Gray Reef Flushing Flows Explained

Like clock work, every spring, Gray Reef sees a 7-10 day increase in flows.  A collaboration of efforts by Wyoming Game and Fish, University of Wyoming, Wyoming Fly Casters and the Bureau of Reclamation-this increase in flow plays a vital role in the self sustaining Grey Reef trout population.  That being said, there always seems to be a degree of lingering questions in regards to the “flush”.  Here’s a brief article explaining the how, why, and what of the Grey Reef flush.

It was 1987 when a gas spill more or less wiped out the trout population below Gray Reef reservoir.  This combined with several low water years and increasing sediment made for a rapidly declining population.  With this increased sediment biologists saw a loss of spawning habitat and a documented shift in aquatic invertebrate communities.  Not good for the trout of Gray Reef.  In 1992, a study to evaluate the benefits of flushing flows was conceived and in the fall of 1995 the flush was born.

Now to spare everyone a fair bit of scientific jargon, we’ll just give you the straight facts.  While the impacts of the initial flush were positive, they were by no means a one and done kind of fix.  The Wyoming Game and Fish Department knew that these types of flows would have to continue, hence they began requesting to the Bureau of Reclamation to provide a cycle of spring and fall flushing flows.  Spring flushing flows have been annually slated for March, as soon as the ice is off and prior to the beginning of the rainbow spawn.  Fall, on the other handed, was recommended but has been ultimately canned due the problems with the vegetation and water intake facilities (i.e. Dave Johnson Power Plant below Casper).

In a perfect world fall flushing flows would be ideal, especially for those of us that witnessed the streamer bonanza that was the fall flush…which I believe the last one was in ’08 or maybe it was ’09.  It was honestly, truly, some of the best streamer fishing we’ve ever seen!!  Well, can’t dwell in the past and there are several postives to NO fall flush.  The “dreaded” vegetation of the late summer/early fall provides cover for the young trout, other fish and many invertebrates that call the river home.  It really is great habitat.  And with the vegetation slowing decaying throughout the late fall and winter months, the precious nutrients remain in the upper reaches of Gray Reef.  Good for the river, good for the fish!

We can probably all agree with the positive impacts seen from having consistent flushing flows.  Better habitat=more bugs=bigger, better, healthier fish=wild fish population.   So, to those that helped in the implementation of the flushing flows and its continuance, we thank you!