A digital water-quality model was constructed as part of a waterquality assessment of the Truckee River downstream from Reno. This report provides documentation on the computer code and the principal data sets used in model calibration, validation, and simulations. The TRWQ Model simulates mean daily concentrations of constituents at specified increments along the length of the modeled river reach. Simulated parameters include: Conservative variables (mass balance of all inputs and losses): Water discharge Dissolved solids Specific conductance (used as an easily-measured surrogate of dissolved solids) Nonconservative variables (mass balance of all inputs and losses coupled with first-order transformation and decay algorithms): Ultimate carbonaceous biochemical oxygen-demand (CBODu) Organic nitrogen Ammonia nitrogen Nitrite nitrogen Nitrate nitrogen Orthophosphorus (two values, see Appendix II) Total phosphorus Ratio of inorganic nitrogen to orthophosphorus Reaeration rate Dissolved oxygen EXAMPLE DATA SETS Listings of example data sets used as the basis for published TRWQ Model simulations are presented in Appendix II. These eight data sets include final calibrated and validated model parameters and input data reflecting conditions observed in the Truckee River and Truckee Canal during extensive field investigations in

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A program was designed for the systematic monitoring of groundwater quality in Nevada. Basic hydrologic and water-quality principles are discussed in the formulation of a rational approach to developing a statewide monitoring program. A review of groundwater monitoring efforts in Nevada through 1977 indicates that few requirements for an effective statewide program are being met. A suggested program has been developed that consists of five major elements: (1) A Background-Quality Network to assess the existing water quality in Nevada aquifers, (2) a Contamination Source Inventory of known or potential threats to groundwater quality, (3) Surveillance Networks to monitor groundwater quality in selected hydrographic areas, (4) Intensive Surveys of individual instances of known or potential groundwater contamination, and (5) GroundWater Data File to manage data generated by the other monitoring elements. Two indices have been developed to help assign rational priorities for monitoring ground water in the 255 hydrographic areas of Nevada: (1) A Hydrographic-Area Priority Index for surveillance monitoring, and (2) A Development-Potential Index for background monitoring of areas with little or no current development. Requirements for efficient management of data from groundwater monitoring are discussed and the three major systems containing Nevada groundwater data are reviewed. More than 11,000 chemical analyses of ground water have been acquired from existing systems and incorporated into a prototype data base.

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