Opinion by Lee Hackleman
NRCS Provides Wyoming Snow Survey and Water Supply Forecast Program
By Lee Hackleman, NRCS Water Supply Specialist
Welcome to the start of the WY-12 Water Supply Forecast Season. With more than a third of the snow accumulation season behind us for the Northern Tier States, and more than half gone for the Southwest, things are looking quite grim so far for most of the Western states. By grim, I mean I think we will have a slightly below average snowpack this year. The reservoir storage is good, though, so we should be all right this year.
We started the 2011-2012 water year on Nov. 1, 2011 with our first Monday Morning Report. We were at 68 percent of average (1970-2000) for the state. The Powder-Tongue (PT) River Basins were high at 107 percent, the Belle Fourche (BF) drainages were low at 20 percent and the Wind River (WR) Basin was at 47 percent of average.
On Nov. 21, 2011 we were up to 110 percent and looking good, like a normal La Nina year. The PT was at 141 percent, the BF went to 109 percent and the WR was up to 87 percent.
We dropped continually all December (Dec. 27, 2011) to 80 percent of average for the state. The PT was at 113 percent, the BF was at 84 percent and the WR was at 78 percent.
Our latest monthly report on Jan. 9, 2012 shows us up to 80 percent of average for the state. The PT was at 113 percent, the BF was at 81 percent and the WR was at 78 percent.
The Cooperative Snow Survey Program
Since 1935 the Natural Resources Conservation Service (NRCS) Snow Survey and Water Supply Forecasting Program has monitored mountain snowpack and climate variables in the Western United States to forecast spring and summer water supply.
The earliest snow measuring sites in Wyoming date back to the 1920s. In the late 1970s, NRCS began installing automated SNOTEL (SNOwTELemetry) monitoring stations throughout the West. Today, Wyoming NRCS coordinates the Federal-State Cooperative Snow Survey Program, which includes 64 manually sampled snow courses and 90 SNOTEL stations in Wyoming (which includes two we administer in South Dakota).
West wide, there are 1,200 manually sampled sites and 730 SNOTEL stations. This network provides the snowpack and climate data required to forecast spring and summer water supplies that affect Wyoming water users. A wide variety of economic decisions, totaling many millions of dollars annually, are dependent on the snowpack data collected and water supply forecasts issued by the NRCS.
The SNOTEL Data
Collection System
The key to determining spring runoff is the timely and accurate monitoring of remote mountain snowpacks. SNOTEL sites are designed to operate in the harsh winter conditions of the mountainous West. The stations provide continuous precipitation, snow water equivalent (SWE), temperature and snow depth information that is necessary to predict spring and summer runoff. Several (enhanced) stations are augmented to collect wind, solar radiation, relative humidity, soil temperature and soil moisture data to improve snowmelt runoff forecasting. Snow water equivalent is the amount of standing water in inches you would theoretically have at a site if all the snow were to instantly melt and if no loss occurred due to runoff, soil absorption and evaporation.
The SNOTEL system uses meteor-burst telemetry that reflects radio signals in the Very High Frequency (VHF) range off dust particles from disintegrating meteorites in the upper atmosphere. All SNOTEL sites communicate back and forth with Master Stations located near Boise, Idaho and Dugway, Utah. Collected data at SNOTEL sites is transmitted hourly to the Master Stations and then by landline to the NRCS National Water and Climate Center in Portland, Ore. for processing and distribution via the Internet to thousands of water users.
All 90 of Wyoming’s SNOTEL sites must be visited in the summer for repairs, modifications and to replenish expendables like batteries and antifreeze.
Manual Snow Courses
Measurements at the 64 Wyoming manual snow courses begin as early as the end of December, with the bulk of the courses starting to be measured the end of January. All courses are measured once a month from Dec/Jan to April or May, depending on the site.
At each site there are always two snow surveyors taking the measurements, and nearly all courses are visited by snowmobile, with some courses being over a 30-mile trip in one direction. Frequently the routes to these sites include ungroomed paths or trails requiring riding in deep snow. The surveyors, including non-NRCS cooperators, must attend a snow survey training school and be certified prior to engaging in this work. The training is heavily geared to winter survival.
At each site, the two-person team, which uses snowshoes to avoid disturbing the snow pack, uses “snow tubes” – handcrafted dur-aluminum tubes that screw together and have exterior markings for measuring snow depth and extracting a snow core. The snow core is weighed on a field scale and converted to inches of water. The data is carefully collected and sent to a Data Collection Office (DCO), which, depending on the part of Wyoming, could be Boise, Idaho, Bozeman, Mont. or Lakewood, Colo.
An actual snow course typically consists of five sample points that are generally in a line, though not always between two yellow end marker signs. The end marker signs inform the public of the course’s designation as a federal-state cooperative venture. In Wyoming, the State Engineer’s Office makes a significant contribution to the program. Other cooperators making contributions to the program in Wyoming include the Bureau of Reclamation (BuRec), National Park Service, and Teton Science School.
Farmer and Customer Benefits
The information provided by the Snow Survey and Water Supply Forecasting Program is essential to Wyoming’s economy. Irrigation districts, hydroelectric generators, reservoir operators, municipal water suppliers, flood emergency officials, wildfire managers and the recreation industry all depend on the information.
Irrigation districts and farmers use snow survey information to assess water supply and select crops for the coming year. Matching crops to forecasted water supply can have a significant impact on net farm returns. Increased income provided by using water supply forecasts varies from year to year and is dependent on crops grown, crop market, weather conditions and other variables.
The use of snow survey information is not limited to irrigation districts and farmers. Hydroelectric power generation potential is based on water supply forecasting, and the availability of water for power generation strongly influences power pricing and inter-regional power transfers.
Local disaster officials use data from the automated SNOTEL stations to issue flood hazard warnings. The Wyoming Highway Department provides avalanche protection and warnings in northwest Wyoming using the data from SNOTEL sites in the Jackson Hole area. Several communities use the information to determine the water supply available for their residents. Wyoming Game and Fish use the data as part of their wildlife management strategy. Other federal agencies, such as the BuRec and the Army Corps of Engineers, make reservoir management plans dependent on the information from this system. Many recreation enterprises depend on this data to plan rafting, canoeing, skiing and snowmobile activities.
The economic benefits of the program have increased significantly in the past 30 years as the West’s population and economy continue to grow and competition for limited water supplies intensifies. User access to Snow Survey Program information has been doubling every year for several years. News media coverage has been extensive, particularly with the banner 2010-11 snowpack year (2011 water year). During the winter, Wyoming newspapers publish many articles each week that contain Snow Survey and Water Supply information.
For more information contact the Wyoming NRCS Snow Survey Office at 307-233-6744/43 or visit our webpage at wy.nrcs.usda.gov/snow.
