| ACLs | Alternate Concentration Limits |
| ACEC | Area of Critical Environmental Concern |
| AF | Acre-Feet (or Acre-Foot) |
| AFY | Acre-Feet per Year |
| AGP | Algal Growth Potential |
| AMC | Antecedent Moisture Condition |
| AMD | Acid Mine Drainage |
| ANC | Acid Neutralizing Capacity |
| API | Antecedent Precipitation Index |
| APWA | American Public Works Association |
| ARARs | Applicable, Relevant, or Appropriate Requirements |
| ARMA | AutoRegressive Moving Average |
| ARS | Agricultural Restructuring Scenario |
| ASC | Atmospheric Sciences Center (DRI) |
| ASCE | American Society of Civil Engineers |
| ASOS | Automated Surface Observing Systems (NWS/NOAA) |
| ATP | Adenosine Triphosphate |
| ATU | Aerobic Treatment Unit |
| AUM | Animal Unit Month |
| AW | Applied Water |
| AWC | Available Water Content |
| AWT | Advanced Wastewater Treatment |
| AWWA | American Water Works Association |
| BAC | Biological Activated Carbon [Process] |
| BADT | Best Available Demonstrated Technology |
| BAT | Best Available Technology [Economically Achievable] |
| B.P. | Before Present |
| BCF | Bioconcentration Factor |
| BCP | Bioconcentration Potential |
| BCT | Best [Conventional] Control Technology |
| BFE | Base Flood Elevation (FEMA) |
| BGS | Balanced Groundwater Scenario |
| BIA | Bureau of Indian Affairs (USDI) |
| BLM | Bureau of Land Management (USDI) |
| BMP | Best Management Practice [Urban Water Use] |
| BOD | Biochemical Oxygen Demand/Biological Oxygen Demand |
| BOD5 | Biological Oxygen Demand-5 Days |
| BOR | (U.S.) Bureau of Reclamation (USDI) |
| BP | Barometric Pressure |
| B.P. | Before Present (Time) |
| BPI | Bureau of Plant Industry [Evaporation Pan] (USDA) |
| BPT | Best Practicable Control Technology |
| BSC | Biological Sciences Center (DRI) |
| BTU | British Thermal Unit |
| BWPC | Bureau of Water Pollution Control (NDEP/DCNR) |
| BWQP | Bureau of Water Quality Planning (NDEP/DCNR) |
| BWR | Boiling Water Reactor |
| C | Celsius (Centigrade Temperature Scale) |
| CAA | Clean Air Act (EPA) |
| CAPA | Critical Aquifer Protection Area (SDWA) |
| CBRA | Coastal Barrier Resources Act of 1982 (FEMA) |
| CBRS | Coastal Barrier Resources System (FEMA) |
| CCE | Carbon-Chloroform Extract |
| CDI | Capacitive Deionization |
| CEC | Cation Exchange Capacity |
| CEQA | California Environmental Quality Act |
| CERCLA | Comprehensive Environmental Response, Compensation, and Liability Act (EPA) |
| CERES | California Environmental Resources Evaluation System |
| CFCs | Chlorofluorocarbons |
| CF | Cubic Feet (or Foot) |
| CFR | Code of Federal Regulations |
| CFS (cfs) | Cubic Feet per Second |
| CFSM | Cubic Feet per Second per Square Mile |
| CIR | Consumptive Irrigation Requirement/Crop Irrigation Requirement |
| CLR | Classical Linear Regression [Model] |
| CLOMR | Conditional Letter of Map Revision (FEMA) |
| CMI | Crop Moisture Index |
| COI | Cone of Influence |
| COD | Chemical Oxygen Demand |
| COD | Cone of Depression |
| CORPs | U.S. Army Corps of Engineers (also USACE) |
| CP | Cultural Practices |
| CPI | Consumer Price Index |
| CSO | Combined Sewer Overflow |
