report

The table below lists all of the primary regulated drinking water contaminants that we detected during the calendar 2012 year of this report on finished water that has been treated. The presence of contaminants in the water does not necessarily indicate the water poses a health risk. Unless otherwise noted, the data presented in this table is from testing done in the calendar year of the report. The EPA or the State requires us to monitor for certain contaminants less than once per year because the concentrations of these contaminants do not change frequently.

Prepared By
Laurel Saito, Ph.D., P.E., Christa Fay, and Kristin Kvasnicka
Department of Natural Resources and Environmental Science, University of Nevada Reno
1000 Valley Road
Reno, NV 89512-0013

Prepared For
Karen Vargas, Environmental Specialist
Nevada Division of Environmental Protection
July 27, 2004

Introduction
Dr. Laurel Saito and her students at the University of Nevada Reno (UNR) have been collaborating with the United States Geological Survey (USGS), the Pyramid Lake Paiute Tribe (PLPT), the Desert Research Institute (DRI), and the Nevada Division of Environmental Protection (NDEP) to investigate the use of stable carbon and nitrogen isotopes to understand anthropogenic impacts on the aquatic ecosystem in the Truckee River. Previous work included stable isotope sampling and analysis of the Truckee River aquatic food web (i.e., fish and macroinvertebrates, and periphyton) in the summers of 2002 and 2003 during relatively low flows, and in the spring of 2003 during higher flows. The scope of the current study involved collecting another set of aquatic food web samples in March 2004 on the Truckee River for carbon and nitrogen stable isotope analysis. This report presents the methods and results of this sampling.

The Truckee River is a vital resource to Nevadans in the northwest region of the state. It provides public water supplies to the cities of Reno and Sparks, and while little irrigated agriculture occurs directly adjacent to the river, about one-third of its flow is diverted to the Lahontan Valley for irrigation purposes. The river terminates into Pyramid Lake, which has experienced severe declines in water level because of the heavy water diversions along its length. In addition, there are numerous resort and recreational activities throughout the basin, and the river and Pyramid Lake provide valuable water and habitat for endangered Lahontan cutthroat trout and cui ui species. In 1998, the USGS’s Nevada Basin and Range (NVBR) National Water-Quality Assessment (NAWQA) Program reported that while stream habitat at all sites (based on degradation indices related to riparian vegetation, stream modification, bank stability, and bank erosion) on the Truckee River system was better than the national median, fish communities in the lower reaches of the Truckee River were more degraded than the national median (Bevans et al. 1998). Furthermore, nutrients in the river and trace elements in its sediments increased 3 to 10 times downstream of the discharge from sewage treatment plants and the entrance of Steamboat Creek to the river. Thus, it appears that downstream influences on water quality and associated biological activity are detrimentally affecting the food web in the Truckee River.

The current work involves the use of stable carbon and nitrogen isotopes to gain insight into the aquatic food web. The use of stable isotopes in trophic studies employs the fundamental concept that ‘you are what you eat.’ Stable isotopes incorporate two kinds of information: origin and fractionation. The isotopic signature of an individual will reflect the signature of the sources of the isotopes (i.e., where the isotopes first entered the food web) and the change in the isotopic signature due to isotopic fractionation by consumption and metabolism in the food web (Peterson and Fry 1987). Because isotopes accumulate in body tissues over time, a one-time analysis of stable isotopes provides a time-integrated measure of the diet (Fry and Sherr 1984; Hesslein et al. 1993; Vander Zanden et al. 1998). Stable isotope analysis can even be used in food webs with omnivory because isotope values can be measured in all levels of the food web, including phytoplankton, zooplankton, and aquatic insects (Michener and Schell 1994; Vander Zanden and Rasmussen 1996; France 1997). Carbon and nitrogen ratios are the most commonly used stable isotope ratios in food web studies. Carbon ratios (?13C ) are used because the slight (0.2 – 1.1000) increase of ?13C in animals relative to their diet means that the ?13C signature of the primary producer (first organic food source) is likely to be preserved through several trophic levels (Peterson and Fry 1987; Michener and Schell 1994; Yoshioka et al. 1994; France and Peters 1997). Thus, carbon isotope analysis can be used to identify and distinguish the influence of different primary food sources if the isotopic signatures of those food sources are distinctive enough (Forsberg et al. 1993; Michener and Schell 1994). The nitrogen ratio (?15N ) is often used as an indicator of trophic position of a consumer (Fry 1988; Kling et al. 1992; Yoshioka et al. 1994) because the increase of ?15N with trophic level is much greater than with carbon (~3-4000 per trophic level) (Michener and Schell 1994).

