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Is warmer water harming salmon survival in the famous Kenai River?

  • Author: Jenny Neyman
  • Updated: May 31, 2016
  • Published September 21, 2013

When a baby is sick it can't clearly communicate what's wrong. So an examiner looks for symptoms to make a diagnosis -- collecting samples, measuring temperature, looking at coloration and lethargy, and checking on past illnesses to see if there's been a flare-up. Environmental factors are noted, too. The patient is checked at the first sign of upset and monitored to see if the problem is endemic and worsening, or just a temporary disturbance.

So it is with the cherished Kenai River. The health of what many consider Alaska's premier sportfishing river is of vital importance to those who make their livelihood off it and the life nurtured around it. If the river and its extensive lineage of mountain glaciers, marshy wetlands and rain-draining tributaries suffer troubles, it can't express the problem in words. So scientists perform exams -- as any diligent doctor would -- measuring things like temperature, turbidity and pH, testing for toxins, and noting external conditions to gauge their possible impact on the water.

Since 1999 the Kenai Watershed Forum has conducted twice-yearly checkups on the river, not only to help diagnose and treat present problems, but to monitor overall conditions so that new issues can be caught early.

The latest checkup happened at the end of July, and results so far show a fair bill of health. The water continues to test low for hydrocarbons, a problem treated in 2008 with a switch from two-stroke to more efficient four-stroke boat motors on the lower river.

That doesn't mean the water was free and clear of crud, though. The Watershed Forum continued its testing for fecal coliform and enterococci bacteria at the north and south beaches at the mouth of the river this summer, and again found readings exceeding state water-quality levels. Much of the contamination is thought to come from a gull colony of some 50,000 birds that nests seasonally on the Kenai River Flats. So far in recent years' testing, though, that condition comes and goes on its own, much like a seasonal allergy. Other than warning the July dip-netters at the river mouth to conduct rigorous washing and food-safety practices when the bacteria levels test high, the Alaska Department of Environmental Conservation hasn't recommended any course of treatment.

Turbidity during times of high boat traffic continues to test high, a condition that hasn't been addressed. A study conducted by the Watershed Forum for the state Department of Environmental Conservation (DEC) in 2008, 2009 and 2010 noted spikes in the level of turbidity -- a measure of the amount of light scattering as it penetrates the water column, indicating the presence of solids suspended in the water -- correlating with times and areas of high motor boat traffic in July. The elevated turbidity readings surpass the allowed levels in all three DEC water quality categories -- drinking, recreation and fish and wildlife.

Though DEC's funding for the turbidity study ended in 2010, the Watershed Forum has continued to check turbidity levels with funding from the Kenai Peninsula Borough, and has continued to notice elevated turbidity coinciding with elevated boat traffic.

Meanwhile, the 2011 turbidity report, completed in 2012, remains with DEC. Though a local petition was submitted requesting that the river be listed on the federal impaired water body list, DEC has not recommended the EPA do so, nor has EPA stepped in to make its own determination.

DEC has said it isn't yet sure whether the turbidity is bad enough for a long-enough period to warrant such a step. An impaired listing would necessitate a plan for how to bring the waterway down to allowed levels, which could be complicated by the natural turbidity present in the river from its muddy tributaries and glacial-fed, silt-bearing lakes. Until a decision is made, watchful waiting is the prescription, with examiners continuing their checkups.

Another measure of overall health is temperature, and the Kenai seems to have run a bit of a fever this summer.

"We had four or five exceedances of the Alaska state water temperature standard of 15 degrees Celsius (59 degrees F)," said Branden Bornemann, water quality specialist with the Kenai Watershed Forum.

As it does with hydrocarbons and turbidity, DEC has standards for water temperature in various categories, depending on use of the water. Water for agriculture must not exceed 30 degrees Celsius. Water for drinking and culinary purposes may not exceed 15 C.

The standard for general aquaculture is 20 C (68 F), but lower for waters in which certain biological processes of fish life occur. For migration routes, such as salmon swimming upstream to spawn, and rearing areas, the maximum temperature may not exceed 15 C. For areas where spawning and egg and fry incubation occur, the temperature may not exceed 13 C (55.4F).

The Watershed Forum does its sampling every year in late spring and the end of July. Spring sampling does not produce unduly high water temperatures, as would stand to reason, given that ice and snow are generally still melting in late April. This year sampling was pushed back until early May 7, because the late, long breakup left ice blocking access to sampling sites in April. When spring testing was conducted, no temperature exceedances were found.

"Which would be expected, due to the winter breakup, essentially, ice being present in the river," Bornemann said.

