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Cheesman Canyon Update

For the first time in many years, Cheesman Reservoir is back on track to reach full pool during the first part of May.  Denver Water confirmed that they will let the reservoir “fill and spill” this year. Late last week, Denver Water ramped up the outflows to slow down the spill and make sure there was adequate water coming off the bottom of the reservoir to keep the water temperatures in check.

Cheesman Reservoir is currently 525-acre feet (99 percent capacity) from full pool. Denver Water expects the lake to spill in the next few days. Everything is subject to change, however. This all depends on downstream demand, cold snaps, warm weather trends, and rain; but things look really promising!

Denver Water was kind enough to shed some light on future flows in May, June, and July. They plan to keep a close eye on water temperatures and make any necessary adjustments to keep the trout happy.  There are three release points on Cheesman Dam: bottom valves, jet valve (60 feet below full pool), and the spillway. Each release point has a profound effect on the water temperatures in the mileage below the dam.

Denver Water is forecasting that the average flow in May will be around 400 cfs, then it should ramp up as the snowfields begin to melt. The good news is that all the reservoirs in the South Platte corridor are full, so the “melt” should pass through the watershed quickly providing a much-needed flush in Cheesman Canyon.

In June, Denver Water believes outflows could reach upwards of 750 cfs (possibly higher), peaking in the middle of the month, then tapering off as the snow on the Mosquito Range and Weston Pass disappears. This is exactly what the “canyon’s” substrate needs after last year’s devasting flash flood on July 31, 2023. Only time will tell, but it appears that we are heading in the right direction to begin the recovery process.

Denver Water plans to take the outflows off the spillway by July to keep the river temperatures cool, especially in the lower stretches below Deckers.  Hats off to Denver Water for providing this helpful information and protecting the resource for our finned friends.

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  1. Chris J Hanson on May 7, 2024 at 8:03 am

    Thanks for the super informative update Pat. Sounds very promising for this special place.

  2. David Goff on May 7, 2024 at 9:24 am

    Thanks for the update Pat. Hope your “office” gets the cleaning it needs.

  3. Don on May 7, 2024 at 9:49 am

    Pat at 360 is the river still fish able? I have a friend coming in Thursday. Thanks for the help.

    • Pat Dorsey on May 7, 2024 at 10:29 am

      Absolutely, it’s fishing great with those flows. Fish a San Juan wormed trailed by caddis larva, pupae, or Baetis nymphs!

  4. Scott Tampa on May 7, 2024 at 9:50 am

    Pat, thanks for sharing this potentially great news! Hopefully the canyon gets back to unclogged pools in the near future.

  5. Dan on May 7, 2024 at 7:06 pm

    Pat, really appreciate getting the inside-scoop! Thanks for sharing this. Great news

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Pat Dorsey Fly Fishing