Colorado River Salmonfly Update – May 15, 2013
May 16th, 2013
This week’s big warming trend has started to make a push in early run-off. What we have seen over the past three days on the upper Colorado River has been a dramatic change to where we started the week. Of course this is all relative, as we were seeing things tracking below historic averages for this date. Now however, flows have risen to levels that are in line with where they should be. Today’s reading, as of noon, is right at 1,400 cfs and clarity is just about nil, with a generous measurement being 3 to 5 inches at Pumphouse and dropping as you move down river.
We were seeing some good progression with the Pteronarcys nymphs in their migration towards the bank, along with a steady rise in water temperatures getting close to that 59-60 degree mark that initiates the hatch. At the warming rate of almost one degree a day early this week, there was the possibility for an emergence by as early as this weekend. However, with this spike in water we now are anticipating a push back in that emergence. Not only have water temperatures dropped from a Tuesday high of 57.5 back down to 56 yesterday, with an anticipated high today maybe only as warm as 53 degrees but, with that much added water, the nymph migration from the river channel to dry land on which to hatch is a little farther to crawl.
All of that being said, it now looks as if the hatch will probably come somewhere closer to a normal year emergence period. That being somewhere around the last week of May. Ultimately, lot of things can have an impact on when and even if the hatch materializes. If the flow stabilizes and once again starts to warm, then we will once again be in positive movement. If water levels continue to rise, then temperatures may take a bit longer to once again move upward, thus stalling the hatch some more.
Our plan at this time of year is to be on that water daily in order to monitor this hatch. If it happens it is short lived and not to be missed so, we will do our best to keep this information current. Don’t hesitate to call for more insight into conditions.