An $11 million reconstruction project between Lyons and Longmont will bolster St. Vrain Creek against flooding and turn the waterway into a better home for area raptors and other birds, a Boulder County official said Monday.
“This is a really big project, and needed because it was hit hard during the flood,” Justin Atherton-Wood, senior planner with Boulder County Parks and Open Space.
St. Vrain Creek was washed over during the September 2013 floods that killed eight people and caused $2 billion in damage. Flooding also isolated Lyons for several days.
As part of the county’s effort to rebound from the floods, Boulder County commissioners last year approved spending nearly $10 million on the Lake 4, West Lake and A-Frame dam rehabilitation project. Work crews are rebuilding four earthen embankments breached during the 2013 floods and three reservoirs on the county’s Western Mobile, Braly and Ramey open space properties.
Lake 4 is owned jointly by Boulder County and the St. Vrain and Left Hand Water Conservancy District.
The cost of the project has since gone up, mostly because crews had to process sediments taken from Lake 4 to use as proper backfill. That cost $1.3 million, Atherton-Wood said.
The project is still expected to come in $2 million below original estimates, Atherton-Wood said.
The area is located south of the St. Vrain Creek and west of North 61st and 63rd streets just west of Hygiene.
The project, which began in September 2019 by Kirkland Construction, is expected to be completed by Sept.1, said Atherton-Wood, who is helping oversee the construction.
Work crews have been using heavy bulldozers, excavators and off-road haul trucks over the course of the project. Nearly 20 loads of sand, gravel and rubble are being brought in to help rebuild the reservoirs by the way of Colo. 66 and Hygiene Road, the county said.
The county wants to restore water storage and delivery function of Lake 4 and the configuration of the other reservoirs as they were before the September 2013 floods.
Crews will repair the four separate breaches in the reservoir embankments. They also will install outlet structures and emergency spillways for each reservoir, Atherton-Wood said.
The project will improve the “resilience” of the reservoirs and the surrounding landscape in the case of future flooding by building a more defined and controlled flood path.
Water fowl, especially raptors, will find a more settled habitat. “It will be a much better place for them to live,” he said.
More than 200,000 cubic yards of sediment is being removed from Lake 4 and reused as fill over the course of the project, the county said.
The project is funded by grants from FEMA, HUD and a loan from the Colorado Water Conservancy Board.
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