A years-in-the-making experiment to catch neighborhood rain in Douglas County is now officially under a judge’s microscope in Colorado water court. Dominion Water & Sanitation District is seeking permission to operate a regional rainwater-harvesting basin at Sterling Ranch, to legally capture roughly 111 acre-feet of water annually for nonpotable uses, such as irrigating parks. In Denver, researchers are conducting rooftop tests to determine how much rain can be safely put to work. If the court signs off, Sterling Ranch, the state’s lone pilot site, would move from data collection to real-world water deliveries, and the ruling could help decide whether other Colorado developments even try to follow suit.
On a test rooftop at CSU Spur in Denver, Colorado State University professor Sybil Sharvelle said the system has so far not had to use potable water to supplement the irrigation, she told CBS Colorado. Britta Strother, director of planning for Dominion Water & Sanitation District, told the same outlet that Dominion has spent years studying Sterling Gulch’s rainfall, runoff, and soil infiltration and that the community sits “right above what will be Colorado’s very first rainwater harvesting basin.”
What Dominion is asking for
Dominion’s water-court filing seeks authorization to harvest “approximately 111 acre-feet of water annually,” the pilot’s project manager told CBS Colorado. Dominion’s own grant and feasibility documents show the full Sterling Ranch program could produce up to roughly 400 acre-feet a year at full buildout, though the first capture sites would be much smaller and constructed in phases, as outlined in a Dominion Water & Sanitation District grant application.
How the system would work
The plan relies on diversion structures, a physical berm across Sterling Gulch, and a series of small storage basins to grab runoff that currently sheets off roofs and paved surfaces, then pump that nonpotable water back into neighborhood parks and landscaping. Pilot monitoring and regional accounting tools used to calculate how much water can be taken are designed to show that the harvest captures only increased runoff from development, not the historic flows that downstream users already rely on, according to Water Education Colorado.
Legal hurdles and the policy clock
Even if the engineering pencils out, Colorado law keeps the bar high. Projects must prove they will not injure downstream water rights holders by using augmentation plans and meticulous accounting, a process handled in water court and described in state guidance and legislative reports. The Division of Water Resources also notes that the statute authorizing these pilot projects (Section 37-60-115(6), C.R.S.) is scheduled for repeal on July 1, 2026, a timing crunch that could limit new applicants unless lawmakers extend the program, according to the Division of Water Resources and a June 2025 report to the General Assembly.
Why other communities are watching
Interest around the state is high, but actual participation has been almost nonexistent. Sterling Ranch is still the only community to win approval as a pilot, and reporters say the time, expense, and legal complexity have helped scare off smaller water providers, as documented by Water Education Colorado. That scarcity makes the pending water-court decision especially consequential: a green light could encourage more pilots, while a rejection or the statutory sunset could effectively stall commercial-scale rainwater harvesting in Colorado.
Dominion has said it would file in water court, and Andrea Cole told The Colorado Sun that, because of likely opposition, she expects the legal review could take “up to three years.” For residents, the case will test whether raindrops, long treated as part of Colorado’s downstream water system, can instead serve as a local, renewable supply for parks and open space.
