FARGO, North Dakota (Reuters) - The Red River edged toward an expected crest on Saturday, when rain was predicted for the region that has been fortified against flooding by miles of sandbags, reinforced dikes and other protective measures.
The National Weather Service forecast possible thunderstorms for Saturday and rain through Sunday that could prolong the high water mark on the Red River that forms the border between North Dakota and Minnesota.
The rain could push the crest up a few tenths of a foot or more, said Greg Gust, warning coordination meteorologist for the weather service at Grand Forks, North Dakota.
"If we were to get yet this early evening a two-inch rain right over the Fargo community or the southern part of Fargo ... that would raise half a foot or more," Gust said.
A rapid rise from Wednesday to Friday at Fargo had slowed considerably by Saturday morning. The Red River stood at just over 38.7 feet on Saturday, and the weather service predicted it would reach about 38.8 feet by the evening.
"Typically a crest in Fargo on the Red is a slow and painful process," Gust said.
The Red River has already reached its fourth highest crest on record but is not expected to reach the 39.5 foot previous forecast. It reached a record 40.84 feet at Fargo in 2009.
Fargo has about 52 miles of protection in place to hold back the river, and hundreds of volunteers, state and federal emergency officials and National Guard troops were patrolling the dikes to watch for potential breaches.
Minnesota National Guard troops patrolled dikes and levees and monitored pumping on the Minnesota side of the river in Moorhead and other communities.
Fargo placed sandbags, added to dikes and completed other flood controls by Friday. It has 235,000 more sandbags prepared if the crest is higher than expected.
A crest in Fargo still means weeks of waiting and watching as the Red River recedes, followed by a similar process in Grand Forks and ultimately Winnipeg, Canada.
Rural areas north and west of Fargo have actually seen more significant flooding than in 2009 with the flows on Red River tributaries, Gust said.
The protections aim to defend roads, homes, farms and key electric and water treatment facilities, and authorities said experience of the past two years made them better prepared.
"It's a very significant flood, but at this time it certainly doesn't have the damage so far that we had in 1997 or 2009," said Gregg Wiche, director of the U.S. Geological Survey North Dakota Water Science Center.
Thousands of residents could be forced from homes and farms in North Dakota and Minnesota if the defenses are breached.
In Grand Forks, the weather service has projected a 51-foot crest, which would be the highest since 1997. While officials expect minimal impact because of flood walls added after 1997, two bridges already are closed by flooding.
The flooding was expected to have a major impact on the amount of land farmers will be able to plant this spring.
North Dakota has been the leading wheat-producing state the past two years and accounts for 16 percent of U.S. production.
On Friday, North Dakota Agriculture Commissioner Doug Goehring said the state's farmers could be prevented from planting 200,000 to 240,000 acres in the Red River Valley, the second-highest total in six years.
(Reporting by Richard Mattern, David Bailey and Rod Nickel, writing by David Bailey, editing by Ellen Wulfhorst)