Concepts for monitoring water quality in the Spokane River Basin, northern Idaho and eastern Washington

Numerous environmental studies have been
conducted in the Spokane River Basin over the
past several decades by government agencies,
academic institutions, and environmental engineering
firms. Most of these efforts have focused
on the environmental effects of more than a century
of silver, lead, and zinc mining and oreprocessing
activities in the South Fork Coeur
d'Alene River valley in northern Idaho. Several
studies also have assessed the water quality and
potential for eutrophication of Coeur d'Alene and
Long Lakes and the Coeur d'Alene, St. Joe, and
Spokane Rivers. Because past investigations often
were limited in scope and employed different
approaches and methods, an integrated understanding
of hydrologic, water-quality, and
aquatic biological conditions still is lacking for
the basin as a whole. Substantial resources are
being spent for water-quality and naturalresource
management, and for mitigating the
adverse environmental effects of past mining
activities in the basin. A water-quality monitoring
network, integrated with the decision-making
processes associated with these efforts, could be
of considerable value. The purpose of such a
monitoring network is to produce high-quality
information on which to base sound water-quality
and natural-resource management decisions
and to assess the effectiveness of those decisions.
A streamflow- and water-quality monitoring
infrastructure already exists in the Spokane River
Basin. This infrastructure consists of 20 lake-stage
and streamflow-gaging stations, representing
specific drainages or subdrainages and, in many
cases, specific stream reaches or subreaches.
These gaging stations are operated by the U.S.
Geological Survey (USGS), several of them in
cooperation with State and Federal agencies and
a private utility company. Extensive streamflow
data are available, some dating from the late
1800s. Water-quality data are also available from
recent USGS cooperative studies in the Coeur
d'Alene Lake watershed. A nutrient load/lake
response (eutrophication) model has been developed
for Coeur d'Alene Lake. Hydraulic models
for estimating streamflow through the low-gradient
reaches of the Coeur d'Alene and St. Joe
Rivers have been developed. Trace-element concentrations
and distributions in sediments in the
lower South Fork and main-stem Coeur d'Alene
River flood plain and the bed of Coeur d'Alene
Lake have been assessed. Trace-element transport
models have been developed for the lower
Coeur d'Alene River system; estimates of annual
load are available from the early 1990's to the
present (1998). The USGS is monitoring traceelement
concentrations and transport at seven
gaging stations in the lower Coeur d'Alene River
system and upper Spokane River, in cooperation
with the U.S. Environmental Protection Agency. Fish and macroinvertebrate community assessment
and tissue contaminant analyses at four
Coeur d'Alene and St. Joe River gaging stations
will begin in 1998, either as part of the Idaho Surface-
Water Quality Ambient Monitoring Network
operated by USGS in cooperation with the Idaho
Division of Environmental Quality, or for the
Northern Rockies Intermontane Basins (NROK)
study of the USGS National Water-Quality
Assessment (NAWQA) Program. Several gaging
stations in the Spokane River Basin are being considered
for routine sampling sites for the NROK
NAWQA study. Several other sites also will be
sampled for contaminants in bed sediment and
fish tissue for the NROK study.
Combined with appropriate sampling and
data interpretation strategies, the existing USGS
gaging-station network and data base could provide
integrated water-quality information needed
for sound environmental and resource-management
decisions throughout the Spokane River
Basin.