Fire Fouls Water, Raises Costs
Investments in forest management can protect water resources
By Don Kennedy
It’s not the fire, but what comes next that devastates water quality.
Severe wildfire can remove vegetation from the landscape and leave soils exposed. When storms follow high-intensity fire, rain hits bare earth and can deliver massive sediment loads to streams and reservoirs. Denver Water will spend more than $30 million this year to dredge sediment and address water quality concerns stemming from the 1996 Buffalo Creek Fire and the 2002 Hayman Fire.
The Buffalo Creek Fire caused significant damage and served as a warning. The forests surrounding Denver’s reservoirs had grown uncharacteristically dense as active forest management in the area declined and aggressive fire suppression efforts extinguished low- intensity fire that could have naturally thinned the forest on Colorado’s Front Range. When fire entered the ecosystem, it burned much hotter and with greater environmental consequence than it would have if the forest had been mechanically treated to reduce fuels.
The granitic soil composition of the watershed exacerbated problems. Once the fire burned-off the leaves and needles that normally protect soil resources, the naturally granitic soils became like ball bearings ready to rush downhill. One storm after the Buffalo Creek Fire delivered 10 years’ worth of sediment to the South Platte River and led to 15 surface acres of debris that severely clogged the water delivery system. Sediment from Spring Creek entirely blocked the South Platte River and heavy equipment was rushed in to prevent the road from being completely blown-out.
Costs to treat the drinking water for 1.3 million Denver residents rose by $250,000 in the year following the fire because the water runoff contained elevated organic carbon, lead, copper, and chromium. Water-quality treatment, sediment and debris removal, reclamation and restoration costs related to the fires have already topped $11 million.
Thinning works
After the Buffalo Creek Fire, Denver Water initiated efforts to reduce fuel loads and sustainably manage forest resources. By the time the Hayman Fire hit, however, only a small portion of the forest treatments had been completed. When the fire reached parts of the forest that had been treated, flames dropped to the ground, buildings were spared and the impact on water quality was minimized. The fire burned severely in areas around Cheesman Reservoir that had not yet been treated, however, and straw-bale dams, sediment traps and other emergency measures had to be put in place to protect the reservoir from debris flows and sediment.
Denver Water might have potentially saved millions had we sustainably managed the forests around our reservoirs before these fires occurred. Thinning the forest would have served as an ounce of prevention, and been more cost-effective than the pound of cure that became necessary.
Now, efforts to conserve Denver’s water resources include restoring forests and reducing fuel loads so future fires are less severe and their impacts less costly to mitigate. In many places we are mimicking natural effects through mechanical harvesting because forests are too dense to safely introduce low-level fire which could aid thinning efforts.
New funding mechanism tapped
An innovative solution whereby Denver Water is helping fund upstream stewardship is at the heart of restoration efforts. Denver Water has entered into a partnership with the USDA Forest Service in which each are sharing the expense of restoration to improve ecosystem function and ultimately protect water quality. The “Forest to Faucet” public-private partnership has been entered into with the objective to sustainably reduce the risk of catastrophic fire to critical watersheds that provide municipal water supply.
Under the five-year agreement, the USDA Forest Service is matching funds put forth by Denver Water to ensure stewardship of watershed resources. Denver Water customers have been well educated on the benefits of managing forest resources, as well as the risks posed to their water supply if fuel loads are not reduced. Our customers will pay $27 on average over the five-year agreement to help fund forest restoration with the understanding that an investment is being made in potential long-term savings and water-source security. The Forest Service ensures regulatory compliance and directs on-the-ground forestry activities, and Denver Water helps pay for sustainable fuel reduction efforts.
Raising public awareness of the threats that severe wildfire poses to water resources was essential to establishing the Forest to Faucet partnership. It was also important to prioritize watersheds for treatment so that work will begin where it is most critically needed. We are in the first year of the partnership and forest treatments have begun within the upper reaches of the South Platte watershed.
Denver Water understands how important it is to manage forests to help reduce the risk to water supplies from catastrophic wildfires. Ours is an experience others can learn from. In watersheds where dangerous fuel loads have accumulated, thinning the forest to reduce wildfire severity can save money, restore ecosystem functions and protect water resources.
Articles
The forests had grown uncharacteristically dense as active forest management in the area declined.
One storm delivered 10 years’ worth of sediment and led to 15 surface acres of debris.
Thinning forests to reduce wildfire severity can save money, restore ecosystems and protect water resources.