PIERRE, S.D. (KELO) — The U.S. Army Corps of Engineers allowed Missouri River water to keep flowing through Oahe Dam at the planned rate of 30,000 cubic feet per second Wednesday.
But half of that flow had to be routed through the dam’s regulation tunnels into the stilling basin on Lake Sharpe, rather than through the dam’s hydropower turbines.
That’s because some etransmission lines carrying electricity from the dam were out of service,, according to project manager Eric Stasch.
He said it’s possible that conductors on the lines were bouncing in the wind and would simply have to be re-set.
But he acknowledged there could be a transmission line actually on the ground or there could be some other problem.
The situation won’t be known until Friday at the earliest, however, because the crew didn’t go into the field Wednesday and won’t head out Thursday in blizzard conditions, Stasch said.
The flow through the dam will continue at 30,000 cubic feet per second in the meantime because that’s what the corps previously planned.
But half will keep running through the stilling basin until the problem can be found and the lines brought back on.
“This is totally unplanned,” Stasch said.
A KELOLAND reporter drove to the stilling basin Wednesay afternoon after talking with Stasch and saw huge chunks of ice moving downstream at a faster than usual rate for the basin.
Meanwhile snow driven by wind made the dam’s powerhouse impossible to see as the reporter drove across the top of the dam.
The discharge tunnels in the stilling basin couldn’t be seen either through the snow from the bridge that crosses not far downstream.
Corps officials had to cancel their scheduled spring stop Wednesday morning in Fort Pierre because they didn’t feel safe flying through the storm into Pierre from Bismarck.
They instead flew to their next stop in Sioux City, Iowa, where a full house turned out for the late Wednesday afternoon meeting.
The two Missouri River reservoirs upstream, Fort Peck in Montana and Sakakawea in North Dakota, still have room for snowmelt this spring, but Oahe is nearly full.
Other downstream Missouri River tributaries such as the White, Niobrara, James and Big Sioux rivers have been running high after a March blizzard.
In turn the corps has been running water through the three lower reservoirs at a faster rate.
The corps meanswhile sent a message Wednesday on Twitter about the situation at Oahe.
There are some power lines down near Pierre, SD from the storm. As a result, we have to generate less power at Oahe Dam.
This means needing to release water through the regulation tunnels instead of the powerhouse. Release rates are unchanged.— USACE NWD (@NWDUSACE) April 10, 2019
The corps sent another tweet about 90 minutes later clarifying the situation. It said:
“***Correction – Transmission lines are offline – there is not confirmation that the lines are down.”