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The water year got off to a very slow start in Colorado. With winter storm tracks failing to favor us, snowpack and mountain precipitation were tracking well below normal throughout October and November. Winter finally arrived to Colorado in mid December and conditions steadily improved throughout the month. Unfortunately it was not quite enough, and as of January 1, snowpack readings remain below normal in all of the state’s major river basins. Due to the dry start to the water year, water supplies are currently expected to be below normal across the state this spring and summer. Adding to the water supply concerns, statewide reservoir storage is well below average as a result of last year’s poor snowpack and drought conditions. While it is still early in the season and anything can happen, water users should pay close attention to this winters weather patterns as well as the state’s snowpack and plan accordingly.
Dry conditions across Colorado during the fall and early winter season have resulted in below normal snowpack totals statewide. The storm systems that moved across the state in mid to late December greatly improved statewide totals; boosting the statewide snowpack from just 36 percent of normal on December 1 to 70 percent of normal on January 1. While this was a welcome change to the persisting dry weather patterns, as you can see, it was not nearly enough to bring statewide snowpack totals to near normal conditions. Current readings are only 91 percent of last year’s January 1 readings and this year’s January 1 snowpack replaced 2012 as the fourth lowest recorded in the last 32 years. The highest snowpack readings, as a percent of normal, are in the combined Yampa, White and North Platte basins. They recorded a snowpack at 85 percent of normal as of January 1. The lowest reading statewide is 61 percent of normal recorded in the Arkansas basin. In general, the Colorado, Gunnison and Yampa, White and North Platte basins have a slightly better snowpack than they had last year at this same time. The South Platte, Arkansas, Upper Rio Grande and combined southwest basins (San Juan, San Miguel, Animas, & Dolores) have received less snow this year compared to what they had accumulated last year on January 1. Given the current snowpack deficit, the state needs to receive above normal snowfall over the next few months in order to reach normal conditions by spring.
Precipitation in the mountains of Colorado was sparse during October, November, and the first part of December. Statewide monthly precipitation totals measured at SNOTEL sites were just 50 percent of average for October, and only 41 percent of average for November. The state finally received some moisture in mid December and total precipitation for the month of December ended up at 112 percent of average. Conditions were fairly consistent across the state during these months, with some variability during December. Monthly precipitation for December ranged from 99 percent of average in the Arkansas basin to 123 percent of average in the combined Yampa, White and North Platte basins. Year to date precipitation totals reflect the dry conditions in October and November. Statewide totals as of January 1 are just 68 percent of average. The combined San Miguel, Dolores, Animas, and San Juan basins have received the lowest precipitation, as a percent of average, at 59 percent of average. The Yampa, White and North Platte basins came in with the highest totals on January 1, as a percent of average, at 81 percent of average.
As a result of last year’s well below average runoff, Colorado’s statewide reservoir storage has been tracking below average since the end of May 2012. Storage volumes have dropped from 3,716,000 acre-feet at the end of May 2012 to 2,292,000 acre-feet reported at the end of December. Current storage volumes are only 68 percent of average and 65 percent of last year’s volumes at this same time. The lowest storage volumes, as a percent of average, are reported in the Upper Rio Grande basin, at just 50 percent of average. The only basins currently reporting average reservoir volumes for this time of year are the combined Yampa, White and North Platte basins. The Arkansas River basin is currently storing volumes at 56 percent of average. Reservoir storage throughout the remainder of the state is below average as well, with the remaining basins reporting between 66 to 77 percent of average.
The first seasonal streamflow forecasts of the season reflect the below normal precipitation and snow accumulation received so far this water year. Across the state, seasonal streamflow volumes are expected to be below normal. Forecasts for the streams in Colorado’s west slope basins range from just 47 percent of normal for Tomichi Creek at Gunnison, CO to 81 percent of normal flows expected for the Inflow to Willow Creek Reservoir in the headwaters of the Colorado River basin. Forecasts for the streams in the Arkansas and South Platte River basins are currently in the range of 50 to 70 percent of normal for the spring and summer season. The Upper Rio Grande basin currently has some of the lowest forecasts in the state; Sangre de Cristo Creek is expected to flow at just 36 percent of normal for the April to September period. And finally the basins in the southwest corner of the state are expected to see streamflow volumes ranging from 63 to 78 percent of normal this spring and summer.