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USGS Alaska Water Science Center Publication

Water Quality of the Crescent River Basin, Lake Clark National Park and Preserve, Alaska, 2003-2004

By Timothy P. Brabets and Robert T. Ourso

Scientific Investigations Report 2006–5151

Prepared in Cooperation with the National Park Service


The U.S. Geological Survey and the National Park Service conducted a water-quality investigation of the Crescent River Basin in Lake Clark National Park and Preserve from May 2003 through September 2004. The Crescent River Basin was studied because it has a productive sockeye salmon run that is important to the Cook Inlet commercial fishing industry. Water-quality, biology, and limnology characteristics were assessed. Glacier-fed streams that flow into Crescent Lake transport suspended sediment that is trapped by the lake. Suspended sediment concentrations from the Lake Fork Crescent River (the outlet stream of Crescent Lake) were less than 10 milligrams per liter, indicating a high trapping efficiency of Crescent Lake. The North Fork Crescent River transports suspended sediment throughout its course and provides most of the suspended sediment to the main stem of the Crescent River downstream from the confluence of the Lake Fork Crescent River. Three locations on Crescent Lake were profiled during the summer of 2004. Turbidity profiles indicate sediment plumes within the water column at various times during the summer. Turbidity values are higher in June, reflecting the glacier-fed runoff into the lake. Lower values of turbidity in August and September indicate a decrease of suspended sediment entering Crescent Lake. The water type throughout the Crescent River Basin is calcium bicarbonate. Concentrations of nutrients, major ions, and dissolved organic carbon are low. Alkalinity concentrations are generally less than 20 milligrams per liter, indicating a low buffering capacity of these waters. Streambed sediments collected from three surface sites analyzed for trace elements indicated that copper concentrations at all sites were above proposed guidelines. However, copper concentrations are due to the local geology, not anthropogenic factors.

Zooplankton samples from Crescent Lake indicated the main taxa are Cyclops sp., a Copepod, and within that taxa were a relatively small number of ovigerous (egg-bearing) individuals. Cyclops sp. are one of the primary food sources for rearing sockeye salmon juveniles and were most prevalent in the July sampling. Qualitative-Multi-Habitat algae samples were collected from two surface-water sites. A total of 59 taxa were found and were comprised of 4 phyla: Rhodophyta (red algae), Cyanophyta (blue-green algae), Chlorophyta (green algae), and Chrysophyta (diatoms). Twenty-two algal taxa were collected from the upper site, North Fork Crescent River, whereas twice as many taxa were collected from the downstream site, Crescent River near the mouth.




Purpose and Scope

Previous Studies

Description of Study Area

Methods of Data Collection and Analysis


Water Quality of the Crescent River Basin

Streamflow, Suspended Sediment, and Turbidity

Water Temperature

Specific Conductance


Dissolved Oxygen


Major Ions, Dissolved Solids, Iron, and Manganese

Nutrients and Organic Carbon

Trace Elements in Streambed Sediments

Biology of the Crescent River Basin




Possible Effects of Logging on Water Quality.



Suggested Citation:

Brabets, T.P., Ourso, R.T., 2006, Water Quality of the Crescent River Basin, Lake Clark National Park and Preserve, Alaska, 2003-2004; U.S. Geological Survey Scientific Investigations Report 2006-5151.

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For more information about USGS activities in Alaska, visit the USGS Alaska Water Science Center home page.

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