JEFFERSON CITY, MO. ? The Missouri River has dipped to its lowest levels on record since the 1950s, when the once free-flowing river was restrained with a series of reservoirs constructed in upstream states, Missouri officials said Thursday.

The National Weather Service is projecting the river will continue to fall to levels not seen since the drought of the 1930s — long before reservoirs were built.

In compliance with a federal judge’s order in a lawsuit brought by environmentalists, the U.S. Army Corps of Engineers slowed water releases from upstream dams from 26,000 cubic feet per second, or cfs, to 21,000 cfs beginning Aug. 12 and continuing for three days.

Those reduced river flows are just now being noticed on parts of Missouri.

Thursday morning at Hermann, for example, the Missouri River was reported to be at 3.5 feet, a record low according to the state Department of Natural Resources.

As the river has fallen, water temperatures have increased and are close to exceeding Missouri’s water quality standards, a spokesman with the department said.

Low water levels have halted barge shipping and also could affect power generation, because Missouri River water is used as a coolant by several electricity plants.

“Part of the reason the Missouri River is low is drought conditions that exist in the region,” Missouri Gov. Bob Holden said in a statement. “However, another reason is that the U.S. Army Corps of Engineers is not releasing enough water to meet its obligations in the lower Missouri River.”

Conservation groups contend in their lawsuit that the corps previously has violated the Endangered Species Act by blocking the river from its natural ebb and flow.