The latest U.S. drought monitor comes out Thursday morning. The weekly map won’t bear good news. The March 5 map for South Dakota is awash in the red and deep red indicating the most severe grades of drought. The worst category is D4, which reflects “exceptional” drought, and that covers 29.58 percent of South Dakota, across the southern-most and many of the western-most counties. The second- and third-worst categories are D3 and D2, which are “extreme” and “severe” drought. They cover another 63.23 percent of South Dakota. In fact, all of South Dakota is rated in moderate to exceptional drought.
One year ago, none of South Dakota was rated in extreme or exceptional drought. Just 5.40 percent was even rated as in severe drought, and only 24.87 percent was rated in any kind of drought. On Monday the state water rights chief engineer, Garland Erbele, issued shut-off orders to 50 junior water-rights holders along the Cheyenne River and tributaries upstream of Angostura Reservoir. The reservoir is at 65 percent of storage capacity. The U.S. Army Corps of Engineers announced Tuesday the agency is implementing additional drought-conservation measures on the Missouri River ahead of the downstream navigation season that opens March 23 at Sioux City, Iowa, and on April 1 at the Missouri’s mouth near St. Louis where it meets the Mississippi River.
The corps is taking a two-step process to deciding on the navigation season. Initially the corps will release only enough water from Gavins Point Dam near Yankton to accommodate minimum service. That means enough water to support a navigation channel 200 feet wide by 8 feet deep. The corps in its announcement said this might mean barges need to carry lighter loads. A full-service channel is 300 feet wide by 9 feet deep. The corps will make a second decision after its July 1 storage check of the six major reservoirs, including the four in South Dakota and the other two in North Dakota and Montana.
The corps’ latest forecast for run-off above Sioux City is 20.0 million acre-feet, which is 81 percent of normal. The corps indicated in its announcement that a steady to rising level is preferred in each of the three large upstream reservoirs — Oahe in South Dakota, Garrison in North Dakota and Fort Peck in Montana — to assist in fish spawning during the April to mid-June period. If run-off isn’t sufficient to accomplish that, the priorities would be Fort Peck and Oahe “to the extent possible,” the corps announcement said. Mountain snowpack in the reach above Fort Peck is 94 percent of normal, and it is 86 percent in the reach between Fort Peck and Garrison.
Another effect of the drought is reduced electricity production from the six hydropower dams on the Missouri River. The power plants generated 557 million kilowatt hours in February. The normal amount for Februrary is 625 million. For calendar year 2013, the corps expects the power plants will put out 8.2 billion kilowatt hours. Normal is 10 billion.
The corps plans to announce its spring tour of meetings along the Missouri River in the coming days. The meetings are scheduled for April 8-12.