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Home / Articles / News / News /  Watershed woes
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Thursday, June 16,2011

Watershed woes

Runoff from Fourmile mines could taint local water quality

By Elizabeth Miller

Sheila Murphy wades into Fourmile Creek, her waist-high beige waders keeping her submerged legs dry. She rinses a plastic container out in the creek, then takes a sample. At the creek bed, she tests the water’s pH and temperature, baseline measures for the health of the stream. Her colleague, Jeff Writer, pulls another testing device out of the water downstream and checks conductivity — the total amount of dissolved ions in the water.

Murphy and Writer, both hydrologists with the U.S. Geological Survey (USGS), have been studying Fourmile Creek since the first rainfall after the Fourmile Fire, working to better understand the fire’s effects on the stream ecology.

Researchers, public health officials and managers of downstream watersheds have been monitoring the water quality of streams throughout the burn area and how they might be affected by an increase in sediment, plant matter and even heavy minerals.

On Oct. 10, just a month after the fire, a multidisciplinary, multi-agency team filed the Fourmile Emergency Stabilization Burned Area Report, which declared the area a watershed emergency because of the threats to human life and safety, roads and downstream water supplies. While officials and researchers say the risk is low to moderate, they also admit there are a lot of unknowns at this point and that a severe rainstorm could have a major effect on water quality.

“The interesting thing about the Fourmile Creek watershed is historically it was a major mining area,” Murphy says. “So there are quite a number of mine tailings piles and waste rock in the watershed that, without the trees around and grass and shrubs to protect those piles, there’s a concern that if there was a really big rainstorm or something it could wash a lot of metals that are typically in higher amounts in tailings pilings into the creek, which would also be a problem for drinking water issues and for aquatic life in the stream.”

When she and Writer checked water quality during the first rainstorm after the fire, it showed a pulse in conductants — dissolved matter in the water including organic carbon, or plant matter, and nitrates. They try to sample during every storm.

“The stream hasn’t run black, and we haven’t seen really major things, but by the same token, the weather patterns this winter and spring have been pretty benign,” Writer says. “So what we’re hoping to do is be able to continue to look at it, because things could totally change.”

Murphy worked on mine site impacts before joining the USGS and visited the burn area before the fire. The first thing on her mind when the fire happened were the mines, she says. The focus of her research now is on the metals that might appear in the drinking water.

As the Burned Area Report suggests, the issues facing recovery from the fire are layered — one of the bridges Writer draws samples near is at risk of washing out if the area gets more than an inch of rainfall. The emergency stabilization that the plan proposes includes mulching steeper slopes that were moderately or severely burned, seeding and clearing pathways and establishing warning systems for flash floods.

The report was used in an application to the state of Colorado that prompted Gov. Bill Ritter to reappropriate half a million dollars for Boulder County to take emergency steps to protect water quality.

Ritter’s executive order drew from a remaining balance in the Water Quality Improvement Fund, which is typically given out in small grants to help communities improve water quality.

“We were operating under an emergency, and there was this fund balance sitting there,” says Donna Davis, operations program manager for the Water Quality Control Division for the Department of Public Health and Environment.

“We’re going to be very close to spending all $500,000, and the majority of it is from the aerial mulching,” says Claire DeLeo, senior plant ecologist with Boulder County Parks and Open Space and team leader for Fourmile Canyon rehabilitation, which led the aerial mulching and seeding projects. The mulch acts like vegetation, covering the ground from rainfall and helping it absorb moisture.

DeLeo estimates that as much as $450,000 of the state grant went to aerial mulching. In total, the two-week project cost about $2.3 million and covered 1,960 acres. That comes to about $1,143 per acre. The total cost of suppressing the fire on all 6,179 acres was $9.5 million.

“The aerial mulching was a big project. We spent a lot of money,” DeLeo says. “Now we have to see if it worked. We won’t really know until we get a thunderstorm.”

A volunteer crew raked in seed on about 450 acres, mostly along roadsides and driveways, to control noxious weeds. The spring rains have helped the seeded areas to sprout, though they won’t provide good erosion control for at least another year.

“When you think about downstream water quality, it’s the whole erosion aspect, so everything we’re doing with erosion is going to help with downstream water quality,” DeLeo says.

“We targeted the high- and medium-burn severities, and so that meant that there were some areas that did not get mulched,” DeLeo says. “They might erode, but they are not high-risk.”

If a mine happened to be in an area targeted for mulching, it was mulched over, she says, but mines were not specifically targeted.

“It wasn’t specifically in our funding for the fire rehabilitation, mostly because the risk was really unknown. It was really not known what kind of risk would be possible from these mines,” DeLeo says.

The mines are old, and the tailings are considered stable. But the county was one of the most densely mined in the state, and abandoned mine hazards are located throughout the burn area.

