Animas River fish populations were already on the decline when an estimated 3 million gallons of mine runoff contaminated its waters earlier this month. Now, wildlife officials are trying to determine if the Gold King Mine spill further exacerbated a decades-old problem.
This week, aquatic specialists for Colorado Parks and Wildlife have been conducting a river survey – from Cundiff Park to the walking bridge behind the La Plata County Fairgrounds – to better understand the Aug. 5 spill’s impact on fish populations.
“We did it last year, and we normally skip a year,” Parks and Wildlife spokesman Joe Lewandowski said. “But because of the spill, our biologists decided it’d be a good time to do it again and see what’s going on.”
Essentially, crews place electric probes in the river to stun fish, which are then scooped up, marked, weighed and released. Wildlife officials will make another pass of the same section to compare the marked and unmarked fish, giving them an idea of the population trends.
“There’s just a lot of community interest now of how the spill might affect the fish population,” aquatic biologist Jim White said.
Although the survey began Monday, White said specialists were already getting an idea that fish in the Animas were not wiped out by the orange plume. Instead, numbers reflect the continuing downturn of the river’s fish.
“It’s similar to last year, which is not good,” White said.
For the past 10 years, fish populations in the Animas have been on a steady decline. White said a number of factors, including less water in the river, urban runoff and higher water temperatures, are to blame.
Ty Churchwell, Animas River coordinator for Trout Unlimited, said heavy metals in the water are a component of fish decline but are not the “smoking gun” most people think it is. He said pH levels in the water during the spill never reached a measure that would have made the metals devastatingly toxic.
“We are grateful there was not a mass die-off of trout when the plume came through,” he said. “But the Animas has been impacted and impaired by heavy metals for decades. That was a really big flush of water ... but we think long-term exposure is far more detrimental than short-term exposure.”
Further up in the Silverton Caldera, Cement Creek flows as a toxic, inhabitable stream, fueled by a history of unregulated mining practices. Wildlife experts have said they never expect the creek to be hospitable to aquatic life, but more optimism has been directed at the flow waters beneath where Cement and the Animas meet.
Fish populations there did rebound in the 1990s when stakeholders of the mine installed treatment plants that improved water quality. But in 2004, state and federal agencies, along with owners of the mine, decided to plug the mine and shut down the water-treatment facility.
About 25 miles downstream from Silverton, the presence of trout all but disappeared, with 3 out of 4 species now gone. It is there where state wildlife officials will go in the next couple of weeks to test waters to see if any fish remain in the wake of the spill.
“The moral of the story is: We’ve had water-quality issues in the Animas for a very long time,” White said. “We’ve seen signs of that upstream, where fish are truly affected by the metals. The goal is for mitigation in the Silverton area. Any bit of improvement in Silverton helps.”
Luckily for business owners who rely on the Animas for fishing and tourism, by the time waters reach downtown Durango, metal concentrations are diluted enough that recreation on the river is deemed safe.
Kyle Hartley, manager at Duranglers fly-fishing shop, said the number of people coming into the store died pretty fast after the spill, but in the weeks since, tourism has rebounded.
“The river’s fishing great for us right now,” he said.
Hartley said the Animas accounts for a small percentage of the trips the store offers, mostly because the fishery has been in poor health for such a long time, but also because of the plentiful options in the area.
“We’re lucky everything around us is so great, and we can go other places,” he said. “But we always tell people do not eat the fish (out of the Animas). Its been polluted forever.”
The Animas will continue to be studied by a variety of local, federal and state agencies as more information is gathered in the aftermath of the spill. Lewandowski said the test results on the 108 fish that were placed in the river, only one of which died, should be available next week.