Ice forming on the James River in LaMoure County caused the river level to rise nearly a foot between Sunday evening and Monday morning, according to Kimberly Robbins, LaMoure County emergency manager.
"The water temperature is below zero degrees Celsius so we're forming shore ice and ice in the river channel," she said. "... There is broken ice hanging up against railroad trestles. Smaller ice chunks now."
The James River level at LaMoure jumped from 11.3 feet at 10 p.m. Sunday to 12.1 feet at 10 a.m. Monday, Robbins said.
"At 12 feet, we're at the 'action stage' for the city of LaMoure," she said.
The city of LaMoure has been at or above the action stage for several weeks this fall. When that occurs, the city plugs its stormwater drains into the river and pumps any accumulated stormwater into the river.
Releases from the Jamestown and Pipestem dams are being reduced due to the ice jams downstream, according to Jerry Bergquist, Stutsman County emergency manager and 911 coordinator.
Plans from the U.S. Army Corps of Engineers called for releases of 500 cubic feet per second from each dam on Monday with a reduction to 400 cfs from each dam planned for Tuesday, he said.
"Wednesday, they'll leave the Jamestown Dam where it is but reduce the Pipestem Dam to 250 cfs for combined releases of 650 cfs," Bergquist said.
The reduced releases are close to the actual inflows into the two dams, Bergquist said.
Inflows at Pipestem Dam were 250 cfs Monday while Jamestown Dam reported inflows of 352 cfs at the same time.
The level of Pipestem Dam is down about 15 feet from the peak of 1,475 feet above sea level. The reservoir level must drop another 18 feet to be at its planned level by spring. The water behind Jamestown Dam is down less than 2 feet from its peak of 1,442 feet above sea level. Plans call for its level to be reduced by 11 feet before springmelt.
The lower river levels resulting from the reduced releases from the dams will take about five days to reach LaMoure, Robbins said. In the meantime, local officials are monitoring the situation and plan to use a drone to videotape the trestles. The video would be furnished to the Corps of Engineers and the National Weather Service for review.
Up to 11 inches of new snow over the weekend compounded the possible flooding problems in southern LaMoure County, Robbins said.
"Right now we're in snowplowing mode," she said Monday morning.