USGS

 

Water Quality and Streamflow of the Indian River, Sitka, Alaska, 2001-02

By Edward G. Neal, Timothy P. Brabets, and Steven A. Frenzel

U.S. GEOLOGICAL SURVEY
Scientific Investigations Report 2004-5023

Prepared in cooperation with the National Park Service

This report is also available as a pdf.


Abstract

The Indian River Basin, located near Sitka Alaska, drains an area of 12.3 square miles. This watershed is an important natural resource of Sitka National Historic Park. At the present time, the watershed faces possible development on large tracts of private land upstream of the park that could affect the water quality of Indian River. Due to this concern, a study was conducted cooperatively with the National Park Service. The approach was to examine the water quality of the Indian River in the upper part of the watershed where no development has occurred and in the lower part of the basin where development has taken place.

Measurements of pH, water temperature, and dissolved oxygen concentrations of the Indian River were within acceptable ranges for fish survival. The Indian River is calcium bicarbonate type water with a low buffering capacity. Concentrations of dissolved ions and nutrients generally were low and exhibited little variation between the two study sites. Analysis of bed sediment trace element concentrations at both sampling sites indicates the threshold effect concentration was exceeded for arsenic, chromium, copper, nickel, and zinc; while the probable effect concentration was exceeded by arsenic, chromium and nickel. However, due to relatively large amounts of organic carbon present in the bed sediments, the potential toxicity from trace elements is low.

Discharge in the Indian River is typical of coastal southeast Alaska streams where low flows generally are in late winter and early spring and greater flows are during the wetter fall months. Alaska Department of Fish and Game has established instream flow reservations on the lower 2.5 miles of the Indian River. Discharge data indicate minimum flow requirements were not achieved during 236 days of the study period. Natural low flows are frequently below the flow reservations, but diversions resulted in flow reservations not being met a total of 140 days.

Thirty-five algae species were identified from the sample collected at Indian River near Sitka while 24 species were identified from the sample collected at Indian River at Sitka. Most species of algae identified in the Indian River samples were diatoms and the majority were pinnate diatoms; however, green algae and (or) blue-green algae accounted for much of the algal biomass at the two sites. The trophic condition of the Indian River is oligotrophic, and algal productivity likely is limited by low concentrations of dissolved nitrogen.

Few invertebrate taxa were collected relative to many high-quality streams in the contiguous United States, but the number of taxa in Indian River appears to be typical of Alaska streams. Ephemeroptera was the most abundant order sampled followed by Diptera.

Contents

Abstract

Introduction

Acknowledgment

Purpose and Scope

Description of Study Area

Methods of data collection and analysis

Water quality of the Indian River

Specific conductance

pH

Water temperature

Dissolved oxygen

Alkalinity

Major ions and dissolved solids

Nutrients and organic carbon

Suspended sediment

Trace elements in streambed sediments

Organic compounds

Flow characteristics of the Indian River

Indian River streamflow and diversions

Physical habitat and benthic communities of Indian River sites

Physical habitat

Algae

Macroinvertebrates

Summary and conclusions

References

Appendix

Suggested Citation:

Neal, E.G., Brabets, T.P., and Frenzel, S.A., 2004, Water quality and streamflow of the Indian River, Sitka, Alaska, 2001-2002: U.S. Geological Survey Scientific Investigation Report 2004-5023, 34 p.


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For more information about USGS activities in Alaska, visit the USGS Alaska District home page.




U.S. Department of the Interior, U.S. Geological Survey
Persistent URL: http://pubs.water.usgs.gov/sir20045023
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Last modified: Thursday, January 10 2013, 06:28:37 PM
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