National Climatic Data Center, 15 July 2004

South Dakota's largest man-made reservoir, Lake Oahe, hit an all-time low Thursday of 1,576.16 feet above sea level, but it could fall several more feet before the end of summer.

Oahe, which was completely filled in 1969, is one of six reservoirs that make up the largest system of lakes in North America, draining one-sixth of the continental United States.

However, lingering drought continues to shrink the lakes.

Oahe is expected to fall 3 feet this month, ending July about 33 feet below normal and 11 feet lower than a year ago, according to the U.S. Army Corps of Engineers.

Larry Cieslik, chief of the corps' Missouri River Basin Water Management Division, said Thursday that Oahe may fall to 1570.8 feet by the end of August and begin rising again in September.

The shortage of water prompted the corps to announce last week that the downstream navigation season will be shortened by 47 days.