The Little Susitna River—An ecological assessment. Final Report for the Alaska Department of Environmental Conservation
Dates
Year
2007
Citation
Davis, Jeffrey C., and Davis, Gay A., 2007, The Little Susitna River—An ecological assessment. Final Report for the Alaska Department of Environmental Conservation: Aquatic Restoration and Research Institute: Talkeetna, AK, v. ACWA 07-11, 28 plus appendices-28 plus appendices.
Summary
Summary The Little Susitna River is an important recreational resource within south-central Alaska. The river supports five species of salmon and very popular Chinook and coho salmon fisheries. In 2004, 20,000 angler days were spent harvesting 45,000 coho, which is the second highest harvest level in south-central Alaska. Rapid increases in Matanuska-Susitna Borough populations and the river’s popularity have resulted in increased residential development and recreational use along the river. There is a potential for residential development and recreational use to cause a decrease in water quality and fish habitat. This study is the first step in characterizing the Little Susitna River from the Edgerton Road Bridge to below [...]
Summary
Summary The Little Susitna River is an important recreational resource within south-central Alaska. The river supports five species of salmon and very popular Chinook and coho salmon fisheries. In 2004, 20,000 angler days were spent harvesting 45,000 coho, which is the second highest harvest level in south-central Alaska. Rapid increases in Matanuska-Susitna Borough populations and the river’s popularity have resulted in increased residential development and recreational use along the river. There is a potential for residential development and recreational use to cause a decrease in water quality and fish habitat. This study is the first step in characterizing the Little Susitna River from the Edgerton Road Bridge to below the Public Use Site. Project objectives included, documenting the degree and cause of bank and riparian area modification, determining basic water chemistry including nutrient concentrations, fecal coliform bacteria, and petroleum hydrocarbons, obtaining measures of fish and macroinvertebrate community composition, and the physical channel characteristics from Edgerton Park Road to the Public Use Site. Bank and riparian modification was measured from 2004 aerial photography. Approximately 1% of the bank and riparian habitat has been modified from the Edgerton Road Bridge to the Susitna Lodge at river mile 15. Between Edgerton Park Road and Schrock Road, bank and riparian modifications increase to approximately 3%. The dominant cause of bank and riparian modification is residential development, followed by land clearing for agriculture, and roads. Stream water turbidity, fecal coliform bacteria, and water temperatures exceeded State Standards from water samples collected below the Public Use Site. However, these evaluations are based upon limited measures and require further confirmation. The river segment between the Edgerton Park Bridge and Cook Inlet can be divided into three distinct reaches that vary in channel slope, sinuosity, substrate particle size, and riparian vegetation. The biotic community reflected good water quality and habitat, with juvenile salmon abundant throughout. The bank and riparian areas along the Little Susitna River are largely unmodified. Most of the modifications have occurred due to residential development of the river between Schrock Road and Edgerton Park Road. This stream reach also contained the largest number of juvenile salmonids. None of the stream characteristics within this upper reach indicated any water quality or fish habitat problems; however, sampling was minimal. There was an increase in fine sediment and bed particle embeddedness below the Miller’s Reach launch suggesting increased bank erosion. There also appeared to be an increase in point bar formation within this area. Turbidity increased below the public use boat launch in June, which coincided with increased boat traffic during the Chinook sport fishery. Stream temperatures and fecal coliform bacteria were higher below the public use site than other locations; however, there was no consistent indication of volatile organic carbons, and juvenile salmon were abundant. As this was the first phase of the characterization of the Little Susitna River, additional information is necessary to support these initial findings.
