State to conduct additional turbidity monitoring this summer

The state will take extra measurements this summer to check whether the Kenai River really does exceed turbidity standards.

Turbidity — the measure of how much light reaches down below the surface of the water, based on how many suspended solids are in the water — came up as a problem for the Kenai River in the Alaska Department of Environmental Conservation’s most recent draft Integrated Report on the health of the state’s waterways.

Based on data collected by the Kenai Watershed Forum from 2008–2010, the DEC wrote in the draft report released in December that the Kenai River should be classified as an impaired water body for turbidity below about river mile 7.5.

The section of the river that exceeded turbidity standards only did so for a total of about 18 days in July during the three years of measurements. The report links it directly to motor boat traffic, which stirs up sediment from the riverbed into the water.

The finding has stirred controversy among river users, particularly sport fishing guides, who rely on motorized boats to navigate the river with clients. Many have said the data, which is now a decade old, is irrelevant because motor restrictions on the river have since changed and river traffic has moved away from being concentrated in that area.

The Kenai River Special Management Area Advisory Board, a citizens board providing management advice to the Alaska Division of Parks and Outdoor Recreation on Kenai River issues, sent a letter disagreeing with the turbidity finding based on user concerns.

The plan for this summer is to monitor the river with the same equipment in the same places for two weeks in July, said DEC program manager Nancy Sonafrank.

“We pretty much were calling it impaired. But it’s been a few years,” she said. “We can do a short confirmation study using the same sampling sites and the same kind of analysis.”

The confirmation study won’t be the same full-blown study the Kenai Watershed Forum did as a contractor for DEC in 2008-2010, but it will help check whether the same problem is still happening. If the same results come in, DEC will reaffirm its turbidity designation. If not, the department will “cross that bridge when we come to it,” she said.

The Kenai Watershed Forum will do the testing again during the two-week period in July this year, though they’re still working out the details with the state, said Executive Director Jack Sinclair.

“Personally, yes, I believe the boating traffic will have changed,” he said. “Eagle Rock (boat launch) didn’t exist as a public boat launch in 2010.”

DEC has been gathering public comment on December’s draft report before submitting it to the U.S. Environmental Protection Agency for approval before it goes to Congress, which has the final say on adopting the reports under the Clean Water Act. Sonafrank said the department expects to finish the report in September.

DEC hasn’t had an Integrated Report approved by the EPA and Congress since 2010. The latest one will include baseline water quality data from 2014-2016 but no new turbidity data since the 2008-2010 measurements.

At the same time as it is finishing its 2017 report, the state is working on its 2018 Integrated Report. Turbidity isn’t the only issue coming up in the data gathering for that study — baseline water quality sampling throughout the watershed, also coordinated by the Kenai Watershed Forum, is showing levels of zinc above the acceptable standard and rising levels of copper. Heavy metals like zinc and copper can be toxic in high enough concentrations.

The elevated levels are showing up in the urbanized part of the river, Sonafrank said. Other urban streams have shown similar issues, and studies have linked the presence of those two metals to stormwater runoff, she said. Zinc is present in galvanized metals, such as culverts, and copper is present in a variety of items, like brake pads on cars, she said.

“Zinc and copper are both used a lot in urban areas in daily life,” she said.

Reach Elizabeth Earl at

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