Wildfires are a reality for those living in the American West…but the impact on the landscape lingers long after the smoke is gone. With an estimated two-thirds of U.S. municipalities getting their drinking water from a source that originates in a forest, fire and water are now inextricably linked. As part of Connecting the Drops, our state-wide series on water issues, Maeve Conran reports.
Allie Rae is a grad student at CSU who studies watersheds. She’s here at the Four Miles State Wildlife Area between Denver and Colorado Springs. It’s on the east side of the site of the Hayman Fire. That was the largest wildfire in the state’s history and it burned through more than 138,000 acres in 2012. The charred trees further up the hill are a reminder of the damage done to the landscape, but Rhea and other researchers are checking for other lingering impacts, not so visible to the naked eye. She’s here to monitor sensors in the creek.
“Basically In this black tube there are chords and they send signals back and forth…….”
These sensors measure how much water is flowing through this creek. Water that ultimately will end up in the faucet of a kitchen somewhere in Denver. Gauging the water quantity will help researchers get a better understanding of the water quality explains Chuck Rhoades, a research scientist with the US Forest Service.
“So if you are interested in the amount of nutrients that are getting into a reservoir or making it down to Denver you’ve got to multiply it by the amount of flow. So you can have milligrams per liter of nitrogen but this gives us the liters part, it tells us what that load is going to look like.”
And the nutrient load is high, a direct result of the fire. Trees that would absorb nutrients from the soil are dead and those nutrients are now going directly into the water.
“It’s more than 10 times higher than it was before, in some cases it’s 100 times above the baseline and so It’s quite elevated and having a stream of one parts per million of nitrate/nitrogen is something you wouldn’t expect from a pristine water shed.”
These levels don’t impact human health, says Rhoades, but they are indicative of a damaged ecosystem and that’s of concern to all water users.
“We’re not worried that we’re going to be poisoning people downstream with these levels of nutrients, but we are concerned that it can have an effect of the aquatic life, it might be altering what can live in these streams and changing the pristine nature of this water.”
Denver Water is paying attention to this type of research. They’re heavily invested in fire mitigation in the 2.5 million acres of watershed area in Denver Water’s Collection System. The source water starts at the mountain tops with precipitation, runs down through forests to streams, to reservoirs, on to treatment plants, and into our faucets.
Christina Burri is Denver Water’s Watershed Scientist. She says a watershed is vital infrastructure just like a water line or pipe.
“It all starts with the forests and healthy forests equal healthy watersheds.”
And when the watershed is damaged, it can impact the water supply.
“For instance after the buffalo creek and the Hayman wildfires, they were so high intensity, they sterilized the soil and caused erosion issues, and so because of the exposed soil and the sterilized soil, it runs off into our streams, into our reservoirs. We had approximately 1 million cubic yards of sediment going into Stroncha Springs reservoir after the Buffalo Creek and the Hayman wildfires.”
Burri says Denver Water is working with others in the watershed in their fire mitigation efforts.
“A term we like to use is an all hands all lands approach because the fire doesn’t stop at property boundaries and because the fire doesn’t stop at property boundaries, and because these fires, we’re predicting them to be more intense, more damaging to all the different interests of all the stake holders in the water shed.
Burri says these efforts pay off. Forest thinning done by Denver Water around Cheeseman reservoir actually saved homes and buildings during the Hayman fire. Denver Water is partnering with the U.S. Forest Service, the Colorado State Forest Service and Natural Resources Conservation Service in its forests to faucets campaign. So far 48,000 acres have been treated with forest thinning, clearing and creating fuel breaks as well as Restoration projects, helping forests become more resilient and resistant to future insect and disease epidemics which will further reduce wildfire risks.
There is surprisingly little data available on the long term impacts of fire on water sheds. Rhoades and his fellow researchers here at the Hayman site are hoping to change that with what they find here.
“We’re really in an area of new science because there have been few long term data sets that have exposed this kind of information and we’re just trying to get at it.”
With an almost year round fire season and an increase in bigger and more intense wildfires in the American West, it’s likely there will be other opportunities to study other fire damaged watersheds and build on this body of knowledge.