Dredging up the past
After decades of gravel mining, stretch of Animas River eyed for restoration
The Animas River has had its issues – contamination from the Silverton area’s mining legacy, chronically lower flows because of a 20-year drought, the septic pond at Lightner Creek Mobile Home Park leaching poop into the river, to name a few.
But one of the less commonly discussed, yet perhaps among the most significant issues, is the impact of historic gravel mining on the 6-mile stretch from Bakers Bridge to Trimble Lane, north of Durango. Over the years, gravel mining has completely altered the function of the river and turned it into what looks like the surface of the moon.
“I think this section of river ought to be top priority,” Peter Butler, co-founder of the disbanded Animas River Stakeholders Group and longtime Animas River advocate, said. “It is the stretch of river that’s most disturbed and has the most degraded habitat.”
Indeed, much attention has been given to restoring the Animas River over the years, including, most notably, the Environmental Protection Agency’s Superfund that was declared in the wake of the 2015 Gold King Mine spill to clean up the mines around Silverton.
Yet the damage left by gravel mining between Bakers Bridge and Trimble has gone largely unnoticed and unaddressed – in part, because that stretch, hemmed in by private property, is relatively unused for recreational purposes such as river running or fishing.
But that all might soon change. Recently, a number of stakeholders invested in the Animas River began the process of forming a stream management plan (SMP) for the waterway, which will likely address lasting impacts caused by historic gravel mining.
“It’ll be in there,” Warren Rider, coordinator of the Animas Watershed Partnership, which is leading the SMP process, said. “Too many people are justifiably concerned about how the river is behaving in that area and the consequences of it. It was eye-opening when I first saw what the impacts have been.”
As the Animas River tumbles and crashes at a high gradient from Silverton through the San Juan Mountains, it spills out sediment and alluvium into the first flat area it reaches: the floodplain below Bakers Bridge.
As such, mining companies early on realized it was a prime area for valuable materials. The first attempt was for gold. Local historian Charles DiFerdinando said that in the 1950-60s, large equipment was placed in the river to dredge for gold.
But ultimately, that venture failed, DiFerdinando said. Instead, companies started to notice the vast amounts of gravel that had been deposited over thousands of years. That set off decades of companies excavating gravel and sand from the river bed, leaving behind a mangled river.
“Those companies greatly altered the river up there, and disturbed sediment and fish habitat,” DiFerdinando said. “But in earlier days, they didn’t care about that.”
Dan James, of the James Ranch – situated within the Animas River Valley – said his family complained for years about the impacts of gravel mining. After companies dredged, the river would cut into the banks and cause significant erosion in areas that previously were stable. James estimated that every year, his family would lose an acre or two from erosion and bank incision. And, James said the groundwater table was so affected that perennially wet springs on the property started to run dry.
The problem at the time was that the Army Corps of Engineers (which oversees gravel mining in rivers) wasn’t particularly concerned with the issues caused by gravel mining, James said. The gravel companies, too, argued the alluvium was replenished every spring with runoff.
But the Jameses and others knew that at the rate gravel was dredged, there was no way the river could bring down that amount of sediment year after year. Instead, the companies dug deeper and deeper into the Animas River. So, in the 2000s, the Jameses pushed to have the gravel companies track their impacts, which the Army Corps of Engineers did require as a part of the companies’ permits.
“The evidence indicated, yes, the gravel companies were impacting the river,” James said. “They tried some techniques (to better mine gravel), but that failed. So when their permits expired, that was that; we haven’t seen them in the river since.”
A call to the Army Corps of Engineers was not returned.
Off with their heads
Gravel mining completely ceased in the north Animas Valley around 2008-09, but its impacts remain. For those who float the section, the scars are easily seen, evidenced by large, concrete boulders used to try to stabilize the bank and a shockingly braided river channel.
One big issue is something known as headcutting, which is when erosion occurs at a point in the river, causing the channel to deepen and cut away upstream. As a result, headcutting can lead to rapid erosion and deepening of streams, destabilizing the surrounding stream banks and potentially causing flooding downstream. It can also contribute sediment into the river, harming aquatic habitat and water quality.
In the section from Bakers Bridge to Trimble, Butler said the river channel is incredibly unstable, and is known to flow erratically and with more intensity. In the 1990s, for instance, the river channel shifted 200 yards across from its natural channel – overnight.
“Of course, it was much closer to some people’s houses than it was the day before,” he said.
Though there are populations of brown trout and sculpin, because of the nature of the flow and intense sediment loading, that stretch likely never had a robust aquatic life, Jim White, an aquatic biologist for Colorado Parks and Wildlife, said. But gravel mining exacerbated the problem.
“I’m sure the riparian habitat was in much better shape prior to those disturbances,” White said.
Scott Roberts, an aquatic ecologist with Mountain Studies Institute, said all of these issues – bank instability, incision of the channel, headcutting, the erosion of people’s property – add up. Even head gates for ditch companies are at risk.
“I do think it’s a high priority (area to be addressed),” Roberts said. “It has a lot of cascading effects along the river … and a lot of people are concerned about it.”
Go with the flow
Thankfully, help could be on the way. In 2015, the State of Colorado adopted the “Colorado Water Plan,” which calls for 80% of river basins across the state to have SMPs by 2030. That effort started locally last year and remains in the early stages.
Rider, though, said the Bakers Bridge to Trimble stretch has been identified as a place for possible restoration. Some people, he said, have expressed that it’s one of the most important issues to address from an environmental standpoint on the river.
“The river (in that stretch) is not functioning the way it should,” he said. “So you can either let it reestablish itself over a millennia, which it’ll do, or we can get in there and try to speed up the process and reproduce habitat and functionality.”
What that looks like remains to be seen, but there are examples in other watersheds.
On the San Miguel River, just downstream of Telluride, a restoration project reestablished the river’s natural course after it was graded for a now-defunct railroad line. Beforehand, the river was a channelized straight shot that eroded its banks and was disconnected from its floodplain.
“They returned the river to its original, meandering course through a floodplain with big pools,” Roberts said. “It’s so cool; trout habitat improved substantially, and it’s a neat example of restoration. It’s not the same problems as we see on the Animas, but as far as the scale and scope, there are some similarities.”
Nature, too, is doing its thing, James said. Ever since the gravel companies stopped dredging, little by little, the river is returning to its natural course.
“I’m hopeful the river can heal that wound,” James said.