From The Greeley Tribune (Catharine Sweeney):
Johnstown water officials are under investigation for inadvertently killing almost 1,000 fish in the town’s reservoir this summer.
In an effort to treat an algae outbreak, a worker put a chemical compound into the water that ended up suffocating 972 fish, Jennifer Churchill, a spokeswoman for Colorado Parks and Wildlife, said on Thursday.
On July 29, the employee applied 40 pounds of copper sulfate — often used as a pesticide — to the reservoir.
“That has been used in the past with no issues,” she said.
That wasn’t the case this time.
Several days later, hundreds of dead fish washed ashore. Officials instructed the Johnstown Police Department’s animal control division to clean the mess, and then reported the incident to the division of wildlife, Churchill said.
The reservoir, which is north of Colo. 60 and east of High Plains Boulevard, is used for the town’s drinking water and recreational fishing. Officials didn’t express any concern about public health as a result of the chemical in the water. Higher concentrations can cause nausea. The compound can cause eye irritation, but swimming isn’t allowed in the reservoir.
Colorado Parks and Wildlife officials got involved because the agency supplies the fish for the lake, as it does for many fishing ponds across the state.
“When we have fish killed, it’s not uncommon for there to be reimbursement for the fish,” Churchill said.
As of today, Churchill said officials aren’t considering criminal charges or fines.
“We’re hopeful that we can get it resolved without any kind of litigation,” said Johnstown Town Attorney Avi Rocklin.
Officials didn’t notify residents of the kill on its website or Facebook page.
“There was talk about putting something out there, but I can’t tell you whether that was done or not,” Rocklin said.
It also hasn’t been on any town council meeting agendas for public discussion.
“Obviously, we’re still in the middle of an investigation,” she said. “It may be premature to be having conversations about it.”
Copper sulfate-caused fish kills aren’t unique, according to a fact sheet from the National Pesticide Information Center.
However, the chemical doesn’t poison them. Sudden plant death and decomposition depletes the lake’s oxygen, and dead plants can clog gills.
Neither Greeley’s water department nor the Northern Water Conservancy District use the compound.
Greeley supplies water to its residents as well as Evans and parts of Windsor. Northern Water administers the Colorado Big-Thompson project supplies water to about 900,000 people in northern Colorado.
Although Greeley might use the compound in park ponds, it doesn’t go into Greeley’s drinking water, said Water and Sewer Director Burt Knight.
Instead, Greeley uses a carbon-based compound to eliminate algae, odor, and tastes, he said.
Northern Water used to use copper sulfate on reservoirs to control algae and aquatic weeds, said Water Quality Engineer Judy Billica,but it stopped in 2008.
“Copper, (even) at very low concentrations, can impact aquatic life, including fish,” she said.