Blue River Below Dillon Reservoir Release Plan From Denver Water
The Blue River here in Silverthorne continues to run at a rather robust level. As of this morning, current flows are 792 cfs. This is after the second step back up in releases this week after a short lived recession down to 525 cfs. Not only has the release gone up, it will continue to rise over the week, maybe even as high as 1200 cfs.
This looks like a situation that will continue for some time as was laid out in an email from Denver Water Public Affairs person Dana Strongin yesterday :
“Dillon Reservoir’s outflow, which this morning was about 630 cubic feet per second (cfs), is ramping up to about 750 to 800 cfs this afternoon. Denver Water expects to continue making increases throughout the week to end at an outflow between about 950 to 1,200 cfs, depending on conditions.
We have been focusing this season on trying to balance Dillon Reservoir’s inflows with its outflow to the Blue River to help avoid flooding. We also do not want to spill the reservoir this year because of a maintenance project on Dillon Dam’s outlet works, during which we’ll be using a temporary siphon system to continue releases into the Blue River. Construction on the siphon system is set to begin Monday, July 7. (More information about this project will be available on our website, www.denverwater.org, in the next day or two.)
Denver Water will set Dillon’s outflow rates for the next few weeks based on the need to keep the reservoir’s elevation – which today is about a foot from full – relatively steady. Inflows are coming in today at about 1,200 to 1,300 cfs and are expected to slowly decrease over the next several days.”
With that in mind, it looks as not only will flows in town continue to run high but, they will be bottom release. Which has implications on a couple of levels. First, with the tailwater release we anticipate a continuation of Mysis Shrimp pouring into the river, providing a steady source of food for trout as well as an easy starting point for angler fly selection. Second, the tailwater release will be much colder water than if the reservoir were allowed to “fill and spill”. This will have an impact on summer insect hatches. At this point it is hard to conclusively predict exactly what will happen but, we will probably see reduced numbers of PMDs here in town. Further downstream the river will warm as it absorbs solar radiation and the chance for seasonal hatches should be better.
As for the fishing here in town, we anticipate things will continue as they have for the past two months, which has been very good. The high water will limit wade accessibility, but concentrate your efforts on the quiet water along the edges where fish will seek refuge from the main channel. It will be necessary to bump up your weight for a quick descent in those tight pockets, somewhere in the neighbor hood of 4 BB or even 2 AAA. You can also bump up your tippet size with the heavier flow, to 3X as it gets up to 1,000. Along with your favorite Mysis patterns, San Juan Worms, Egg Patterns, various Mayfly nymphs and even some dead drifted streamer patterns have all been productive.