Not so in July. Sampling at 22 sites on July 30 showed six sites in the mainstem of the Kenai and six tributary sites exceeding DEC water quality temperature standards. Samples at Kenai City Dock, Cunningham Park, Funny River, Morgan's Landing, Jim's Landing and Juneau Creek exceeded 13 C. And samples at No Name Creek, Beaver Creek, Moose River, Skilak Lake outflow, Russian River and the Kenai Lake Bridge exceeded 15 C.

At first blush, the sunny summer weather is an obvious culprit.

"We haven't speculated a lot but right off the top of everyone's head who spent the summer here would be the warm temperatures and lack of rain for the first half of the summer," Bornemann said.

While humans may revel in the sunny, warm summer temperatures of this year's June and July, aquatic life used to cooler temperatures does not. Sue Mauger, science director for Cook Inletkeeper, notes in her Stream Temperature Monitoring Network report the threats that rising temperatures pose in a fish-bearing watershed, yet the lack of data on the matter.

"High stream temperatures stress fish making them increasingly vulnerable to pollution, predation and disease," Mauger writes. Yet despite the links between warm water temperatures and reduced salmon survival in other regions, there is little consistent, long-term temperature data for salmon streams in Alaska, she adds.

"There is perhaps no greater indicator for gauging the health of wild salmon and their habitat than water temperature. Water temperature plays a critical role in all phases of the salmonid lifecycle, especially in freshwater systems. Stream temperature affects survivorship of eggs and fry, rate of respiration and metabolism, timing of migration, and availability of oxygen and nutrients.

"High water temperatures have been shown to induce physiological stress in salmon, which makes them more vulnerable to secondary stressors such as pollution, predation and disease."

The Stream Temperature Monitoring Network for Cook Inlet salmon streams has been an ongoing effort since 2008 to track water and air temperatures at 48 nonglacial streams around the region during the summer. The effort has shown that the Kenai is not alone in running a fever, nor is this year unusual. Every year has seen water temperatures above the DEC standards, even the relatively cool summer of 2012.

Mauger notes that of the 20 streams sampled on the Kenai Peninsula, all but two -- Resurrection Creek and Seldovia River -- consistently exceeded Alaska's water quality levels for the protection of fish. While that sounds alarming, there isn't enough data to know how significant it is. Maybe warm is just the norm on the Kenai? After all, as Mauger notes, historic water temperature data is lacking.

To get at that question, one part of the study is classifying the streams in terms of characteristics that could affect water temperature. For instance, the size of a stream and the clarity of the water affect temperature, as does groundwater influence, ground cover and development.

From those characteristics, some streams are classified as warm -- Bishop Creek, Hidden Creek, Moose River and Soldotna Creek, for instance; some as temperate -- Anchor River, Funny River, Deep Creek and Ninilchik River; and some as cool -- Resurrection creek and Seldovia River.

One goal of the project is to build a baseline of data to determine the normal parameters of a waterway, whether it tends to run cool or a little warmer, so that fluctuations can be noted in context of how common or uncommon the change might be. Another is to develop information on how streams' weather changes. Sunshine and air temperature have a significant influence on water temperature, but other factors can help "protect" a stream from heating up when the sun comes out.

"Water temperature can vary greatly across watersheds or even among tributaries within the same watershed, due to climatic drivers as well as structural factors like stream morphology, land cover, and groundwater influence. The goal of the Stream Temperature Monitoring Network for Cook Inlet Salmon Streams is to identify thermal impacts in coastal salmon habitat. Stream temperature data will be used to identify watershed characteristics that buffer stream temperatures, thus making them less susceptible to climate and land-use changes," Mauger writes.

Now that the project has gathered five years of data, the next step is to do this analysis.

"We are due this year to produce another summary report that would begin to analyze some of those trends more deeply and to kind of look at land-use patterns and climate patterns and even tidal patterns ... and see where some of these trends are occurring," Bornemann said. "The beauty of the project and, really, its principal goal, is to generate a baseline for space and time that we can then sit down and look at and see what kind of trends we're getting."

From that information, practical applications may follow.

"Alaska is thought to be experiencing the greatest regional warming of any state in the U.S., and warming patterns are expected to continue at least into the next century," Mauger writes. "… This project will play an important role in helping state and federal resource managers prioritize streams for research, restoration and protection efforts to ensure Alaska wild salmon endure as thermal change continues," Mauger writes.

Climate change is a topic of increasing interest in the scientific community, Bornemann said, and as with any scientific examination, having good data is the first step.

"It's on everybody's plate. The effects are really yet to be fully understood. We just see the trend and understand enough about climate to know that, yes, there could be very large impacts to fish runs, to fish habitat, to our quality of life here as far as drinking water is concerned.

"It's just like the river is intricately tied to all of our way of life here, so a warming river is again tied to our way of life here," he said.

Jenny Neyman is editor of the Redoubt Reporter that covers the Kenai Peninsula. Used with permission.

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