Snowpack down, stream runoff will be low if things don't change
The March 1 snow and runoff report is in from the state, and the spring and summer season for water looks a little bleak for this year.
Snowpacks are below to much below average over Utah. Snowmelt runoff conditions are poor and not likely to improve significantly over the next month. There is only one month remaining in the snow accumulation season and the accumulation necessary in March to get to average ranges between 200 percent on the Bear to over 400 percent for southwest Utah. Most areas need a 250% of average accumulation to reach average by April 1. This is not likely to happen.
What is more likely is that the state will see 70 to 80 percent of normal snowpacks this year. February precipitation was much below (68 percent on the Weber) to near average (103 percent on the Uintahs).
Central Utah to the Duchesne was near average with the southwest and north below average which brings the year to date precipitation to a below average 84 percent.
Current soil moisture saturation levels in runoff producing areas are: Bear River 50 percent, Weber 51 percent, Provo 35 percent, Uintah Basin 41 percent, Southeastern Utah 39 percent, Sevier 44 percent and Southwestern Utah 41 percent of saturation. Northern Utah soils are dry and southern Utah soils are near average. All are much less than last year.
Low snowpacks and low soil moisture lead to poor runoff. Reservoir storage is currently at 87 percent of capacity statewide which is 17 percent more than last year at this time.That is due to runoff from a heavy winter in 2010-11.
General water supply conditions (expected runoff plus reservoir storage) are near average across the state due to good reservoir storage.
Actual streamflow forecasts range from 41percent on Vernon Creek to 89 percent on the Whiterocks River near Whiterocks in Uintah County. Surface water supply indices range from 37 percent on Ferron Creek to 75 pecent for the lower Sevier River.
March 1st snowpacks as measured by the NRCS SNOTEL system are as follows. Bear - 77 percent, Weber 69 percent, Provo 64 percent, Uintahs 78 percent, Southeast Utah 62 percent, Sevier 71 percent, Southwest Utah 77 percent and the statewide figure is 72 percent of average.
With only March remaining in the snow accumulation season, the range of potential snowpack outcomes is fairly small depending on future climatic conditions. If drought and early melt prevail, snowpacks could range between 15 percent (SW Utah) and 50 percent (Bear) of average. Given maximum accumulations, April 1 snowpacks could range between 90 percent (Weber) and 125 percent (SW Utah) of average.
Getting back to average April 1 at this point requires maximum and above accumulation in March. With normal accumulations, April 1 snowpacks will be between 70 percent and 80 percent of average snowpack statewide.
Mountain precipitation during February was: Bear 83 percent, Weber 68 percent, Provo 81 percent, Uintahs 103 percent, Southeastern Utah 91 percent, Sevier 100 percent, Southwestern Utah 77 percent and the statewide figure is 86 percent of average. This brings the seasonal accumulation (Oct-Feb) to 84 percent of average statewide.
Storage in 41 of Utah's key irrigation reservoirs is at 87 percent of capacity, 17 percent more than last year. Reservoir storage by Basin is the Bear 77 percent, Weber 82 percent, Provo 93 percent, Uintah Basin 88 percent, Southeastern Utah 78 percent, Sevier 93 percent, and Southwestern Utah 82 percent of capacity.
Snowmelt streamflows are expected to be below to much below average across the state this year. Forecast streamflows range from 41 percent on Vernon Creek to 89 percent on the Whiterocks River. Most flows are forecast to be in the 50 to 80 percent range.
Snowpacks in the southeastern region are much below normal at 62 percent of average which is about 51 percent of last year.
The percent of average snowpack for individual sites range from 35 percent at Fish Lake to 100 percent at Donkey Reservoir SNOTEL stations.
The precipitation during February was near average at 91 percent, bringing the seasonal accumulation (Oct-Feb) to 87 percent of normal.
Soil moisture estimates in runoff producing areas are at 39 percent of saturation in the upper 2 feet of soil, compared to 64 percent last year at this time. Forecast streamflows (April-July) range from 48 percent to 79 percent of average.
Reservoir storage is at 78 percent of capacity, 23 percent higher than last year at this time. Surface Water Supply Indices for the area are Price 62 percent, Joe's Valley 40 percent, Ferron Creek 37 percent, and Moab 62 percent. General runoff and water supply conditions are near average in the Joe's Valley area, below average in the Ferron Creek area, and above average in the Price and Moab areas due to reservoir storage.