“We have a lot more features we didn’t even know were there before,” says Bruce Stover of the Colorado Division of Reclamation, Mining and Safety. “So we’re trying to inventory those so we can go back in and do maintenance on closures we did before, or do new closures on mines that we weren’t aware of before.”

Miners in the area were digging after the northeastern extension of the Colorado Mineral Belt, the same belt that caused gold rushes near Central City, Idaho Springs and Leadville. Precious metals like gold and silver were the main attractions, Stover says, but miners also extracted tungsten, copper and zinc. They started in the late 1860s, before Colorado was even a state and more than a century before Colorado had any laws about mine reclamation.

“In Boulder County, there’s mostly the physical hazards,” Stover says. “You can be walking along, and either the ground gives way, or the stope has breached the surface and it’s open. A lot of those that we found would be hundreds and hundreds of feet deep.”

Open shafts, portals and stope openings, where a miner followed an ore vein upwards and mined it all the way to the surface, are occasionally unmarked. There have been reports of pets falling into these shafts.

The survey is progressing, and Stover says the sites they’ve surveyed this year should be secured by the end of 2012. But the process is an ongoing one.

“You’ll never get them all because you just don’t know where they all are,” he says.

Historically, Colorado law did not require miners to close shafts or clean up pollutants after ceasing operations, which has left the hillsides near Fourmile Canyon spotted with a few orange tailings piles.

“Water can run through these old mine shafts or run over and through tailings, [and] that can contribute to some water quality problems,” says Susan Martino, an environmental health specialist with Boulder County Public Health.

She participated in the initial survey of the burned area for the Burned Area Report.

“Mostly what we found was the impact from the mine and the mine waste tailings was going to be low to moderate as far as impact to the water quality,” she says.

Mining debris, particularly in sites like Ingram Gulch, where there is mine debris in the drainage, could affect water quality if a heavy rain started to move the waste and debris down the drainage. The aerial mulching is expected to help prevent those build-ups of debris and sediment.

“A lot of these sites actually have pretty hard crust on them,” Martino says, which makes them less likely to erode.

But with vegetation gone and erosion expected to increase, it’s unclear how much that hard crust will hold up.

Downstream, the community of Pine Brook Hills draws its water from Fourmile Creek. Bob de Haas, manager of the Pine Brook Water District, also applied for and received a grant from the state to alleviate concerns with the possible changes in water from Fourmile Creek.

“One of the big specific areas is the total organic carbons in the area,” de Haas says. (Organic carbons are burnt plant matter.)

“When you treat that water with the type of system we have, it doesn’t remove the soluable organic carbons. Then when we disinfect the water, it can create what we call disinfection byproducts,” he says. “If these byproducts are too high and you’re exposed to them for a long time — many, many years — then it may increase the odds that you would get cancer.”

He’s spent $64,491 of the $192,000 grant the district received so far to add parts to the filtration system to change the treatment process and will spend another $80,000 to pay for a treatment system that will assist in removing the plant matter. He’s also installed aerators to help oxidize metals to bring them out of the water, and plans to continue monitoring the quality to see if an issue arises with heavy metals.

“That one is the hardest one to really nail down as to how much will we or won’t we see,” he says. “So far, we’re not seeing anything that really indicates that that is an issue yet.”

This spring’s wet weather may actually be helping. “There’s more fresh water being mixed with it, so it’s keeping the levels down, but at the same time it’s steadily washing that stuff away. So we’re not seeing a big increase in concentration so far, because there’s a lot of water flowing down there right now,” he says. “We’re all sort of crossing our fingers and watching.”

Water collected from the creek is added to a reservoir, which also helps dilute any metal-heavy water.

The concern is a big thunderstorm.

“You get a big flood over there, and who knows [about the] damages and how it’s going to change things,” he says.

He has the option of shutting off intakes from the stream and relying on the reservoir if the stream water reaches unacceptable levels of contamination. Raw water is tested weekly, or twice weekly during rainy weather.

The Pine Brook is not the only water district in Boulder County dealing with heavy metals in the water.

Boulder County’s mining history has put the Left Hand Water District downstream from a Superfund site, the Captain Jack Mill. In the early ’90s, the creek ran milky gray about six miles downstream from the site, and sampling found high levels of zinc, cadmium, copper and lead, according to an Environmental Protection Agency report. The Left Hand Water District shut off its drinking water intake 15 miles downstream of the site, and the Colorado Department of Minerals and Geology filed a restraining order to stop operations at the mill. A task force was formed to evaluate the mines in the area, resulting in establishment of the Left Hand Watershed Oversight Group, which continues to monitor the water quality.

“It was just a cumulative sort of issue, recognizing the issues and, of course, the major player was also the Left Hand Water District, the drinking water provider that had some concerns about their source water,” says Mark Williams, water quality program coordinator for Boulder County Public Health, which was instrumental in organizing the task force that studied the abandoned mine issues facing Lefthand Creek. “For decades we’ve known that there have been impaired waters from the Lefthand.”

