North Platte Reservoirs Up; One Full
June 19, 2009
McConaughy Now Over 50%Reservoirs in the North Platte watershed have nearly doubled their storage during the past two years due to a combination of near normal snow melt, above normal early crop season moisture, and reduced water transfers for irrigation. As of June 16 the four largest reservoirs contained 2.83 million acre-feet of water which is 63% of capacity.
Mountain snow melt has peaked but continues to a lesser extent and is expected to push total storage close to 3 million acre-feet before levels begin dropping to meet irrigation demand. May projections indicated streamflows from snow melt would run 85%-90% of normal. However, above normal moisture since early May has offset the sub-par projections and is replenishing the Wyoming reservoirs.
As of June 16, Seminoe Reservoir had 891,000 acre-feet of water equating to 87.6% of capacity. Seminoe is only 6.5 feet below full pool and there is a chance that it could fill if above normal moisture continues through June.
Pathfinder Reservoir had 489,000 acre-feet in storage and is at 48.1% of capacity. Based on current and projected inflows, Pathfinder should reach 55%-60% of capacity.
Glendo Reservoir has 525,000 acre-feet of water in storage which is 100% of capacity. If last year is an indication, Glendo will add another 35,000 acre-feet into the flood pool. Full water allocations should be delivered to eastern Wyoming and western Nebraska irrigators. This should help streamflows coming into Lake McConaughy by reducing upstream pumping of the alluvial aquifer.
Lake McConaughy had 924,600 acre-feet of water June 17 which is 53% full. On this date last year Lake McConaughy was at 803,400 acre-feet. Without the May pulse flow releases, McConaughy would have reached one million acre-feet. McConaughy has experienced a 25,000 acre-foot gain in the last week, bolstered by last week's severe weather near Scottsbluff.
If drought conditions don't develop this year and the Rockies get normal snowfall, all Platte River reservoirs upstream of McConaughy are likely to reach full pool next year. If this occurs, McConaughy should exceed 70% capacity next spring due to increased water releases from Wyoming reservoirs.
Allen Dutcher, State Climatologist
Nebraska State Climate Office
School of Natural Resources