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DRI’s
Long History with a Short River
DRI’s research
on the problem of salinity and total dissolved solids is only one
part of a long history of research on the Truckee River. Other DRI
research interests have ranged from issues with the quality and
quantity of the river’s water itself, to questions about the
ecological health of its source in the Lake Tahoe Basin, to debates
over the river’s role in the future existence of the struggling
Lahontan cutthroat trout and endangered cui-ui fish species in its
terminus at Pyramid Lake.
River quality clues in the mud.
DRI Laboratory Technician Jeramie Memmott samples mud from
the bottom of the Truckee River to analyze for periphyton
growth. The data will give an indication of the amount of
algal growth that might occur in the area. (Photo by John
Doherty) |
From the mid 1960s to
the early 1970s, DRI conducted a major feasibility study of using
Sierra Nevada cloud seeding operations to counteract the dropping
level of Pyramid Lake due to agricultural and municipal diversions
from the river. The study showed that cloud seeding could not maintain
Pyramid Lake, but it could produce a significant amount of inexpensive
water.
Since 1972, DRI scientists
and, more often, graduate research assistants, have conducted monthly
water sampling runs along the length of the river, tracking more
than twenty different water quality parameters. The monitoring program
is conducted for the State of Nevada Division of Environmental Protection,
which forwards the data to the U.S. Environmental Protection Agency’s
STORET (storage and retrieval) national database.
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Looking under rocks for Truckee River
biomass. Dale Casale, Washoe
County Department of Water Resources, left, and undergraduate
research assistant and UNR student Clint Davis remove algal
material from cobble, or river rock. The sample will be analyzed
for chlorophyll content and several other factors that will
indicate growth rates and primary nutrients for biological
material in the river. (Photo by John Doherty) |
The problems of sediment
loading and how to predict it are the subject of two recent studies
looking upstream from Reno. One project, funded by the Lahontan
Region of the California Water Quality Control Board, is working
to develop a background estimate using turbidity measurements of
the sediment load for the Truckee River in California, including
the likely variability of the amount of sediments carried by the
river under different conditions such as spring snowmelt, summer
cloud bursts, normal winter storms, etc.. That estimate, referred
to as a “sediment surrogate,” would provide a guide
for water quality monitoring to identify sediment loading conditions
that might be damaging to the river ecology, i.e., the loss of habitat
for insects critical to the aquatic food chain.
That project also builds
on the results of another recent study designed to develop a model
for simulating erosion and sediment loading in each of the main
watershed areas contributing to the overall condition of the upper
Truckee River. The model, based on a geographic information system
(GIS), allows water quality managers to estimate the likely changes
in sediment loading under various land use decisions. Based on the
watershed analysis, the project was also able to recommended targets
for reducing sediment loads in different reaches of the river.
Down river from Reno,
DRI scientists have been looking at how the flow of groundwater
into the river affects the growth of algae and how various management
strategies might mitigate algal growth.
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Green zone.
A massive algal bloom growing from cobbles in the shallows
of the Truckee River just upstream from the Tracy/Clark bridge
off I-80 east of Reno. (Photo by Mark B. Green, DRI graduate
research assistant) |
Another DRI study has
examined the influence of riverside vegetation on the local climate
and the temperature of the water, with particular attention to shaded
areas and pools where fish are able to survive hot summers and low
flows. Cooler temperatures and reduced sunlight appear to help prevent
the loss of dissolved oxygen essential for aquatic species. That
temperature and climate data is then incorporated into models that
can indicate sites for riverbank restoration or other management
options to improve aquatic habitats.
A related effort is collecting
data on factors related to algal biomass—plant pigments (chlorophyll),
carbon, nitrogen and phosphorous—in the lower Truckee River
that can be used to develop independent analyses of ecosystem health
and nutrient budgets. The biomass sampling information will also
be available for incorporation into water quality models, improving
the models’ usefulness as management tools.
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