Erosion from ‘02 wildfire fouling reservoir supplying Denver

Erosion from ‘02 wildfire fouling reservoir supplying Denver

24 November 2006

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Longmont,CO, USA — Erosion from hillsides left barren by the devastating Hayman wildfire of 2002 is dumping tons of mud, ash and decomposed granite into Cheesman Reservoir and creating expensive problems for Denver’s water utility.

The reservoir about 30 miles southwest of Denver is a key source for the Denver Water Board, the state’s largest utility with 1.1 million customers.

Researchers estimated as much as 3.1 million cubic yards of sediment would drain into the reservoir in the first five years after the fire, but water board officials said they believe the volume is much higher.

“We were told it would stabilize in five years,” Kevin Keefe, superintendent of source supply for water board, told The Denver Post in Friday’s editions. “This is Year Four. It’s not getting better. It’s getting worse.”

The water board says it has spent 7.8 million over the past four years to remove sediment, replace culverts, build sediment dams and seed slopes.

Utility officials estimate it would cost an additional 20 million to remove an estimated 1 million cubic yards of debris from previous fires from Strontia Springs Reservoir, downstream from Cheesman.

Utility managers have said they are concerned the muck could eventually fill in Cheesman, gumming up pipelines and rendering the water system ineffective.

Keefe said he believes problems will persists for decades.

The reservoir was at the center of the Hayman fire, the worst in the state’s recorded history. It scorched 138,000 acres southwest of Denver.

The watershed there endured some of the fire’s most intensive heat and the forest on it was destroyed, destabilizing the slopes that drain into the reservoir. A Forest Service study said about 56 percent of the burned area drains directly into the lake.

The Denver Water Board plans to plant 25,000 trees a year for the next seven years to try to restore the slopes.

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