| CSS | Combined Sewer System |
| CVP | Central Valley Project (State of California) |
| CWA | Clean Water Act (EPA) |
| CZMA | Coastal Zone Management Act |
| DBH | Diameter at Breast Height |
| DBPs | Disinfection By-Products |
| DCNR | Department of Conservation and Natural Resources (State of Nevada) |
| D/DBP | Disinfectant and Disinfection By-Product Rule (EPA) |
| DEIS | Draft Environmental Impact Statement (NEPA/EPA) |
| DEP | Division of Environmental Protection (DCNR) |
| DNAPLs | Denser (than water) Non-Aqueous-Phase Liquids |
| DO | Dissolved Oxygen |
| DOC | Dissolved Organic Carbon |
| DOF | Division of Forestry (DCNR) |
| DOW | Division of Wildlife (DCNR) |
| DDT | Dichlorodiphenyltrichloroethane |
| DRI | Desert Research Institute (University of Nevada System, State of Nevada) |
| DU | Distribution Uniformity |
| DW | Distilled Water |
| DWR | Division of Water Resources (DCNR) |
| DWR | Department of Water Resources (The Resources Agency, State of California) |
| DWP | Division of Water Planning (DCNR, also NDWP) |
| EA | Environmental Assessment (NEPA) |
| EA | Endangerment Assessment (EPA) |
| EC | Electrical Conductivity/Electroconductivity |
| EDF | Environmental Defense Fund |
| EDI | Equal Discharge Increment |
| EDR | Electrodialysis Reversal |
| EEEC | Energy and Environmental Engineering Center (DRI) |
| EIS | Environmental Impact Statement (NEPA/EPA) |
| ENSO | El Ni?o/Southern Oscillation |
| EPA | [U.S.] Environmental Protection Agency |
| EPAct | (National) Energy Policy Act |
| ESA | Endangered Species Act (USFWS) |
| ESWTR | Enhanced Surface Water Treatment Rule (EPA) |
| ET | Evapotranspiration |
| ETAW | Evapotranspiration of Applied Water |
| ETR | Equal Transit Rate |
| EWMP | Efficient Water Management Practice [Agricultural Water Use] |
| ç | Viscosity [eta] |
| F | Fahrenheit (Temperature Scale) |
| FBFM | Flood Boundary Floodway Map (FEMA) |
| FEMA | Federal Emergency Management Agency |
| FERC | Federal Energy Regulatory Commission |
| FHBM | Flood Hazard Boundary Map (FEMA) |
| FIA | Federal Insurance Administration (FEMA) |
| FIFRA | Federal Insecticide, Fungicide, and Rodenticide Act (EPA) |
| FIRM | Flood Insurance Rate Map (FEMA) |
| FIS | Flood Insurance Study (FEMA) |
| FLMPA | Federal Land Management and Policy Act |
| FOE | Friends of the Earth |
| FONSI | Finding of No Significant Impact (NEPA) |
| FPE | Flood Protection Elevation (FEMA) |
| FS | Feasibility Study (EPA) |
| FSA | Food Security Act (USDA) |
| FTE | Full Time Equivalent (Employment) |
| FWS | Free Water Surface |
| GAC | Granular Activated Carbon |
| GACT | Granular Activated Carbon Treatment |
| GC | Gas Chromatography |
| GC/FID | Gas Chromatography/Flame Ionization Detector |
| GC/MS | Gas Chromatography/Mass Spectrometer |
| GCMs | General Circulation Models |
| GD | Geologic Division (USGS) |
| GDP | Gross Domestic Product |
| GED | Gallon per Employee per Day |
| GFD | Gallons per Square Foot [of membrane] per Day |
| G.H. | Gage Height (USGS) |
| GID | General Improvement District |
| GIS | Geographic Information System |
| GMW | Gram Molecular Weight |
