Juvenile salmon once darted back and forth between the placid waters of Tern Lake and the meandering waters of Dave’s Creek, using both to find food and shelter. But construction on the adjacent Sterling Highway in the 1950s turned Dave’s Creek into a one-way street for juvenile salmon.
To make way for the highway, construction crews altered the flow of the creek’s water with three small dams and routed part of the creek through a ditch alongside the highway. After the changes, juvenile salmon could swim the creek downstream, but the dams prevented them from swimming upstream back to the lake. Additionally, the creek’s straightened path along the highway accelerated water-flow velocity, which inhibited juvenile upstream migration.
“They can only swim hard for short bursts and if you have a really long area of fast water, they have nowhere to rest,” said Jennifer McCard, a watershed scientist with the Kenai Watershed Forum.
“A normal stream has lots of twists and turns and meanders and nice overhanging banks that provide shelter.”
Thanks to federal stimulus money and a Kenai Watershed Forum grant proposal, projects removing juvenile salmon barriers to Tern Lake and similar barriers faced by other juvenile salmon on the Kenai Peninsula will receive a major boost.
On June 30, the National Oceanic and Atmospheric Administration awarded the watershed forum a $1.5 million grant to help restore salmon habitat. The grant is the largest the watershed forum has ever received, and was awarded as part of $167 million in American Recovery and Reinvestment Act money being distributed to help restore coastal habitat and the economy. Out of 814 proposed projects, the watershed forum restoration proposal was one of just 50 selected recipients.
The grant money awarded to the Watershed Forum will be used to restore degraded salmon habitat along Dave’s Creek, the Anchor River and to replace three culverts blocking salmon access to habitat in other streams on the peninsula. Dave’s Creek and the Anchor River provide habitat to king, coho and sockeye salmon, and other nonsalmon fish species. The Anchor also provides habitat to pink salmon and drains water from 224 square miles of watershed.
The Anchor River, like Dave’s Creek, has been degraded by human activity. In the 1990s a gravel pit was built within 100 feet of the Anchor River. Levies had been built between the river and the pit, but when flooding pushed the river over its banks in 2002, the river sloshed into the pit, changing its course and altering the riverbed.
“(The gravel pit) became the lowest point when the river flooded and it was easiest for the river to go through there,” McCard said. “It just sort of fragmented the river, because some of the levies were breached, some weren’t. So you have all of these strange islands and the river’s just completely fragmented.”
The river’s new course also accelerated the river’s water velocity and fine silts in and around the pit leached into the river. The silting has been exacerbated by the crumbling levies, muddying the water flowing through the pit and disrupting spawning downstream.
“Those levies are continually calving off like a glacier and falling into the river whenever there’s high water, and it’s a major disruption,” said Robert Ruffner, executive director of the Kenai Watershed Forum. “It muddies up the water and it’s introducing fine material into an area where we know salmon spawn, and we know salmon spawn right below this thing.”
The restoration project will, to the greatest extent possible, restore the gravel pit and levies to the original floodplain level and return the river to its original stream bed. But the river’s course has changed so dramatically that some of it will likely continue to flow through the gravel pit area even after restoration. To restore the gravel pit area back to its original floodplain level, the restoration project will fill the pit and level off the levies. The river has already begun some of the work, as it has deposited new materials into the pit.
At Dave’s Creek, the restoration project will remove obstacles inhibiting fish passage and help re-create the original meandering stream channel. Some restoration of Dave’s Creek has already been started, and its completion will be supported by the Watershed Forum grant.
Restoration work at Dave’s Creek and the Anchor River will be confined to between May 15 and July 15, when it will disrupt juvenile salmon and returning adult salmon the least. Once the projects are complete, Watershed Forum scientists hope salmon will thrive in the streams better than before.
“That’s our goal in restoring these places is to see if we can get better salmon populations,” McCard said. “I can’t say the salmon populations are low just because of a particular bad culvert, but it’s definitely one of the factors strongly influencing our salmon populations, and when you combine all of these different things that are going wrong, you’ll get a lower population.”