Lawn Irrigation Return Flow Monitoring Wells

Where does the water we pour on our lawns go?

Good water supply management means looking at all options to obtain supplies for our growing Town. The most cost-effective solution for additional water supplies are those already located within the Town. The most sustainable supplies are renewable surface water rights such as those owned by the Town on Plum Creek and East Cherry Creek. These creeks are considered renewable supplies because water is continually flowing into the creeks from precipitation and stormwater runoff. However, there is an emerging and growing source of supply for these creeks that positively impact our water rights: Lawn Irrigation Return Flows.

Castle Rock residents pour about half of all the water used in Town on irrigation. Of that lawn irrigation water, some seeps into the ground and nourishes plants, some evaporates, and the rest travels underground back into to the creeks. In fact, throughout the Front Range, Lawn Irrigation Return Flows have actually resulted in perennial streams in historically dry channels! Figuring out how much water from lawn irrigation returns to the creek and how long that journey takes will help us fully and efficiently use our existing water rights, and is the reason for the Lawn Irrigation Return Flow monitoring well project. Castle Rock Water expects this renewable water source could provide five percent of our total water supply, expanding our diverse water supply portfolio.

Project scope

In 2021 Castle Rock Water completed drilling 26 shallow monitoring wells throughout Town. These 50- to 120-foot-deep wells are located in open spaces, usually within a utility easement. The wells monitor and quantify the water seeping underground and traveling to the creek. In 2023, five additional shallow monitoring wells will be drilled. The drilling will take one to two days for each well.

Construction will take place Monday to Friday, 7 a.m. to 7 p.m. and Saturday, 8 a.m. to 6 p.m. No overnight drilling is needed. Residents can expect some traffic lane closures. However, there will be no water service disruption. The well head will usually be flush mounted with the ground and the surrounding property will be re-vegetated. Upon completion, staff will access the monitoring equipment periodically.

Project update

Castle Rock Water is in the process of obtaining a contractor to complete the remaining five monitoring wells. The existing 26 wells are now collecting data and staff will periodically access the sites to check equipment and manually collect data.

Well locations

• Cobblestone  
• Crystal Valley Ranch  
• Founders  
• Meadows  
• Metzler Ballpark  
• Plum Creek Golf Course  
• Red Hawk  
• Sapphire Pointe 
• Terrain at Autumn Sage