REMOTE SENSING OF WATER QUALITY IN FLAMING GORGE RESERVOIR 
WYOMING-UTAH, USA 
by 
JAMES P. VERDIN 
Bureau of Reclamation 
PO Box 25007, Code D-1524 
Denver, Colorado, U.S.A. 80225 
ABSTRACT 
Bureau of Reclamation water quality specialists surveyed Flaming Gorge Reser- 
voir, Wyoming-Utah, concurrent with two remote sensing missions on September 9, 
1981. Landsat 2 and the EPA (Environmental Protection Agency) airborne scanner 
each acquired multispectral imagery of the reservoir. Analyses of the data were 
performed in the Bureau's digital image processing laboratory. Useful relation- 
ships were found between remotely sensed data and contact measurements of water 
clarity, chlorophyll a concentration and total phosphorus concentration. 
These relationships were exploited to make estimates of the water quality 
variables in unsampled reaches of the reservoir, as well as to produce thematic 
water quality maps. 
INTRODUCTION 
The Bureau of Reclamation, an agency of the U.S. Department of Interior, is 
responsible for over 300 reservoirs in the 17 Western States. These reservoirs 
are managed to supply water for irrigation, municipal and industrial use, 
production of hydroelectric power, and provision of recreation and fishery. 
Maintenance of water quality is a high priority of the agency. 
Flaming Gorge Reservoir, at an elevation of 2000 meters on the Green River in 
Utah and Wyoming, is a large impoundment extending roughly 140 kilometers 
upstream from the damsite. The region has an arid climate, receiving 300 mm of 
precipitation in a typical year. The reservoir is filled by spring snowmelt 
from local ranges of the Rocky Mountains. The dam was completed in 1964, the 
waters stored to meet downstream commitments and to produce hydroelectric power. 
The reservoir and adjacent lands comprise Flaming Gorge National Recreation 
Area. 
DATA ACQUISITION 
A comprehensive limnological survey of Flaming Gorge Reservoir was conducted by 
Bureau water quality specialists on September 9 and 10, 1981. On the first day, 
sampling was conducted at 18 sites in the upper three-fourths of the reservoir. 
Seven more sites of the lower reservoir were visited the next day (Wegner and 
Miller, 1981). The purpose of the survey was to obtain water quality data at a 
time of year when the symptoms of eutrophication are at their peak. In general, 
the upper reaches of the reservoir can be characterized as eutrophic, the lower 
reaches as oligotrophic, with a mesotrophic zone of transition in between. The 
sampling was conducted to be concurrent with the September 9 pass of Landsat 2 
at that location. 
Landsat 2 acquired its image of the reservoir at 11:20 a.m. MDT on September 9, 
1981. Computer compatible tapes of the image were purchased from the U.S. 
Geological Survey EROS Data Center at Sioux Falls, South Dakota. The image was 
supplied in standard EDIPS format, with the data resampled by cubic convolution 
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