Cleaning up the confluence

Denver Water is still haunted by forest fires that burned three decades ago.

Fire-blackened landscapes left vulnerable to heavy rains unleashed thousands of tons of sediment that poured into the South Platte River, the North Fork of the same river and, soon enough, the utility’s Strontia Springs Reservoir southwest of Denver.

The resulting sediment buildup even today continues to affect water storage, clog dam workings and degrade water quality, forcing costly efforts to remove it and address the damage.

Ever since, with the hard lesson learned, Denver Water has sought to reduce the flow of sediment into rivers and reservoirs. It partners with land management agencies and organizations on projects that reduce the risk of catastrophic fires and limit damaging erosion and debris flows.

This spring, with help from the Jefferson Conservation District and state gaming revenues, Denver Water completed one of the dozens of landscape management projects it has tackled since 2010 — this one at the confluence of the North Fork and the mainstem of the South Platte near Foxton. Two Colorado companies, Matrix Design Group and Total Terrain, completed the project.

Crews restored a section where the two rivers meet to stabilize and revegetate riverbanks, slow and redirect water and trap sediment. The work, just two river miles west of Strontia Springs, prevents more sediment from reaching the reservoir and protects one of Denver Water’s most important water storage sites.

“This project was a big one for us, as it limits a source of sediment right above Strontia,” said Sarah Hodson, an engineer who managed the project for Denver Water. “Making these improvements to the river environment now is an investment in the future, as it will limit erosion and water quality problems for many years to come.”

The project took place within the footprint of the 1996 Buffalo Creek fire, an intense wildfire that burned nearly 12,000 acres and was followed two months later by a waterlogged thunderstorm that dropped 2.5 inches of rain and sent thousands of tons of sediment downstream.

The impacts of that fire — along with the massive Hayman Fire of 2002 — and the ensuing torrential rains that came after are still being addressed today as Denver Water works to protect Strontia Springs, a reservoir atop Waterton Canyon that delivers water to two major treatment plants before distribution to 1.5 million people. 

Catastrophic wildfires have increased in scale across the West, and in 2010, recognizing the threat such fires posed to water quality, Denver Water teamed with organizations that included the U.S. Forest Service to create the From Forests to Faucets partnership.

That partnership, which also features the Colorado State Forest Service, the Natural Resources Conservation Service and the Colorado Forest Restoration Institute, has devoted $96 million to reduce wildfire risk across more than 120,000 acres over the last 16 years, the bulk of that within the South Platte River Basin.

The sediment reduction project near the confluence of the North Fork and the South Platte enjoyed a new twist: funding for the work came largely from Colorado gaming revenues set aside by the legislature for water projects and administered by the Colorado Water Conservation Board. 

Since sports betting became legal in Colorado in 2020, the state's Division of Gaming said it has raised more than $100 million for water conservation, and expects to hit $120 million after this fiscal year, according to reporting by Denver 7, which produced a story on the sediment control project at the confluence. 

"Sports betting has really been instrumental to this project," said Margo Yousse, the watershed project manager with the Jefferson Conservation District, a key partner on the project.

Yousse told CBS4, which also covered the project, that the goal of the project is to keep the sediment in place by slowing water down with anti-erosion structures as well as seeding and planting trees.

Added Youse: "The more work that we can do to protect the watershed higher up in the hills, then it's ultimately going to benefit everyone downstream with healthier, cleaner water to drink.”