Denver Water, partners, work on Hayman restoration
May 3, 2010
DECKERS – Eight years after Colorado’s worst wildfire devastated a vast swath of the Rocky Mountain foothills, erosion from the burn area continues to affect a key watershed for metropolitan Denver’s biggest water provider.
Over time, nature would eventually heal itself. But Denver Water can’t wait. The 2002 Hayman Fire, started by a U.S. Forest Service employee burning a love letter from her estranged husband, affected two reservoirs that are critical to the utility’s water supplies.
Denver Water is starting a $30 million project this fall to dredge its Strontia Springs Reservoir, where runoff from fire-scarred private and federal land has deposited tons of sediment into the 98-acre lake and reduced its capacity.
Immediately after the fire, the utility invested $8 million to rehabilitate land around nearby Cheesman Reservoir, clearing burned trees, planting new ones and building sediment traps on feeder creeks.
A third venture, scheduled to have started Saturday, 5-1 will accelerate the recovery of a 15-mile stretch of land between the two reservoirs some 40 miles southwest of Denver. The $4 million reseeding project is being funded by the National Forest Foundation, the U.S. Forest Service and Vail Resorts Inc., with completion scheduled for 2012.
“We really started to feel like the Hayman fire area was really not going to recover without intervention,” said Rob Katz, CEO of Vail Resorts, which is contributing $750,000 to the cleanup.
The Forest Service is matching Vail’s donation, and the Forest Foundation, will raise $2.5 million. Other nonprofits are contributing paid workers and volunteers to clear debris and plant grasses and Ponderosa pine trees over the 70-square-mile area.
The Hayman Fire charred 215 square miles and destroyed 600 buildings, nearly all within the Upper South Platte River watershed. It burned hot enough to melt earth into a crust that repelled water. Topsoil simply washed away after the fire. New plants could not take root in the damaged soil.
Today, the watershed shows few signs of recovery. Some grass is growing, but little more. Brian Good, director of operations and maintenance for Denver Water, said each rainfall sends rocky sediment rolling like ball bearings into the Platte and the two reservoirs. Spring thaws add rock, displacing more stored water. And heavy rains produce turbid water with high alkaline levels that must be diverted from the reservoirs.
“Anything done to help restore and stabilize the watershed will help us,” Good said, adding it would take another 12 years to to complete the restoration effort.
The burn area may have intensified damaging rains, said Brian Banks, a forest service project manager.
Some experts speculate that the barren ground absorbs more sunlight and energy, producing more heat to fuel storm cells, Banks said.
Denver Water serves 1.3 million customers. Cheesman Reservoir stores about 79,000 acre feet or about 26 billion gallons, enough to supply more than 158,000 households for a year. Strontia Springs holds about 7,863 acre feet – enough for 16,000 households for a year – in Waterton Canyon. From there the water eventually travels to the Foothills Water Treatment plant and metro Denver’s water taps.
The utility has spent $2 million to manage sediment traps on creeks feeding Cheesman. The traps consist of boulders piled into small dams that slow water and filter out debris before it enters the reservoir. A heavy rainfall can dump three feet of sediment behind the traps. Utility crews also place long buoys to stop dead trees and other objects.
Good and others worry about Strontia Springs and the potential structural damage posed by increasing sediment. Denver Water maintains a high water level in the reservoir to slow currents that push sediment toward the dam. But that prevents the utility from drawing on that water to meet demand when drought occurs. Officials hope the dredging plan will solve that problem.
Nowhere are the intricacies of soil erosion and water supply more visible than in the streams surrounding Deckers, a tiny fly-fishing mecca that sits between the two reservoirs at the confluence of Horse Creek and the Upper South Platte.
Sediment and rising water temperatures threaten fish habitat and Deckers’ livelihood. In some places, streams look like chocolate milk. Sediment from a flood last July is still piled high along the banks of Horse Creek.
That sediment which settles on stream bottoms pushes water outward against stream banks, eroding soil there. As the stream grows wide, straight and shallow, water moves more quickly, increasing erosion.
As Banks put it: “It’s like a perfect storm of erosion.”