Washington ? The U.S. Army Corps of Engineers will not release extra water from upstream reservoirs this spring to boost flows on the Missouri River, the agency announced Wednesday.

The corps said the reservoirs’ water levels are too low to have the spring rise, which is done to encourage spawning by the pallid sturgeon, an endangered fish. Since 2005, agency plans have called for two pulses of water, one in March and one in May.

No release will be conducted this month because reservoir levels have not reached the minimum of 36.5 million acre-feet of water, said Paul Johnston, a spokesman for the corps’ northwestern division office in Omaha, Neb.

Water levels must be even higher for the May release, and Johnston said none of the agency’s computer forecasts show levels getting high enough.

The spring rise has long been contentious among states along the river. Missouri officials oppose the plan because of possible downstream flooding and interference with the barge industry. Upstream states are reluctant to part with water that could deplete lakes and harm boating and fishing interests.

Last year, the corps also was forced to cancel the March pulse because water levels were low, but the May release went on as planned, despite a federal lawsuit to stop it filed by Missouri Attorney General Jay Nixon. The release caused no flooding and a federal judge later rejected Nixon’s lawsuit.

The corps established guidelines for the spring rise after the U.S. Fish and Wildlife Service called for greater protection for the pallid sturgeon under the Endangered Species Act.