A northerly Grand Forks dam “appears to be in good condition and functioning as intended,” city staff told Grand Forks City Council members on Monday.
An annual city inspection conducted last week found no significant erosion on either bank of the Riverside Dam, which spans the Red River near Riverside Park. The inspector, Principal Civil Engineer David Kuharenko, took a series of photos along both banks and a nearby pedestrian bridge and compared them to ones taken at the same spots last year. He told council members that he found no significant displacement of “riprap” -- the loose stones used to buttress the dam -- or significant secondary damming, which is when sticks, trees or other debris get caught in the dam.
The 320-foot dam was originally built in the 1920s to ensure a water supply for Grand Forks and East Grand Forks. It was replaced in the late 1980s.
The North Dakota State Water Commission inspected it most recently in 2009, which, according to its 10-year schedule, would mean another state inspection is due this year.
But, explained Kuharenko, the state is set to downgrade the dam from a “medium” hazard one to a “low” hazard one. The dam was characterized as a medium hazard because, if it failed, the result would strain the city’s water supply upstream in addition to flooding areas further downstream.
After a re-evaluation of downstream effects, which would be relatively minor given that the dam is north of most of Grand Forks proper, the lower hazard rating was awarded resulting in less frequent inspections.