DEVILS LAKE (AP) - Raising, extending and relocating existing dikes are the most viable flood-control measures for the Devils Lake Basin should the lake continue to rise, federal officials say.

The U.S. Army Corps of Engineers has been working on a $5 million study of future Devils Lake flood risks. The agency plans to outline its preliminary report in a series of public meetings next week, in St. Michael, Cooperstown and Devils Lake.

Upgrading dikes in the basin could cost hundreds of millions of dollars, according to corps estimates.

Devils Lake has expanded from about 40,000 acres to more than 130,000 during the past 15 years, because of sustained wet weather in the basin. More than $500 million has been spent in the past decade to raise dikes and roads and make other infrastructure improvements.

The U.S. Geological Survey says it is likely that Devils Lake will keep rising for at least the next 10 years.

The corps study initially was aimed at determining the potential need of raising the dike that protects the city of Devils Lake. It later was expanded to look at potential flood risk management measures throughout the Devils Lake region.

The corps also considered such potential measures as modifying the Tolna Coulee, increasing upper basin storage and relocating communities, such as Minnewaukan. Those suggestions came out of a series of public meetings in April.

The corps is not recommending any of those options, describing them as high-risk.

Engineers plan to spend the next couple of months developing cost estimates for dike work. Officials hope to complete the design of a final plan by December 2009.