Figure 1. Snow water equivalent (inches) above Seminoe reservoir, March 30, 2012. The green line shows levels for 2011-2012, the black line shows average snow water equivalents, and the red line shows 2011 levels. (See larger version.) (Source: U.S. Bureau of Reclamation)	Figure 2. Reservoirs in the North Platte River Basin were mostly at or near capacity as of March 29, 2012. (See larger version.) (Source: U.S. Bureau of Reclamation).

April 5, 2012

North Platte River Reservoirs Near Capacity, but Conservation for Tomorrow Urged 

What a difference a year makes. Last year at this time we were not worried about whether we would have enough water for irrigating, but rather how we could move water downstream to avoid flooding.

Last year at the end of March snow water equivalent was at nearly 33 inches and climbing, more than 10 inches above normal (Figure 1). This year the snow water equivalent is approximately 14 inches and falling, nearly 10 inches below normal. We can continue to gather snowfall moisture for another month; however, the trend in the last month has been in the wrong direction.

This is not to say that we are short of water for irrigation. Figure 2 shows the major reservoirs on the North Platte system. Seminoe, Pathfinder and Glendo, the largest reservoirs, can hold a total of over 2,500,000 ac-ft of water. The system only needs an additional 400,000 ac-ft to be filled to capacity. Because water will be moved downstream to fill Lake Minatare and additional water can be moved downstream to relieve stress, it is unlikely we have to be concerned about much flooding this year. Also, the newly completed spillway extension on the Pathfinder dam is providing additional storage space.

Just a few short years ago these diagrams looked much different. Snowpack was below average and the reservoirs were nearly empty. Irrigators were living from year to year on snowpack and wondering how many acres to plant. There was little talk of trying to do a hay run and speculation was high on just how long the water would last into the late summer.

Irrigators in the North Platte River valley should remember that just a few years ago these reservoirs were just about empty, but then refilled to capacity in about a year. What happens if the dry conditions we experienced just a few years ago return not only in the coming year but into the next several years. If you look at long range forecasts, temperatures in April are forecasted to be above normal. (See Figure 3.)

In fact, if you look at long-range forecasts for the next year, there is a greater chance for above normal temperatures than average temperatures. The precipitation forecast for April, shown in Figure 4, indicates below normal precipitation for most of the Panhandle. For the coming year, the maps indicate equal chances for above or below normal precipitation, except during the 2012 harvest season, when above normal precipitation is predicted.

Remember, these maps are only forecasts, but lessons learned in the last few years would tell us the time to save water is when you have water to save. That time is now. Consider your irrigation practices and what methods to use to reduce your water use and leave more in the Wyoming reservoirs. That way, if drought does return, we have already started to conserve and store water for our future needs.

Related Information Resources

• The March 30 CW story, Two Cost Effective Tools to Improve Irrigation Efficiency - Order Now for Spring Installation
• Nebraska Agricultural Water Management Demonstration Network (NAWMDN), a statewide record of soil moisture readings and crop water use information
• Water.unl.edu, a comprehensive information resource on water, including water for irrigation.

C. Dean Yonts
Extension Irrigation Engineer, Panhandle REC