The High Park Fire burn scar will likely be a pain in the water supply in the Poudre for years to come

From the Fort Collins Coloradoan (Trevor Hughes):

Last fall, mudslides and rockfalls repeatedly blocked Colorado Highway 14 west of Fort Collins in the weeks following the High Park Fire. The spring runoff is poised to cause even more trouble in the coming weeks and years…

The most recent problem in the canyon came April 21, when several rocks the size of recliners tumbled off a steep embankment and onto the road, blocking the eastbound lane. CDOT workers on Friday did some emergency work to reduce potential rockslides.

And next month, state and federal workers will begin a series of projects aimed at keeping traffic moving on the road and keeping the water clean for drinking. Two major efforts launch next month: The first will improve culverts along the highway and reduce the amount of debris that can slide down hillsides. The second involves spreading straw on thousands of burned acres to help stabilize hillsides and aid in revegetation.

Wildfires burn off grasses, bushes and trees that help stabilize the ground, which is especially important on steep, rocky hillsides of the kind that flank the Poudre Canyon. Without roots, branches and fronds, water, rocks and ash can cascade down the hillsides, covering the flat road below before dumping into the Poudre River.

The river, an internationally known fly-fishing destination, ran black several times last fall as rains carried ash into it. That sludge is still visible in many areas, and its presence worries water managers.

The Poudre River is an important source of drinking water for many Northern Colorado cities, including Fort Collins and Greeley. The High Park Fire forced Fort Collins to change how it treats Poudre River water, something that helped drive a 4 percent water rate increase that took effect earlier this year. Runoff from the burn area has also caused spikes in iron and manganese in the river, and because of those and other pollutants — and treatment for increased algae in the river water — there’s a risk the taste and smell of the city’s tap water could change, affecting the city’s numerous breweries.

To help protect the supply’s quality and taste, Fort Collins has been using water from Horsetooth Reservoir to dilute or outright replace Poudre River water during periods of ashy runoff.

“We will continue to have the uncertainty of the Poudre River water,” said Laurie D’Audney, a city water conservation specialist. “We just don’t know how much of it we’ll be able to treat.”

The federal government, recognizing the impact that the fire’s lingering effects have on the water, earlier this month allocated nearly $20 million to Colorado to repair watersheds and perform flood mitigation work in the Waldo Canyon and High Park fire burn areas.

That work will help stabilize hillsides, to reduce the amount of water and debris running downhill. And CDOT’s culvert replacements aim to ensure the water that does flow down crosses beneath Colorado 14, rather than pooling atop it.

More restoration/reclamation coverage here.

Leave a Reply