Year of Award

2012

Document Type

Thesis - Campus Access Only

Degree Type

Master of Science (MS)

Degree Name

Environmental Studies

Department or School/College

Environmental Studies Program

Committee Chair

Vicki Watson

Commitee Members

D. Spencer, Will McDowell

Keywords

agriculture, Montana, riparian, SSTEMP, stream temperature

Abstract

Stream temperature impairment is a significant problem in the western United States and throughout Montana. Stream temperature is a measure of the amount of heat energy per unit volume of water. Change in either the amount of heat energy entering the stream or the amount of water flowing in the channel has the potential to alter stream temperature, and both natural and human influences can alter these characteristics. This thesis examines the relationship between the amount of riparian shade and mean, minimum, and maximum daily stream temperatures. In addition, this study examines the patterns of riparian vegetation conditions and how they relate to land-use practices within the drainage. These findings in turn indicate reaches in need of future riparian restoration projects, and land-use management plans. The two overarching goals are 1) to provide a background on the significance and implications of stream temperatures; and 2) to use Gold Creek, tributary of the upper Clark Fork River of western Montana, as a case study to examine further the relationship between existing riparian vegetation conditions and stream temperature loading. To document and examine the relationships between riparian vegetation, shade, and stream temperatures, six study reaches were delineated, each 100 meters long. Temperature loggers were placed at the top and bottom of each reach and were set to record stream temperature every 30 minutes from mid-July through October in 2011. Detailed riparian vegetation characteristics, including height, offset, and density were averaged and recorded for each reach. In addition, stream discharge was measured manually at the same locations where temperature loggers were placed. A heat flux model developed by USGS was used, called the Stream Segment Temperature Model, to help determine the strength of each field component and heat fluxes on stream temperature down the length of each reach. The model was calibrated with measured temperature data from the field. Instream temperature monitoring and heat flux modeling both indicate that stream temperatures in lower Gold Creek are likely at or greater than 66.5°F during part of the summer and fall. These temperatures are high enough to damage critical westslope cutthroat trout populations. In summer 2011, the lower two miles of Gold Creek showed a greater than 1 F increase over the naturally occurring (reference) temperature, indicating possible stream temperature impairment. The heat flux model used in this study indicates that increases in the amount of shade will likely reduce stream maximum temperatures. Dense riparian vegetation reduces exposure to solar radiation. This study reinforces the findings of several previous studies that increased shading reduces water temperature and hence aids stream restoration where temperatures are at stressful levels for aquatic life. The restoration of stream shade may be the most effective means of improving water quality and habitat in small agricultural streams such as Gold Creek.

Download

This record is only available
to users affiliated with
the University of Montana.

Request Access

Share

COinS
 

© Copyright 2012 Ashley Brandyn Burry-Trice