Stable carbon and nitrogen isotopes have value in potentially detecting anthropogenic influences on aquatic food webs. Human- and animal-derived wastewater should have higher ?15N values because of the volatilization of 15N depleted ammonia which occurs during the hydroloysis of urea, and because humans tend to eat higher in the food chain, which elevates their waste nitrogen signatures (Heaton 1986; Silva et al. 2002; Wayland and Hobson 2001). On the other hand, synthetic fertilizers are typically derived by industrial fixation of atmospheric nitrogen (which has a reference signature of 0000), so waters draining fields using these fertilizers tend to have lower nitrogen signatures (Heaton 1986; Silva et al. 2002). Distinctive carbon signatures may be detected when aquatic-terrestrial interactions are altered (e.g. due to alteration of the stream channel and/or flooding regime) because terrestrial plants may have significantly different ?13C signatures than their aquatic counterparts. Such approaches have been used to detect the importance of autochthonous versus allochthonous material in streams (Rounick and Winterbourn 1986; Finlay et al. 1999). In addition, shifts in food web dynamics such as shifts in diets or elimination of species may be detectable with stable isotopes; if the food chain shortens, we should see shifts in nitrogen signatures in the top predators, and if a food source is eliminated at the base of the food web, we may see shifts in the carbon signature.

Prepared By

Prepared For

Summary

The objective of our analysis was to develop a biological index for benthic macroinvertebrates for the Nevada portion of the mainstem of the Truckee River using preexisting data. We analyzed data collected by four separate entities, Nevada Division of Environmental Protection (NDEP), Pyramid Lake Paiute Tribe (PLPT), Truckee Meadows Water Reclamation Facility (TMWRF), and Desert Research Institute (DRI). To develop a common dataset from collections of multiple entities, an evaluation of the field and/or lab methodological differences was performed to minimize non-random error. A common index period was designated as low flow (July to October), all replicates were combined, and the number of individuals per sample was set to 500 organisms (samples with more organisms were randomly sampled with a computer to 500).

A multimetric index was developed from the data set and comprised six metrics or attributes of the benthic macroinvertebrate assemblage; total taxa, percent Ephemeroptera, percent Chironomidae, percent dominant taxon, percent filterers, and percent clingers. In an assessment, each metric value is converted to a standard score ranging between 0 and 100 (100 being closest to reference or optimal value). The scores for all six metrics are averaged to obtain an aggregated index score and compared to thresholds or break points based on percentages of the overall score and expected conditions for a good quality benthic macroinvertebrate community. Application of the benthic index to the mainstem of the Truckee River indicated the biological condition was of higher quality in the upper reaches and declined in quality as the river approaches Pyramid Lake. A more definitive assessment is pending the results of the analyses on companion assemblages of the aquatic community, namely the fish and algal assemblages.

Prepared By
Clinton J. Davis and Christian H. Fritsen
Desert Research Institute
2215 Raggio Parkway
Reno NV, 89512

Prepared For
Nevada Division of Environmental Protection
February 6, 2006

Summary
The objectives of the current activities were to determine if sufficient data was available to derive preliminary periphyton-based metrics that could be used in a periphyton-based indices of ecological condition for the Lower Truckee River, which could in turn be used to derive more comprehensive indices of biological integrity (IBI) based on fish, macroinvertebrates and periphyton populations. Derivation of metrics and indices was made possible through the use of relatively recent (2000 to 2004) seasonal periphyton data that was collected from 11 to 15 locations from California-Nevada border to Pyramid Lake. Although, the levels of taxonomic information from the different data sets were not always comparable, several candidate metrics and indices encompassing information from both the species level and the genera level were identified, calculated and evaluated.

Notable among the metrics most amenable for a Truckee River Periphyton Index were the Siltation Index, Shannon Diversity Index, Eutraphentic Index, Diatom Generic Richness, % Achnanthes minutissima, Chlorophyll a and Ash Free Dry Weight. These metrics covered several aspects of the periphyton community characteristics (richness, composition, tolerance, and habit) that are desired attributes to be accounted for in multimetric indices.

Application of a periphyton-based multimetric index to the mainstem of the Truckee River indicates a general upstream to downstream trend for decreasing ecological condition. However, these results are based on a limited amount of periphyton data and also need to be evaluated in combination with Index’s for fishes and macroinvertebrates in order to gain a more complete picture of the “condition” of the lower Truckee River.

