It’s the time of the year when irrigators and water suppliers keep one eye on the sky, hoping for a copious snowpack everywhere across the state, so that conversation can center on how much water Colorado bypassed to other states rather than on allocating a short supply.
The January 1, 2012 Basin Outlook Report from the Natural Resources Conservation Service was made available for download today and many water wonks are not going to like what they see. Remember, the NRCS maintains that they can forecast runoff to within 10% based on the data they collect from selected snow courses around the high country so many rely on the forecast for planning purposes. It’s going to be a dry year, so far.
Click on the thumbnail graphic for the streamflow forecast map.
Here’s an excerpt from the report:
The water year got off to a good start with October posting 136 percent of average precipitation. Since the end of October, statewide year-to-date precipitation has fallen to 86 percent of average. January 1 snowpack totals for Colorado are also below average at 71 percent of average. This year the southern basins in Colorado have received more frequent storms than the rest of the state resulting in near average snowpack conditions in those basins. Reservoir storage remains in good condition across most of the state. The combined average for Colorado reservoir storage is 105 percent of average as of January 1. Early season runoff forecasts call for below average runoff for most of the state with the streamflow in the southern basins projected to be nearer to average. This month’s Water Supply Outlook Report is compiled using precipitation and snowpack data provided by SNOTEL sites only. With a little luck, the jet stream will shift and provide a more favorable storm track for the rest of the season.
Snowpack totals are below average in all major river basins in Colorado as of January 1. Statewide, snowfall has been below average each month since the start of the water year. While precipitation during the month of October was well above average, temperatures were too warm to allow that precipitation to be stored in the snowpack. In late November, concerns about lack of snowpack across Colorado increased as most of the storms tracked either north or south of the state. In general the jet stream has tracked to the north of the state which has allowed the weather to be dominated by high pressure. As of January 1 the snowpack was measured at 71 percent of average which is 52 percent of the snowpack measured this time last year. With 60 percent of the winter snowpack accumulation season remaining a lot can still happen. The state needs above average snowfall for the next three to four months to return conditions to normal before spring and summer runoff begins.
Precipitation across Colorado’s high county was well above average for the first month of the 2012 water year. Statewide total precipitation during October was 136 percent of average. November was a somewhat drier month across with 80 percent of average precipitation reported at SNOTEL sites across the state. Total precipitation amounts for the month of December were considerably lower than the previous months at just 52 percent of average. Only the Upper Rio Grande basin reported above average precipitation for December with totals at 101 percent of average. Northern basins reported notably below average precipitation for the month of December. The Yampa, White and North Platte basins received only 28 percent of their monthly precipitation average in December, and the Colorado River basin recorded just 32 percent of its average December precipitation. Despite December precipitation measuring well below average statewide, the above and near average precipitation totals during the previous two months has somewhat compensated; leaving year-to-date precipitation for Colorado at 86 percent of average. The Yampa, White and North Platte basins recorded 75 percent of average year-to-date precipitation as of January 1 and the Colorado basin was at 72 percent of the year-to-date average. The Arkansas, Upper Rio Grande, combined San Miguel, Dolores, Animas and San Juan basins all report year-to-date precipitation totals equal to or slightly above average as of January 1.
Reservoir storage across Colorado continues to track near the mid-winter average. Statewide storage on January 1 was 105 percent of average and was 105 percent of last year’s storage volumes reported at this same time. Broken down by basin the Colorado, South Platte and combined Yampa, White and North Platte basins all reported above average reservoir storage on January 1. Likely a lingering effect of the above average streamflow volumes recorded in those basins last spring and summer. The Gunnison, Arkansas and combined San Juan, Animas, Dolores, and San Miguel basins all reported near or slightly above average storage for January 1. The only basin in the state reporting below average reservoir storage is the Rio Grande which was at 64 percent of average on January 1.
At this point in the water year streamflow volumes are forecast to be below average statewide. The only forecasts issued that predict average or above average conditions for this spring and summer are located in the Arkansas River basin. Forecasts for the Purgatoire and Huerfano Rivers located in the lower portion of the Arkansas basin were at 106 and 100 percent of average respectively as of January 1. April to September runoff forecasts for streams located in the Upper Rio Grande basin range from 73 percent to 99 percent of average. The forecasts for the Colorado, Gunnison, Yampa, White, and North Platte and the San Miguel, Dolores, Animas, and San Juan basins are all in the 60 to 85 percent of average range. The South Platte basin faired a little better with April to July forecasts ranging from 68 percent of average for Bear Creek at Morrison to 95 percent of average for the Inflow to Antero Reservoir. At this point above average snowfall is needed for the remaining winter months to improve runoff conditions for the state this spring and summer.