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Scientist samples Anchorage creeks for chemical that could be killing fish

Published: Sep. 17, 2021 at 4:20 PM AKDT
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ANCHORAGE, Alaska (KTUU) - When Anchorage Geochemist Birgit Hagedorn set out to sample Anchorage creeks for a chemical that could be killing salmon, she wasn’t sure what she’d find. Now Hagedorn has results, but perhaps not exactly what she expected.

The chemical, called 6PPD, is a compound found in tires. When it rains, the chemical leaches from roads untreated into storm drains, which empty into local creeks. A University of Washington study found even tiny amounts of 6PPD can be deadly to coho salmon. Hagedorn was concerned that an unexplained die-off of cohos in Anchorage’s Campbell Creek in 2017 and 2018 could be connected.

With help from a GoFundMe set up by the Anchorage Waterways Council, Hagedorn collected a total of 10 samples from Chester Creek and Ship Creek in both April and July. At $500 per sample, an outside lab analyzed and confirmed what Hagedorn called alarming levels of the chemical in storm drain water that runs into Chester Creek near the Seward Highway.

“We had concentrations above what we call the lethal limit for coho salmon,” she said.

The chemical was also found in the creek itself, but not at levels that are considered dangerous to fish, according to Hagedorn. At Ship Creek, the levels were even lower. Hagedorn said even though levels were diluted in the creeks themselves, the presence of the chemical surprised her.

“I was surprised that I found so much,” she said. “Because Anchorage doesn’t have a lot of traffic … so I was hoping we just don’t find anything, and then we are good to go.”

Hagedorn said her sampling was just a preliminary look. She thinks a lot more sampling needs to be done to determine if the chemical is really a problem in Anchorage creeks.

Cherie Northon with the Anchorage Waterways Council published the results on their website, and agrees. Northon hopes to find a funding source to continue the research, which Hagedorn said could be done locally at a lab at the University of Alaska Anchorage.

The Alaska Department of Environmental Conservation said via email it is also actively following the issue. A working group set up to discuss the problem plans to meet again this fall.

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