Boaters looking to get on the Mississippi River at the Coon Rapids dam boat launch will have to launch elsewhere this year. The dam is undergoing a $16 million upgrade to bolster its ability to stop the upstream advance of invasive Asian carp. The project will cut off access to the river from the boat ramp until 2014. Alternate launch sites just upstream are at Champlin and Anoka.

The Mississippi River behind the dam has been held at its current, elevated level — about 6 to 8 feet above summer flows — since February 2011 in hopes that carp would not be able to jump from the lower downstream level and spread upstream.

The river historically is drawn down for the winter, and the nearby boat ramp has usually remained closed until the river was deep enough for Three Rivers Parks officials to distribute warning buoys above the dam.

Water held back by dams on Minnesota rivers in winter is often drawn down as the spring thaw approaches, to make room for meltwater and limit flooding downstream.

Bill mCauliffe