Effectiveness of streambank-stabilization techniques along the Kenai River, Alaska

Water-Resources Investigations Report 99-4156
Alaska Department of Environmental Conservation, Alaska Department of Fish and Game



The Kenai River in southcentral Alaska is the State's most popular sport fishery and an economically important salmon river that generates as much as $70 million annually. Boatwake-induced streambank erosion and the associated damage to riparian and riverine habitat present a potential threat to this fishery. Bank-stabilization techniques commonly in use along the Kenai River were selected for evaluation of their effectiveness at attenuating boatwakes and retarding streambank erosion. Spruce trees cabled to the bank and biodegradable man-made logs (called 'bio-logs') pinned to the bank were tested because they are commonly used techniques along the river. These two techniques were compared for their ability to reduce wake heights that strike the bank and to reduce erosion of bank material, as well as for the amount and quality of habitat they provide for juvenile chinook salmon. Additionally, an engineered bank-stabilization project was evaluated because this method of bank protection is being encouraged by managers of the river. During a test that included 20 controlled boat passes, the spruce trees and the bio-log provided a similar reduction in boatwake height and bank erosion; however, the spruce trees provided a greater amount of protective habitat than the bio-log. The engineered bank-stabilization project eroded less during nine boat passes and provided more protective cover than the adjacent unprotected natural bank. Features of the bank-stabilization techniques, such as tree limbs and willow plantings that extended into the water from the bank, attenuated the boatwakes, which helped reduce erosion. These features also provided protective cover to juvenile salmon.

Study Area

Publication type Report
Publication Subtype USGS Numbered Series
Title Effectiveness of streambank-stabilization techniques along the Kenai River, Alaska
Series title Water-Resources Investigations Report
Series number 99-4156
DOI 10.3133/wri994156
Year Published 1999
Language English
Publisher U.S. Geological Survey
Publisher location Anchorage, AK
Contributing office(s) Alaska Science Center
Description vi, 21 p. :ill., maps ;28 cm.; 10 illus.; 4 tables
First page 1
Last page 21
Country United States
State Alaska
Online Only (Y/N) N
Additional Online Files (Y/N) N
Google Analytic Metrics Metrics page
Additional publication details