| GPC | Gallons per Capita (Person) |
| GPCD | Gallons per Capita per Day |
| GPD | Gallons per Day |
| GPED | Gallons per Employee per Day |
| GPS | Global Positioning System |
| GSA | [Federal] General Services Administration |
| GWH | Gigawatt-Hour |
| ?d | Dry Adiabatic Lapse Rate [gamma] |
| ?s | Wet (Saturated) Adiabatic Lapse Rate [gamma] |
| HGL | Hydraulic Grade Line |
| HCP | Habitat Conservation Plan (EPA) |
| HRS | Hazardous Ranking System (EPA) |
| HSA | Hydrologic Study Area (DWR, State of California) |
| HT | High Tide |
| HW | High Water |
| HWM | High Water Mark |
| i | Hydraulic Gradient |
| ICR | Information Collection Rule (EPA) |
| I.E. | Irrigation Efficiency |
| IOWE | International Office for Water Education (Utah State University) |
| IRP | Integrated Resource Planning |
| JTU | Jackson Turbidity Unit |
| K | Hydraulic Conductivity |
| K | Kelvin (temperature scale) |
| Kd | Soil Sorption Coefficient |
| k | Kinetic Energy |
| KGAL | Kilogallons (thousand gallons) |
| KGRA | Known Geothermal Resource Area |
| KW | Kilowatt |
| KWH | Kilowatt-Hour |
| LA | Load Allocation |
| LC50 | Lethal Concentration-50 (percent) |
| LCA | Life Cycle Assessment |
| LCT | Lahontan Cutthroat Trout (USFWS) |
| LD50 | Lethal Dose-50 (percent) |
| LI | Langelier Index |
| LN | Natural Logarithm |
| LNAPLs | Lighter (than water) Non-Aqueous-Phase Liquids |
| LOMA | Letter of Map Amendment (FEMA) |
| LOMR | Letter of Map Revision (FEMA) |
| LR | Leaching Requirement |
| lsd | Land Surface Datum |
| LTAR | Long Term Acceptance Rate [of Soils] |
| LVEA | Lahontan Valley Environmental Alliance |
| LW | Low Water |
| LWM | Low Water Mark |
| LWR | Light Water Reactor |
| ? | Scavenging Coefficient [lambda] |
| MAF | Million Acre-Feet |
| M&I | Municipal and Industrial |
| MATC | Maximum Acceptable Toxicant Concentration |
| MBAS | Methylene Blue Active Substance |
| MCL | Maximum Contaminant Level (EPA) |
| MCLG | Maximum Contaminant Level Goal (EPA) |
| MEQ/L | Milliequivalents per Liter |
| MGD | Million Gallons per Day |
| MG/L (mg/l) | Milligrams per Liter |
| MHW | Mean High Water |
| MIS | Management Indicator Species |
| MLSS | Mixed Liquor Suspended Solids |
| MLVSS | Mixed Liquor Volatile Suspended Solids |
| MLW | Mean Low Water |
| MP | Measuring Point |
| MPA | Microscopic Particulate Analysis |
| MPN | Most Probable Number |
| MPRSA | Marine Protection, Research, and Sanctuaries Act (EPA) |
| MS | Mass Spectrometry |
| MSL | [Elevation above] Mean Sea Level |
| MTBE | Methyl Tertiary Butyl Ether |
| MW | Megawatt (one million watts) |
| MYA | Million Years Ago |
| ? | Micron (one-millionth of a meter) [mu] |
| NAPLs | Non-Aqueous-Phase Liquids |
| NASQAN | National Stream Quality Accounting Network (USGS) |
| NBMG | Nevada Bureau of Mines and Geology |
| NCP | National Contingency Plan (EPA) |
| NCWS | Non-Community Water System |
| NDEP | Nevada Division of Environmental Protection (DCNR) |
| NDEPS | National Pollutant Discharge Elimination System (EPA) |
| NDOW | Nevada Division of Wildlife (DCNR) |
| NDSP | Nevada Division of State Parks (DCNR) |
