Electric Fishwrap has moved

Reservoir’s fish exceeded safe level

By Kate Martin

Reporter-Herald Staff Writer

Last November, Harry Rosenhagen was about to pull his fishing boat out of Horsetooth Reservoir for the last time of the season.

Instead, he turned his 16-foot tri-hull boat back onto the waters. He said he wanted to burn off the remaining gas in the tank of his small outboard motor.

Fishing served a dual purpose, and he soon found himself trolling the quiet depths.

An hour later, he hit a snag.

But snags don’t pull a boat sideways. It was a wiper, and a big one.

“They put up a real battle,” said Rosenhagen. “They turn sideways. You’ve got to wait until they tire out.”

Twenty minutes later, Rosenhagen pulled in a large, silvery striped fish.

The wiper — a cross between a striped bass and a white bass — weighed in at 10 pounds and measured 27 inches from nose to tail.

“It was the biggest one I’ve ever seen, and I ate it.” he said. “It was delicious.”

But in January, a fish consumption advisory gave him pause. There’s mercury in the fish at Horsetooth Reservoir, in concentrations higher than 0.5 parts per million. Warnings say most people should only have one serving of wiper per month.

“If it’s bad enough where you can only eat it once or twice a month, you probably shouldn’t eat it at all,” Rosenhagen said.

The Colorado Department of Health and Environment started testing lakes for mercury about a year and a half ago. Testing on this wide a scale has never been done before, said Mark Salley, a spokesman for the department. Results for other lakes in the area — Carter Lake, Boyd Lake and Horseshoe Lake — will be in within the next several weeks.

Salley said there’s no cause for great alarm.

“Fishing is still a great sport. There are still plenty of edible fish,” he said. “If they’re not on the list then they’re edible.”

Rosenhagen, 73, said he’s not sure whether to renew his Larimer County parks pass for the boat and his car, a combined cost of $100.

“The same pass is good for Carter as it is for Horsetooth,” he said, “but I don’t want to buy a pass just for Carter.”

He said he will wait until the mercury testing results come back from Carter Lake’s fish.

Rosenhagen also plans to attend a public meeting Wednesday that addresses the mercury warnings, at 6:30 p.m. in the Fort Collins city hall, 300 LaPorte Ave.

The state health department and the Colorado Division of Wildlife will host the meeting. Experts in biology, surface and drinking water, wildlife, epidemiology and air quality will answer questions.

What is mercury? Mercury is a shiny, silver-white metal that is liquid at room temperature. At room temperature, exposed elemental mercury can evaporate to become an invisible, odorless toxic vapor. Mercury is used in thermometers, fluorescent light bulbs and some electrical switches.

How does mercury get into fish? Mercury in the air eventually settles into water or onto land where it can be washed into water. Once deposited, certain microorganisms can change it into methylmercury, a highly toxic form that builds up in fish, shellfish and animals that eat fish. Fish and shellfish are the main sources of methylmercury exposure to humans.

What can mercury do to humans? Mercury exposure at high levels can harm the brain, heart, kidneys, lungs, and immune system of people of all ages. It has been demonstrated that high levels of methylmercury in the bloodstream of unborn babies and young children may harm the developing nervous system, making the child less able to think and learn.

— Environmental Protection Agency

Originally published March 27, 2007.