Zinc, copper, lead and cadmium are still present at measurable levels in Lefthand Creek and its tributary James Creek, but the input isn’t large enough to cause concern at the Left Hand Water District, says Joseph Ryan, a University of Colorado professor in the civil, environmental and architectural engineering department who focuses his research on what happens to contaminants when they get into natural waters. He has served as the technical advisor for the Lefthand Creek TAG (Technical Assistance Grant) Coalition.

“The big sources of contamination are on the order of 15 to 20 miles upstream of where Left Hand Water District has their intakes in Left Hand Creek, and any of the metals that are coming in from the mines are attenuated,” Ryan says. “They’re removed by the time they get that far downstream. So the risk to drinking water is really quite small.”

“We’ve never had poor water quality by the time it gets downstream to us,” says Kathy Peterson, general manager of the Left Hand Water District. “There’s no pressing concern. Those are long-inactive mining sites.”

With the initial assessment of the area and the resources available, the task force pursued both voluntary cleanups and Superfund status. But the Safe Drinking Water Act requires that even a voluntary or “good Samaritan” cleanup meet the standards for safe drinking water. To avoid being held responsible long term for meeting water quality standards, some voluntary projects focused on recontouring the land — “everything short of really trying to treat the water quality head on,” Williams says.

“Some of these other good efforts make the site more aesthetically pleasing, but the jury is still out on whether they actually help water quality,” he says.

Design for subsurface remediation at the Captain Jack site, where water is building up in a tunnel, is expected to be completed in 2012, according to the Colorado Department of Public Health and Environment.

The 2002 report from the task force required ongoing monitoring, which has occurred in the Lefthand Watershed Oversight Group. Glenn Patterson is coordinator of that group.

While the water is meeting drinking water quality standards — which are actually lower than the standards for aquatic life, according to Patterson — the upstream areas are still a hard environment for water organisms.

Water samples collected by the EPA have shown levels of aluminum, cadmium, copper, lead, manganese and zinc where the water from the Big 5 Adit, part of the Captain Jack Site, enters Lefthand Creek.

“The metals definitely impact fish and the invertebrate populations in the stream,” says Joy Jenkins, remedial project manager for the Superfund Remedial Program at the Environmental Protection Agency. Prior to joining the EPA, Jenkins was a consultant at Mine Water Treatment.

After a wildfire, movable minerals become a concern.

“From a general sense, you are concerned about transport of metal-laden sediments into the creek when you have that combination of a forest fire and then torrential flooding, which will wash particles down into the creek that may be metal-laden,” Jenkins says. “Then there will be physical transport of those metals downstream, which may or may not be an issue — it depends on the particular chemistry of the metals, whether they’re going to solubilize in the creek or not, or whether they would just sit at the creek bottom and cause the same sort of problems sediment does in general.”

Relatively low concentrations of copper can affect fish. Concentrations of lead can impact the invertebrate community. But what those impacts are depends on a particular situation, including what was mined and how it was mined. And because it’s hard to even know where the mines in this area are, identifying what the hazards are becomes even more difficult.

“There’s potential for the hazard to increase if you’re washing metal-laden sediments down, but it will depend on a lot of factors as to what the real risks to your stream communities are going to be,” Jenkins says.

“The typical afternoon thunderstorms, if it parks over one of these areas and dumps a lot of rain and we get a lot of erosion, that will definitely make a difference for Boulder Creek water quality,” Ryan says. “In some ways, that’s not a big deal because Boulder Creek water quality doesn’t affect water in Boulder.”

But private wells in the area may also see impacts.

“If there’s movement of sediment, shallow wells especially are easily contaminated by anything that occurs on the surface,” Williams says. “Even some of the 200-, 300-foot-deep wells, even in a typical spring you can see increased murkiness, turbidity, which indicates some quicker connection to what’s going on at the surface with the melting snow.”

While no reservoirs serving Boulder County have been directly impacted by the fires — the Fourmile Canyon Fire or any of the smaller fires last summer — much of Boulder County is at high risk for wildfire, Williams says.

Much of Writer and Murphy’s research is intended to provide information to help after future fires that might have more direct impacts on watersheds that feed into large municipalities.

For instance, the Track Fire burning this week is expected to affect the watershed for the town of Raton, N.M.

“If you look at a map of historic fires in Boulder County, it’s only a matter of time before your watershed will burn,” Murphy says.

The city of Boulder has been interested in their research, she says, because they want to know what to prepare for.

Boulder, Lefthand, Jamestown and Ward all share the same headwaters, so a fire in that one area could lead to water quality concerns throughout the county.

“I think wildland fire is becoming one of our key critical issues of concern,” he says. “Typically you worry about industry or other impacts. We’re fortunate that we have a pretty pristine watershed, but we still have the wildland/urban interface, and a lot of dead and dying forest. So yeah, it’s a big concern.”

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