| NDT | Nondestructive Testing |
| NDWP | Nevada Division of Water Planning (DCNR) |
| NDWR | Nevada Division of Water Resources (State Engineer's Office, DCNR) |
| N.E.C. | Not Elsewhere Classified (SIC Codes) |
| NEPA | National Environmental Policy Act (EPA) |
| NESDIS | National Environmental Satellite, Data and Information Service (NOAA) |
| NEXRAD | Doppler Radar Data System (NWS/NOAA) |
| NFIP | National Flood Insurance Program (FEMA) |
| NFS | National Forest Service (USDA) |
| NGVD | National Geodetic Vertical Datum |
| NHP | [Nevada] Natural Heritage Program (DCNR) |
| NIDS | NEXRAD Information Dissemination Service (NWS/NOAA) |
| NIFC | National Interagency Fire Center (BLM) |
| NIPDWR | National Interim Primary Drinking Water Regulations |
| NM | Nautical Mile |
| NMD | National Mapping Division (USGS) |
| NMFS | National Marine Fisheries Service (NOAA) |
| NOAA | National Oceanic and Atmospheric Administration (U.S. Department of Commerce) |
| NOHSCP | National Oil and Hazardous Substances Contingency Plan (EPA) |
| NOS | National Ocean Service (NOAA) |
| NOW | Nonhazardous Oil Field Waste (EPA) |
| NOx | Oxides of Nitrogen |
| NPDES | National Pollutant Discharge Elimination System (NDEP/EPA) |
| NPDWR | National Primary Drinking Water Regulations (SDWA/EPA) |
| NPL | National Priorities List ["Superfund" List] (EPA) |
| NPS | Non-Point Source [Pollution] |
| NPS | National Park Service (USDI) |
| NRC | National Research Council |
| NRC | National Response Center (U.S. Coast Guard) |
| NRCS | Natural Resources Conservation Service (USDA) |
| NRDC | Natural Resources Defense Council (private environmental organization) |
| NRP | Natural Resources Plan (DCNR) |
| NRP | National Research Program [Centers] (WRD/USGS) |
| NRT | National Response Team (EPA) |
| NSDWR | National Secondary Drinking Water Regulations |
| NSF | National Strike Force (U.S. Coast Guard) |
| NSPS | New Source Performance Standards (EPA) |
| NTU | Nephelometric Turbidity Unit |
| NVS | Non-Volatile Solids |
| NVSS | Non-Volatile Suspended Solids |
| NWIC | National Water Information Clearinghouse (USGS) |
| NWPA | Newlands Water Protective Association |
| NWR | National Wildlife Refuge [System] (USFWS) |
| NWS | National Weather Service (NOAA) |
| O&M | Operations and Maintenance |
| OC | Organic Carbon |
| OCAP | Operating Criteria and Procedures (TCID/USBR) |
| OFA | Other Federal Agencies [Program] (WRD/USGS) |
| OLS | Ordinary Least Squares (statistics) |
| OM&R | Operations, Maintenance, and Replacement |
| OSM | Office of Surface Mining Reclamation and Enforcement (Bureau of Mines/USDI) |
| OTEC | Ocean Thermal Energy Conversion |
| PAHs | Polycyclic Aromatic Hydrocarbons, or Polararomatic Hydrocarbons |
| PAMs | Polyacrylamides |
| PCBs | Polychlorinated Biphenyls |
| PCE | Perchloroethylene |
| PCNs | Polychlorinated Naphthalenes |
| PCWCD | Pershing County Water Conservation District [Nevada] |
| PDC | Project Dependable Capacity |
| PDSI | Palmer Drought Severity Index |
| PE | Population Equivalent |
| pH | Hydrogen Ion Concentration [Potential of Hydrogen] |
| PHS | Public Health Service |
