Supreme Court on Tuesday affirmed a water court's ruling over water rights being sought to serve about 50,000 people in Arapahoe County.

As part of a project with the East Cherry Creek Valley Water and Sanitation District, the United Water and Sanitation District had sought to acquire agricultural water rights held by Burlington Ditch Land and Reservoir Co. and the Farmers Reservoir and Irrigation Co. and change them to water rights for municipal uses.

The East Cherry Creek Valley Water and Sanitation District planned to use the water on the South Platte River so it wouldn't have to rely as much on groundwater as more people move in. Demand is currently around 9,000 acre-feet per year, but the district projects that will grow to around 14,000 acre-feet annually within 20 years, according to court documents.

On Tuesday, the Colorado Supreme Court agreed with a water court ruling that limited what could be considered the irrigation companies' historical consumptive use of their water, which helps determine how much water can be converted to municipal use. The water court had said it was trying to protect against harm to other water rights.