Dillon Reservoir has dropped more than 20 feet since spring, and Denver Water expects it to fall another 8 to 10 feet by Labor Day. That's the backdrop for a decision in front of Denver Water's board this month: making October 1 a mandatory shutoff date for lawn sprinklers, not just the informal end-of-season guidance it's been in past years.
If you're used to letting your system run on autopilot into October, this is the year that habit could actually cost you.
What's being proposed
Denver Water is considering formalizing the end of the outdoor watering season on October 1, 2026. If the board approves it, automatic and spray irrigation systems have to be shut down by September 30, and after that, hand-watering trees is the only outdoor watering allowed. Greg Fisher, Denver Water's manager of demand planning, put the stakes plainly: “Our reservoirs are projected to be only 60% full next spring — every drop saved goes a long way.” Until the vote, the current rules still apply: two assigned watering days a week based on your address, no watering between 10 a.m. and 6 p.m., and no letting water pool on sidewalks or driveways.
Why this year is different
Denver Water declared a Stage 1 drought back in March, aiming for a 20% cut in water use citywide. As of this summer, actual usage was down only about 5% — nowhere close to the goal. Meanwhile, the snowpack that feeds the system peaked at historic lows this spring: the South Platte River Basin hit 42% of normal, the lowest on record, and the Colorado River Basin came in at 58%. Reservoirs system-wide are sitting at 73% capacity, well below the typical 95% for mid-August. Antero Reservoir is completely dry. Williams Fork is down to a third full, with hydropower generation there set to stop for the season. Nathan Elder, Denver Water's water supply manager, summed it up: “This year we are making significant withdrawals from our savings — and we don't know how long the hot and dry weather conditions will last.”
The numbers explain why sprinklers specifically are the target. In July, Denver Water customers used an average of 282 million gallons a day, compared to roughly 110 million gallons a day in the winter months when nobody's watering a lawn. More than half of what gets used all summer is going straight onto grass.
What to do before the deadline hits
Whether or not the board makes it official, treat September 30 as your real deadline this year, not October 1. A few things worth doing now instead of later:
- Book your sprinkler blowout early. Once nighttime lows start dropping toward freezing, usually sometime in October, that's the signal to winterize. Companies book up fast that week, and waiting until a hard freeze catches you off guard can mean cracked pipes and a much bigger bill.
- Keep fixing leaks within 10 days. That rule isn't going away, and it's an easy one to get dinged on if a sprinkler head's been quietly running for weeks.
- Start thinking about next spring now. If your system is old or your landscaping is thirsty by design, this is a good winter to plan a change rather than start the same conversation over in May.
What this means if you're buying, selling, or just staying put
I'm already having more conversations with buyers about water-wise landscaping than I was a few years ago, and this is exactly why. A yard that leans on drought-tolerant plants and efficient irrigation isn't just good for a water bill — with restrictions tightening like this, it's turning into a real selling point in neighborhoods like Park Hill, Congress Park, and Central Park. If you're weighing whether a landscaping refresh is worth it before you list, or want to know what buyers are actually asking about these days, I'm happy to talk it through.
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