Prepared For

U.S. Fish & Wildlife Service
Nevada State Office, Reno, Nevada 89502 (March 6, 2004)

Summary

The factors controlling nitrogen availability, and hence algal productivity, in Pyramid Lake differ from those in the Truckee River, and therefore, an assessment of the impacts of water management strategies must reflect those differences. As a lake, algal production in Pyramid is affected by total available nitrogen from external sources, internal sources, and the nitrogen concentration of lake waters. This dependence of production on a variety of nitrogen sources means that nitrogen availability for a given year depends on the supply of nitrogen to the lake over several years rather than simply during the current year. The Davis Limnology Group developed in 1994 a computer simulation modeling tool that predicts the eutrophication response of Pyramid Lake as a whole to nitrogen loadings. In the past, the U.C. Davis Tool was used to evaluate how different Truckee River Operating Agreement (TROA) alternatives may affect the coldwater fishery of Pyramid Lake for the report to the negotiators (1995) and the DEIS/EIR (1996) compared with current conditions and the No Action Alternative. This study evaluates the TROA alternative developed for the TROA EIS/EIR and compares predictions with current conditions, the No Action Alternative, and a Local Water Supply Alternative (LWS).

Simulated water quality for the lake under current conditions are similar to conditions reported during the 1970's and 1980's. Mean lake concentrations for dissolved inorganic (DIN) and dissolved organic (DON) nitrogen during the final 87 years of the simulation were 0.091 and 0.69 mg/l, respectively, while average algal production was 173 g C/m2?yr. Spikes in the simulated values for the DIN concentration in the lake and annual algal production were associated with years of high river inflow.

The impact of the Alternatives on food availability and habitat for the coldwater fish population of Pyramid Lake was evaluated by comparing values for No Action with values determined for current conditions and by comparing the TROA and LWS Alternatives with the No Action Alternative. Conditions for the No Action Alternative were similar to current conditions, with lower river inflow and corresponding coldwater fishery habitat. Under the TROA Alternative, Truckee River inflow to Pyramid Lake increased by 11,500 acre?ft/yr causing mean lake level for 1913-1999 to be 3.2 ft higher than under the No Action Alternative. This increase in river inflow for the TROA Alternative corresponded with higher predicted DIN loading (3.9 Mg N/yr) and DON loading (13.1 Mg N/yr). Differences in lake characteristics for TROA and the No Action Alternative were relatively small but generally benefited the coldwater fishery of Pyramid Lake. The LWS Alternative provided results similar to the No Action Alternative.

The Truckee River Water Quality Agreement of 1997 settled longstanding litigation between the Pyramid Lake Paiute Tribe (PLPT) and the U.S. Environmental Protection Agency (EPA), State of Nevada and the Cities of Reno and Sparks (“Cities”), respectively. A key element of this agreement was a commitment by the Cities and the Department of the Interior to spend up to $24 million to purchase Truckee River water rights from downstream of Sparks. Water would subsequently be sorted in upper basin reservoirs for release under low-flow conditions to help the Cities meet water quality objectives, particularly those related to nutrients and dissolved oxygen. It was further anticipated that a reduction in irrigated agriculture within the Fernley area would result in an associated decrease in high total dissolved solids (TDS) groundwater discharge to the river, helping to mitigate salinity loading to Pyramid Lake.

A hydrogeologic investigation was undertaken to characterize the groundwater system in the Fernley Basin and to determine the TDS loading to the Truckee River between the towns of Wadsworth and Nixon. A groundwater flow and transport model was constructed to integrate all of the available data and to predict the potential loadings under various management alternatives.

Written By

Prepared For
Pyramid Lake Paiute Tribe
Nevada Division of Environmental Protection
April 2005
Summary
We developed a fish assemblage IBI for western Nevada rivers and applied it to the Truckee River. Available state and federal fish assemblage data from the Carson, Walker, and upper Truckee rivers were analyzed to select and score metrics. Selected metrics included number of native species, % sculpin individuals, % mountain whitefish individuals, evidence of sculpin and whitefish reproduction, % cutthroat trout individuals, % sensitive individuals, % mountain sucker individuals, % omnivorous individuals, % highly tolerant individuals, % alien individuals, and % external anomalies. Metrics were scored continuously from 0-1 and the IBI was scored from 0-10 by summing the metrics. Those metrics and scoring criteria were then applied to existing fish assemblage data for the lower Truckee River. The IBI declined from the Nevada border to Wadsworth, with sharp declines at river miles 57 (Oxbow), 69 (Mustang), and 87 (Painted Rock). Revisits to the same sites indicated that IBI scores may vary by 1.0 as a result of temporal and sampling variation. We consider median IBI scores >7.5 as acceptable, 5.0-7.4 as marginally damaged, and <5.0 as damaged. However, these are only guidelines and 2.0 changes in IBI scores over space or time are probably biologically significant.