| PIA | Practicably Irrigable Acreage |
| P.L. | Public Law |
| PLSS | Public Land Survey System |
| PMF | Probable Maximum Flood (FEMA) |
| PNAs | Polynuclear Aromatic Hydrocarbons |
| POC | Point of Compliance |
| POE | Point-of-Entry [Treatment Device] |
| POM | Particulate Organic Matter |
| POSW | Privately-Owned Stored Water |
| POTW | Publicly-Owned Treatment Works |
| POU | Point-of-Use [Treatment Device] |
| PPB | Parts per Billion |
| PPM | Parts per Million |
| PPT | Parts per Thousand |
| PRP | Potentially Responsible Party (EPA) |
| PS | Point Source [Pollution] |
| PSA | Primary Settlement Agreement |
| PSP | Paralytic Shellfish Poisoning |
| PWR | Pressurized Water Reactor |
| PWS | Public Water System/Public Water Supply |
| PWSS | Public Water Supply System |
| PWSSP | Public Water System Supervision Program |
| ? | Infiltration Index [phi] |
| Q | Volumetric Flow Rate (Venturi Effect) |
| QBO | Quasi-Biennial Oscillation (ENSO) |
| QPF | Quantitative Precipitation Forecast |
| QSC | Quaternary Sciences Center (DRI) |
| R | R?aumur (or Reaumur) Thermometer Scale |
| R | Correlation Coefficient |
| R2 | Coefficient of Determination |
| RBC | Rotating Biological Contractor |
| RCRA | Resource Conservation and Recovery Act (EPA) |
| RDI | Reclamation Drought Index |
| Re/? | Reynolds Number |
| RFD | Regulatory Flood Datum (FEMA) |
| RI | Remedial Investigation (EPA) |
| RI/FS | Remedial Investigation/Feasibility Study (EPA) |
| RMCL | Recommended Maximum Containment Level |
| RMHQs | Requirements to Maintain Existing Higher Quality (NDEP/DCNR) |
| RMP | Resource Management Plan (BLM) |
| ROE | Residue on Evaporation |
| RRT | Regional Response Team (EPA/U.S. Coast Guard) |
| RSC | Residual Sodium Carbonate |
| RVD | Recreation Visitor Day |
| 7Q10 | Seven-Day 10-Year Low Flow |
| S.A. | Seasonally Adjusted |
| SAB | Science Advisory Board (EPA) |
| SAE | Seasonal Application Efficiency |
| SAR | Sodium Adsorption Ratio |
| SAS | Soil Absorption System |
| SAS | Solar Aquatic Systems |
| SB | Sedimentation Basin |
| SBR | Sequencing Batch Reactors |
| SCS | Soil Conservation Service (now NRCS) |
| SDI | Stand Density Index |
| SDWA | Safe Drinking Water Act (EPA) |
| SF | Subsurface Flow |
| SFHA | Special Flood Hazard Area (FEMA) |
| SFIP | Standard Flood Insurance Policy (FEMA) |
| SG | Specific Gravity |
| SHR | Significant Hydrologic Resources |
| SI | [Le] Syst?me International [d'Unit?s] (Metric System) |
| SIC | Standard Industrial Classification [Code] |
| SLPA | Sea Level Pressure Anomaly (ENSO) |
| SMCL | Secondary Maximum Contaminant Level (EPA) |
| SMZ | Streamside Management Zone (USFWS) |
| SNOTEL | Snowpact Telemetry (NRCS) |
| SOC | Suspended Organic Carbon |
| SOC | Synthetic Organic Chemical |
| SOD | Sediment Oxygen Demand |
| SP GR | Specific Gravity |
| SP HT | Specific Heat |
| SPCCP | Spill Prevention Control and Countermeasures Plan (CWA) |
| SPF | Standard Project Flood |
| SPI | Standardized Precipitation Index |
| SRP | Soluble Reactive Phosphate |
| SS | Suspended Solids |
| SSA | Sole Source Aquifer |
| SSTA | Sea Surface Temperature Anomaly (ENSO) |
