For two decades, people have worked to preserve, study and rehabilitate the Kenai River to protect its salmon runs while the area's human population has soared.
But the river remains endangered.
People involved in river protection identify challenges human activities pose to the Kenai and its fish. Most threats are cumulative and arise from growing urbanization.
Hard surfaces: Pavement, gravel, buildings and even lawns are relatively waterproof compared with natural vegetation. Rain and snowmelt run off them directly into the river and its tributaries. The changes have physical and chemical effects. Runoff can increase erosion and decrease groundwater recharge. It can put oils, fertilizers, pesticides and other pollutants into the river before they can degrade.
Septic systems: Housing in unincorporated areas along the river (basically everywhere except Kenai and Soldotna) relies on septic systems or outhouses for sewage disposal. Systems that are old, faulty or too close to running water can introduce fecal bacteria, which cause illness and odors, into the river.
"We really don't know anything about how (septic systems) are working," said Phil North, who works for the federal Environmental Protection Agency at the Kenai River Center.
"We strongly suspect that is a problem. But we really haven't had a chance to look at it. ... It is not monitored."
Wetlands loss: The muskegs and lowlands along the river filter water going into it and provide food sources for fish. Wetlands are especially common along the built-up lower river.
North said people are becoming more aware of the wetlands' importance, but underestimate the amount of damage they can cause with small projects. They ask to put in a road here, a gravel pad there, and soon the projects add up to significant habitat loss.
Mary King, an Alaska Department of Fish and Game sport fish biologist researching habitat loss along the river, agreed that small disruptions can have big effects.
"The more we remove those (wetlands), then the more we are altering the ecosystem of the river. We don't know the sensitivity," she said.
Riverbank conditions: The area next to the riverbank is crucial rearing habitat for juvenile king salmon and other river organisms. Boat wakes erode the banks from below, and angler foot traffic pushes them down from above. Stabilization structures are still being evaluated to determine if they are effective.
"Some of the structures may or may not be fish-friendly," King said.
Culverts: Tributary streams pass through culverts under roads. Juvenile salmon have trouble swimming against the current through culverts. As fry forage in creeks, the culverts tend to funnel them one-way downstream, away from preferred habitat.
Robert Ruffner, director of the Kenai Watershed Forum, said, "They weren't designed right, and they haven't been maintained."
Water quality: The first cooperative agreements to monitor water quality were set up within the past two years. A consistent, long-term effort to watch the river for contaminants such as sewage, oil or glycol was lacking in the past. The future of the Soldotna Waste Water Treatment Plant and past incidents such as a dry-cleaning chemical contamination near the Soldotna bridge, salt in Soldotna Creek and PCBs in Kenai Lake have raised concerns.
Invasive species: Pike and perch have appeared in Kenai Peninsula lakes, apparently introduced by misguided anglers. People or flooding could move these predatory fish, which eat salmon fry, to the main river. Although such pests are unlikely to decimate salmon populations, they certainly would not help them.
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