March 18, 2010

‘Plenty of room’ in big lake

‘Plenty of room’ in big lake
The Garrison Dam spillway, which consists of 28 29-foot by 40-foot flood-control gates, has never been used for its intended purpose, according to Park Ranger Nathan Busche.
But it has come close. In 1997, the Lake Sakakawea reservoir rose to within a mere 4 feet of the dam’s maximum design elevation, allowing wind-aided waves to clear the spillway gates.
Last spring, the Corps completely cut releases for an extended period of time for the first time ever due to ice jam-induced flooding along the Missouri River in Bismarck. This spring, the Corps intends to gradually cut releases from the current 16,000 cfs to 10,000 cfs as the tributary flows come up, according to Garrison Dam Operations Project Manager Todd Lindquist.
The tributaries being monitored are the Knife River and Heart River, Lindquist said. As their inflows increase, Lindquist hopes cut releases will minimize the flood stage in Bismarck.
According to the Corps’ March Missouri River Water Management Monthly News Release, heavy snow and ice over much of the upper Missouri River basin and below normal snow in the mountains will probably result in heavy runoff this March and April, and much less in May and June.
The heavy snow pack on the plains is creating high potential for flooding on many of the rivers in North Dakota, South Dakota, Nebraska and western Iowa. In addition, because of the large buildup of ice on the rivers, ice jams may add to the potential flooding issues. Last spring, the Corps completely cut releases for an extended period of time for the first time ever due to ice jam-induced flooding along the Missouri River in Bismarck.
“It’s still too early to make reliable forecasts on potential flooding because so much depends on how much more snow accumulates, how fast it melts, and how much rain adds to the runoff,” said Jody Farhat, chief of the Corps Water Management Office. “Total storage in the reservoir system is less than our target for this time of year, which means we have plenty of room to collect runoff and hold water in the reservoirs when downstream river levels are high.”
 


The Weather Network