| STE | Septic Tank Effluent |
| ST-SAS | Septic Tank Soil Absorption System |
| SV | Sludge Volume |
| SVI | Sludge Volume Index |
| SWAP | Source Water Protection Program (EPA) |
| SWCS | Soil and Water Conservation Society |
| SWE | Snow Water Equivalent |
| SWP | State Water Project (State of California) |
| SWPP | Source Water Protection Program (EPA) |
| SWRCB | State Water Resources Control Board (DWR/State of California) |
| SWSI | Surface Water Supply Index |
| SWTR | Surface Water Treatment Rule (SDWA) |
| ? | Standard Deviation [sigma] |
| ?2 | Variance [sigma squared] |
| TC | Total Carbon |
| TCID | Truckee-Carson Irrigation District [Nevada] |
| TCLP | Toxicity Characteristic Leaching Procedure (EPA) |
| TDEM | Time-Domain Electromagnetics |
| TDS | Total Dissolved Solids |
| TES | Threatened, Endangered or Sensitive Species (USFWS) |
| TES | Terrestrial Ecosystem Survey |
| THMs | Trihalomethanes |
| ThOD | Theoretical Oxygen Demand |
| TIC | Total Inorganic Carbon |
| TIN | Total Inorganic Nitrogen |
| TIP | Total Inorganic Phosphate |
| TKN | Total Kjeldahl Nitrogen |
| TMDL | Total Maximum Daily Load (EPA) |
| TNC | The Nature Conservancy |
| TOC | Total Organic Carbon |
| TON | Threshold Odor Number |
| TOT | Time of Travel |
| TROA | Truckee River Operating Agreement [California and Nevada] |
| TRPA | [Lake] Tahoe Regional Planning Agency [California and Nevada] |
| TS | Total Solids |
| TSCA | Toxic Substances Control Act (EPA) |
| TSI | [Carlson's] Trophic State Index |
| TSI | [Mean] Trophic State Index |
| TSS | Total Suspended Solids |
| TTHMs | Total Trihalomethanes |
| TVA | Tennessee Valley Authority |
| ô | Coefficient of Transmissivity [tau] |
| UDI | [Ground Water] Under the Direct Influence [of Surface Water] |
| UIC | Underground Injection Control |
| UMTRCA | Uranium Mill Tailings Radiation Control Act (EPA) |
| USACE | U.S. Army Corps of Engineers (also Corps) |
| USBR | U.S. Bureau of Reclamation (USDI) |
| USDA | U.S. Department of Agriculture |
| USDI | U.S. Department of the Interior |
| USDW | Underground Source of Drinking Water |
| USFS | U.S. Forest Service (USDA) |
| USFWS | U.S. Fish and Wildlife Service (USDI) |
| USGS | U.S. Geological Survey (USDI) |
| USRS | U.S. Reclamation Service (now USBR) |
| UV | Ultraviolet Radiation |
| VOC | Volatile Organic Carbon |
| VOCs | Volatile Organic Chemicals |
| VRM | Visual Resource Management |
| WAVE | Water Alliances for Voluntary Efficiency (EPA) |
| WCWCD | Washoe County Water Conservation District [Nevada] |
| WDV | Water Dilution Volume |
| WET | Water Education for Teachers |
| Wh | Watt-Hour |
| WHPA | Wellhead Protection Area |
| WLA | Wasteload Allocation |
| WMA | Wildlife Management Area (NDOW/DCNR) |
| WPA | Watershed Protection Approach (EPA) |
| WRC | Water Resources Center (DRI) |
| WRD | Water Resources Division (USGS) |
| WRID | Walker River Irrigation District [Nevada] |
| WSA | Wilderness Study Area |
| ZID | Zone of Initial Dilution |
| ZOC | Zone of Contribution |
| ZOI | Zone of Influence |
| ZOT | Zone of Transport |
| ZWA | Zonal Wind Anomaly (ENSO) |