Boulder County approves proposed Longmont flood relief channel

Flooding in Longmont September 14, 2013 via the Longmont Times-Call
Flooding in Longmont September 14, 2013 via the Longmont Times-Call

From the Longmont Times-Call (John Fryar):

Boulder County commissioners on Tuesday approved Longmont’s proposal to build a relief channel intended to prevent a recurrence of the September 2013 sheet of stormwaters that flooded several westside city subdivisions.

In that flood, a breach on the north bank of the St. Vrain River resulted in floodwaters filling and overtopping ponds in Boulder County’s Pella Crossing open space area south of Hygiene, with the sheet of water eventually crossing Airport Road north of the river and the entering the city’s Longmont Estates Green, Champion Greens and Valley subdivisions.

Those neighborhoods are in an area that was never anticipated to flood during a 100-year flood event and that’s outside the previously mapped 100-year floodplain, county land use planner David Beasley said.

The Heron Lake Drainage Project getting the commissioners’ approval on Tuesday will include construction of a spillway on Heron Lake, the easternmost pond on the county open space, intercepting and deflecting floodwaters in the area and carrying them south toward the St. Vrain River rather than having them flow east into Longmont.

Dale Rademacher, the city’s general manager for public works and natural resources, said a contractor for the $700,000 project is expected to be chosen soon, with construction to begin by early February and completed by May 1.

Once that’s completed, the city will remove the temporary concrete flood-prevention barriers it installed along Airport Road…

The county’s approval of the joint application from Longmont, Boulder County Parks and Open Space and the Golden Land Company has several conditions attached, including the revegetation of the area once the work is done.

That revegetation is expected to comply with U.S. Fish and Wildlife Service standards to ensure that it will provide suitable riparian habitat in the future and “provide connectivity with an adjacent Preble’s Meadow Jumping Mouse habitat area, according to the county staff.

County commissioners congratulated the city, the county’s Open Space Department and the Golden Land Company for agreeing on a flood mitigation project the commissioners said will protect the environment, as well as residents of westside Longmont neighborhoods.

More South Platte River Basin coverage here.

Leave a Reply