Reservoir discharge exceeded state limits
The discharge from draining Grizzly Reservoir last month sent levels of aluminum and iron down the Roaring Fork River that acutely exceeded state standards for aquatic life, according to a report that analyzed samples taken by city of Aspen employees.
In addition, the discharge also potentially contained levels of copper and manganese higher than state standards, though that could not be determined for certain with the available data, according to the report by Lotic Hydrological in Carbondale.
But no evidence of acute effects, such as fish kills, were reported to government officials by residents or fishing guides who frequently work the river, and the discharge did not exceed human-health standards, the report states. The levels of copper and manganese did exceed agricultural standards, however.
Rick Lofaro, director of the Roaring Fork Conservancy, likened the discharge Tuesday to a bad sunburn, “but it’s not like you have skin cancer.” He said some damage may have occurred, but the river will heal itself and be OK in the end.
“It’s not good, but it’s not that bad,” Lofaro said. “The damage was fairly minimal.”
However, Andre Wille, a local high school chemistry teacher and longtime river-watcher, said the Grizzly discharge “was a lot worse than I had thought.”
Wille said he’s been part of River Watch Colorado, a program under the state Department of Parks and Wildlife, for 25 years, which has been taking samples from the river every month and having them analyzed. Wille also is chairman of the Pitkin County Healthy Rivers and Streams board.
“This is the single largest event with toxic chemicals coming down the Roaring Fork River in the last 25 years,” Wille said. “Never have we come close in 25 years to exceeding state standards.”
Officials from the Twin Lakes Reservoir and Canal Co., which runs Grizzly Reservoir, discovered a tree lodged in an outlet gate at the reservoir around Aug. 8, according to the report. Concerned that forecasted precipitation at the time might trigger a dam failure, those officials decided to drain the reservoir to fix the gate.
They drained most of the reservoir through tunnels heading east toward Denver, the report states. But they sent the remaining 10 to 20 acre-feet of water that remained at the bottom of the reservoir down Lincoln Creek and into the Roaring Fork River, according to the report.
That sediment-laden water turned the Roaring Fork River brown as it moved downstream during the early hours of Aug. 10, while “residual amounts of turbid water continued to move downstream (during) the next several days,” the report states.
Area residents quickly noticed the change in the usually clear-running river. City of Aspen officials collected samples Aug. 13 from the reservoir bottom, the outlet from the reservoir into Lincoln Creek and from the Roaring Fork River at Stillwater Bridge just east of Aspen, the report states.
The metals in the water “continually accumulate in the sediments of Grizzly Reservoir due to acid-mine drainage from the Ruby Mine site and natural acid-rock drainage from the highly mineralized geology in the mountainside above Ruby Mine,” the report notes.
Ruby Mine is located on Lincoln Creek about 4 miles upstream from the reservoir.
Grizzly Reservoir officials did not tell anyone downstream they were draining the reservoir.
“Had we known what was going on, this community would have reacted sooner,” Lofaro said. “I think they should have given us some heads-up.”
But as it was, samples didn’t get taken until three days after the initial pulse of Grizzly drainage flowed down the river and through Aspen.
“It’s safe to assume there were probably larger amounts of these metals (flowing down the river before the samples were taken),” Lofaro said.
Still, he doesn’t think Grizzly officials had malicious intentions when they drained the water because they felt they were facing an emergency situation. He is talking with those officials to make sure such an event doesn’t happen again without the knowledge of the community.
And Lofaro said what they did is not considered a violation, and he doesn’t expect state water-quality officials to become involved in the situation.
“I don’t want to say it’s no problem, but it was a small enough event,” Lofaro said. “Rivers are resilient.”
A message left Tuesday at the Twin Lakes Resevoir was not returned.
The report states that “it is likely and hopeful that the short duration of the event and dilution of the metal-impacted water by tributaries as it moved downstream will not produce long-term effects.”
However, the gate draining the reservoir into Lincoln Creek and the Roaring Fork River is still open because the broken gate has not yet been fixed, Lofaro said.
Wille, though, called the discharge “a pretty significant event.” He pointed out that iron levels measured at the Grizzly outlet three days after the discharge were 13 times the state standards, while those at Stillwater were three times the state levels.
“The Upper Roaring Fork has never seen levels like that,” Wille said. “If any industry would have floated that kind of pollution down the river, there would be consequences.”
Wille said he hopes there are no long-term effects from the discharge, though iron can coat the bottom of the river and smother trout eggs and other organisms.
“Hopefully it will get washed through,” he said. “But I just don’t want to downplay this. This kind of thing can’t happen in the future. The Roaring Fork is a pristine river.”
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