GRAND FORKS, North Dakota (Reuters) - Flood fighters patrolled strained levees on a Red River tributary and an old dam on a northwest North Dakota river on Thursday as forecasters reduced the projected crest in Grand Forks.
About 100 North Dakota National Guard members watched the levees around Valley City, reinforcing weak spots in the levee system along the Sheyenne River that is expected to crest within inches of its 20.7 foot record there on Friday.
"There was one part of a levee that we had issues with last year too that started to slip," Shannon Bauer, a U.S. Army Corps of Engineers spokeswoman, said Thursday. "We put in a contingency dike behind it."
Bauer said flood fighters also built a clay dike along Main Street in Valley City to reinforce a temporary barrier made of sand-filled barriers leaking under the strain of the water.
Engineers have added twice to levees in the Valley City area in anticipation of the near-record crest. High flows on the Red River have also left the Sheyenne spreading out across communities near where it meets the Red River north of Fargo.
In northwest North Dakota, the weather service has a flash flood watch in effect until Saturday for Burlington residents near a small dam that could fail on the flooded Des Lacs River. However, river levels were easing on Thursday.
In Grand Forks, the National Weather Service on Thursday trimmed a foot from its projections, but was still expecting the Red River to reach its third highest crest on record.
"The Red River is starting to flatten out now, we are still looking at a crest close to, maybe just under, 50 feet within the next 12 to 24 hours," Al Voelker, a meteorologist with the National Weather Service in Grand Forks, said on Thursday.
With permanent barriers built after the 1997 floods now protecting Grand Forks and neighboring East Grand Forks, Minnesota, the focus is more on smaller nearby communities.
The Red River crested Saturday at Fargo earlier and lower than forecasted. However, smaller communities and farms north and west of Fargo have been hit hard by flooded tributaries.
Once past Grand Forks, the Red River flattens and grows to eight miles wide or more during floods, making numerous roads impassable, isolating some farms in North Dakota and Minnesota and making the small city of Oslo an island for days.
This year's expansive flooding was expected to have a major impact on the amount of land North Dakota farmers will be able to plant this spring.
The river ultimately flows through Manitoba, Canada, into Lake Winnipeg. Canadian towns have been preparing defenses for weeks and the provincial government is set to close the major link between North Dakota and Winnipeg, Highway 75.
Winnipeg expects the second-highest crest on record as early as late April.
(Writing by David Bailey; Additional reporting by Doug Barrett and Rod Nickel; Editing by Greg McCune)