The City of Longmont will soon begin construction of the Heron Lake Relief Channel; this is a flood mitigation project intended to protect neighborhoods on the west side of Longmont that suffered damage in the 2013 Flood. The project is the result of a partnership among the City of Longmont, Boulder County, and the Golden Land Company, and it is an example of the region’s commitment to furthering resiliency along St. Vrain Creek.

Flooding in September 2013 caused severe damage in Longmont’s western neighborhoods of The Greens, Champion Greens, Golden Ponds Estates and the Valley subdivisions. Over 400 properties were affected as well as public infrastructure. The flood hazard in this area was not identified in previous floodplain studies; however, in 2013 a breach of upstream St. Vrain Creek banks led to a series of mined gravel pit breaches that eventually reached Heron Lake and then continued eastward into Longmont.

The Heron Lake Relief Channel was conceived by the City of Longmont from the experience and observations of the 2013 flood event. The idea was later confirmed by hydraulic modeling of this area. The project consists of an open drainage channel that can intercept flood waters in Heron Lake, which is on county open space property (half a mile west of Airport Road), and divert this water back to the St. Vrain Creek.  It is designed to convey a 100-year flood and protect the western neighborhoods from future flood events up to the 100-year flood.  

The project would not be possible without participation and support from three parties: the City of Longmont, which is the project lead agency; Boulder County, which owns open space property at Heron Lake and adjacent to the St. Vrain Creek; and the Golden Land Company, which is the property owner for the majority of the project site.  

Construction of the project was initially planned to begin in February 2015, but was delayed to address environmental and wildlife issues in the area, including the presence of the Preble’s meadow jumping mouse, and the establishment of a bald eagle’s nest. The project participants have worked with the U.S Fish and Wildlife Service to resolve the environmental issues and protect these wildlife species. The City of Longmont and its partners are committed to flood control projects that protect both people and the environment.

The total project cost is estimated at $925,000. Boulder County will contribute $100,000 of FEMA-reimbursed funds to replace flood-damaged facilities as part of the project, and has been contributing to the project engineering and planning from the beginning. The City of Longmont will pursue Community Development Block Grant Disaster Relief funds for the remaining project costs. Construction is scheduled to start the first week of August and will be completed before the end of 2015.

“We applaud the collaborative nature of this effort to make homes on the west side of Longmont more resilient to future flooding,” said Boulder County Commissioner Chair, Deb Gardner. “City and county staff have put in many hours to ensure that this project will help divert water back into the creek channel where it can safely bypass homes that were so hard hit during the 2013 Flood.”

This news marks another step forward in Longmont’s flood recovery and protection efforts. To learn more, visit LongmontColorado.gov/flood-info.