Balancing the three R's (regulation, research, and restoration) on the Kenai River, Alaska

Abstract

in the world are linked to the following unique features:(1) The river has sustained high flows for extended periods of time providing salmon adequate periods to spawn and migrate in the river.(2) Two large lakes along the river, Kenai and Skilak Lakes, regulate streamflow variations, reduce sediment movement, and provide salmon with rearing and overwintering habitat.(3) Much of the Kenai River channel is stable, which helps maintain adequate spawning and rearing sites. (4) Historically, development in the river's watershed has been sparse and sources of water pollution have been few. Fair Regulation and Proper Restoration Depend on Sound ResearchSalmon return and harvest numbers have been increasing in recent years. However, regulations restrict development in the river's flood plain and close other Kenai River watershed (green area) and U.S. Geological Survey stream-gaging stations (red dots) in Soldotna and Cooper Landing ALASKA Map area Sterling areas to fishing. Many damaged streamside areas on the river are being restored, yet little monitoring of the performance of these restoration projects or research towards improving restoration designs has been accomplished. The role of the U.S. Geological Survey and other Federal and State agencies is to complete high-quality scientific research to help develop fair regulations and proper restoration designs for the preservation of the Kenai River fisheries.

Geologic studies in Alaska by the U.S. Geological Survey, 1996

“…On the Kenai River, this washing away of accumulated fine-grained sediment occurs only when streamflow is great enough to erode the armored bed material. During a large flood in Septemberl995, which has an estimated recurrence interval of 100 years, the streambed was eroded as much as 1.5 m at the stream-gaging station in Soldotna (Dorava, 1996). In comparison, during the 10-year period between 1980-90, less than 0.5 m of total erosion occurred at this site.…”

“…The influence of glaciers on the hydraulic characteristics near streamside structures along the Kenai River has been described by Dorava (1995). The potential links between salmon productivity and several unique glacier features of the Kenai River have been described by Dorava and Liepitz (1996). The influence of glaciers on river morphology and streambank erosion along the Kenai River is described by Scott (1982).…”

“…The 152 three most important habitat attributes for rearing juvenile chinook salmon are abundant streamside and instream cover, navigable water velocities, and appropriately sized substrate (Estes and Kuntz, 1986;Liepitz, 1994). Recent studies that pertain to salmon habitat in the Kenai River include those of Reger and others (1996; Quaternary deposits), Scott (1982; erosion and sedimentation), Dorava (1995; hydraulic characteristics near streamside structures), Dorava (1996; effects of flooding); and Dorava and Moore (1997; effects of boatwakes on streambank erosion). Results of these studies illustrate the relation between the quality of aquatic habitat and the past and present influence of glaciers in the Kenai River watershed.…”

“…Several studies by the U.S. Geological Survey (Dorava, 1995;Dorava and Liepitz, 1996;Karlstrom, 1964;Post and Mayo, 1971;Scott, 1982) have identified specific geomorphic, hydrologic, and aquatic-habitat features of the Kenai River that have been derived primarily from glaciers, which are or were within the watershed. This report discusses the roles of glaciers in the watershed as they relate to chinook salmon habitat.…”

Effects of boatwakes on streambank erosion Kenai River, Alaska

“…Thus, for years with extreme flooding, the relation of tractive energy to wake energy may be significantly different from that for the low-flow year of 1996. Additionally, bank erosion measured as a result of the 1995 flood was more than 20 feet in a streamside subdivision near Beaver Creek and more than 8 feet in an undeveloped segment of the river upstream from Kenai Keys (Dorava, 1996).…”