Thursday, May 2, 2013

Arkansas River Runoff Prediction 2013


 
         Curiosity is running rampant as we all want to know what type of runoff the Arkansas River has in store for us.   Unfortunately predicting the exact extent of the water to come is a difficult task which is impossible to determine down to a strict certainty.  Many factors play a role in how high flows will reach and the duration at which they will hold.  This year is particularly difficult to gauge thanks to the relatively severe drought of last year and the influx of our current spring storms. 

As this season opened the slow start of snow accumulation caused drastic measures to be discussed across the state.  Colorado Springs went on mandatory water restrictions and a plan was set for the draining of Antero Reservoir.   As late March and early April set in however so did the spring storms.  These storms vastly improved the drought situation, but to what extent are still undetermined.  Snowpack is measured in snow water equivalent inches and there are two ways of considering percentages of snowpack.  The first is to look at the total snowfall over the season (Oct. through May) and the other is to observe the current available snowpack.  Last year we received 77% of average total average, but received much of that total early and much of it had melted off by early spring.  This year we have reached 78% of the average for the total snowpack.  So in relation this year is not much different from last year in total water.  The huge difference however between last year and this year is that we currently have a snowpack on ground that is 324% higher than last year.  It is this number which leads us to believe that a true runoff will occur this year.
The upper Arkansas, above Canon City, and the local tailwater will experience runoff differently.  The upper river is subject to the weather.  If several consecutive days of warm weather occur a more dramatic runoff will be seen. If things continue as they have however with cold days breaking up our warm spells then runoff will be gradual and slow.   Regardless of how it happens there is a sense of predictability to the runoff on the upper Ark.  The water will rise to its unknown peak and then will come back down to a relatively stable flow.  Below Pueblo Dam however is a much different story.

  Pueblo Tailwater is controlled only in part by mother nature. It is true that if the reservoir has reached a capacity that does not required any further storage the powers that be may mimic "in-flows" with "out-flows."  Due to last years drought however this is very unlikely to occur.  The current lowered levels of the reservoir will limit how high the release from the dam will be, as any excess will be retained as storage for the reservoir.  The timing and extent of the release from the dam will be dictated more by the needs of the water rights holders to the east.  Many of the sudden increases of water seen in the summer months will be a direct result of the water rights holders placing calls for water downstream. There is no forewarning when these calls will come and therefore the river can change dramatically from day to day.  The encouraging part of this litany of information is that there ought to be enough water available to constitute releases which will be conducive to maintaining our fishes through the hot summer months.  Higher water will present a new set of challenges as fish spread out and have a larger selection of foods flushed from the reservoir, but these are good issues and ones we welcome.  The health of the fish is vital to us and if that means fishing in higher water, bring it!

All source data about snowpack levels was obtained through the NRCS (Natural Resources Conservation Service) and can be viewed at :



               

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