Methods

Drinking Water Treatment and Analysis

• Biological Treatment Process for the Removal of Ammonia from a Small Drinking Water System from Pilot- to Full-Scale 
  This engineering design and operation document describes the operation and treatment effectiveness of a small, full-scale biological ammonia removal drinking water treatment plant. The treatment plant engineering design criteria and operating conditions are presented, and development of the project from pilot- to full-scale is discussed. Lastly, lessons learned from the project, and future considerations when designing and operating biological treatment systems for ammonia reduction are presented.
• Drinking Water Methods
  Residues of unregulated contaminants may be present in drinking water, however little is known about their prevalence in the environment. To protect human health, EPA scientists have developed a number of methods to detect unregulated contaminants.
• Microbiological Methods and Online Publications (Bacteria, Protozoans, Viruses, and Coliphage)
  EPA scientists have developed a variety of methods to detect, characterize and study bacteria, protozoans, viruses and coliphage. These methods are used by EPA and state and regional water quality managers to protect human health by keeping drinking water and recreational water safe.
• Removal of Fluoride from Drinking Water Supplies by Activated Alumina
  This design manual is an update to the 1984 version by the same title. It provides an in-depth presentation of the steps required to design and operate a fluoride removal plant using activated alumina, which is a reliable and cost-effective process for treating excess fluoride from drinking water supplies.
• Standard Test Methods for Perfluorinated Compounds (PFC)
  Method 537 is currently used only for drinking water samples. Although nationally approved methods for measuring PFCs in non-drinking water samples are not yet available, the following consensus organization methods are provided by the American Society for Testing and Materials (ASTM): (ASTM D7968) Standard Test Method for Determination of Perfluorinated Compounds in Soil by Liquid Chromatography Tandem Mass Spectrometry, and (ASTM D7979) Standard Test Method for Determination of Perfluorinated Compounds in Water, Sludge, Influent, Effluent and Wastewater by Liquid Chromatography Tandem Mass Spectrometry. 

Environmental Waters

• Microbiological Methods and Online Publications (Bacteria, Protozoans, Viruses, and Coliphage)
  EPA scientists have developed a variety of methods to detect, characterize and study bacteria, protozoans, viruses and coliphage. These methods are used by EPA and state and regional water quality managers to protect human health by keeping drinking water and recreational water safe.
• Biological Methods and Manual Development
  EPA's research in stream and source monitoring indicators includes fish, macroinvertebrates, periphyton, zooplankton, functional ecosystem indicators, water and sediment toxicity, and fish tissue contaminants. EPA exposure scientists regularly prepare and update field and laboratory protocol and methods manuals. They also provide technical assistance to EPA regions, program offices and states on the implementation and interpretation of these manuals. This website lists currently available manuals and protocols.
• Standard of Practice for Determination of Nonylphenol Polyethoxylates (NPnEO, 3 ≤ n ≤ 18) and Octylphenol Polyethoxylates (OPnEO, 2 ≤ n ≤ 12) in Environmental Waters EXIT
  Nonylphenol (NP) and octylphenol (OP) have been shown to have toxic effects in aquatic organisms. The prominent source of NP and OP is from common commercial surfactants, which are longer chain alkylphenol ethoxylates (APEOs). This practice screens for the longer chain APEOs which may enter sewage treatment plants at elevated levels and may cause violations of permitted discharge concentration of NP. It covers determination of NP and OP polyethoxylates in water by Single Reaction Monitoring Liquid Chromatography/ Tandem Mass Spectrometry using direct injection liquid chromatography and detected with tandem mass spectrometry detection. 
• Standard Test Method for Bisphenol A in Environmental Waters Exit
  The environmental source of BPA is predominantly from the decomposition of polycarbonate plastics and resins, which are used in a wide range of commercial products. BPA has been reported to have adverse effects in aquatic organisms and may be released into environmental waters directly at trace levels through landfill leachate and POTW effluents. This method has been investigated for use with surface water and secondary and tertiary POTW effluent samples therefore, it is applicable to these matrices only.

Wastewater and Water Reuse

• Guidelines for Water Reuse (PDF)
  This manual provides comprehensive, up-to-date national guidance on water reuse regulations and program planning in support of regulations and guidelines developed by states, tribes, and other authorities.
• Standard of Practice for Determination of Nonylphenol Polyethoxylates (NPnEO, 3 ≤ n ≤ 18) and Octylphenol Polyethoxylates (OPnEO, 2 ≤ n ≤ 12) in Environmental Waters EXIT
  Nonylphenol (NP) and octylphenol (OP) have been shown to have toxic effects in aquatic organisms. The prominent source of NP and OP is from common commercial surfactants, which are longer chain alkylphenol ethoxylates (APEOs). This practice screens for the longer chain APEOs which may enter sewage treatment plants at elevated levels and may cause violations of permitted discharge concentration of NP. It covers determination of NP and OP polyethoxylates in water by Single Reaction Monitoring Liquid Chromatography/ Tandem Mass Spectrometry using direct injection liquid chromatography and detected with tandem mass spectrometry detection. 

Models

Drinking Water: Distribution Systems and Security

• EPANET
  EPANET is software that models water distribution piping systems. It performs extended-period simulation of the hydraulic and water quality behavior within pressurized pipe networks. EPANET's user interface provides a visual network editor that simplifies the process of building piping network models and editing their properties and data.
• EPANET – Multi-Species eXtension (MSX)
  EPANET is used in homeland security research to model contamination threats to water systems. Historically, EPANET has been limited to tracking the dynamics of a single chemical transported through a network of pipes and storage tanks, such as a fluoride used in a tracer study or free chlorine used in a disinfection decay study. EPA released a new extension to EPANET called EPANET-MSX that allows for the consideration of multiple interacting species in the bulk flow and on the pipe walls. This capability has been incorporated into both a stand-alone executable program as well as a toolkit library of functions that programmers can use to build customized applications.
• EPANET – Real-Time eXtension (RTX)
  EPANET-RTX is the first open-source set of libraries to extend EPANET’s hydraulic and water quality simulation functionality to include data acquisition and predictive forecasting capabilities.

Drinking Water: Wells and Wellhead Protection

• Capture Zone Analytic Element Model (CZAEM)
  CZAEM is a single-layer model for simulating steady flow in homogeneous aquifers using the Analytic Element Method. It serves as a tool in the wellhead protection decision making process by delineating groundwater capture zones and isochrones of residence times. CZAEM supports a limited number of analytic elements that can accommodate fairly realistic boundary conditions, such as streams, lakes, and aquifer recharge due to precipitation. CZAEM generates output on groundwater capture zones and residence times. The model accurately defines capture zone boundaries by first determining all stagnation points and dividing streamlines in the flow domain.
• Optimal Well Locator (OWL)
  This model evaluates existing monitoring well networks and optimizes the selection of new monitoring well locations.
• Wellhead Analytic Element Model (WhAEM2000)
  WhAEM2000 is a public domain, ground-water flow model designed to facilitate capture zone delineation and protection area mapping in support of Wellhead Protection Programs (WHPP) and Source Water Assessment Planning (SWAP) for public water supplies in the United States.
• Wellhead Protection Area (WHPA) Model
  A semi-analytical ground-water flow simulation program used for delineating capture zones in a wellhead protection area. It is applicable to homogeneous aquifers exhibiting two-dimensional, steady groundwater flow in an areal plane and appropriate for evaluating multiple aquifer types.

Green Infrastructure and Stormwater Management

• Green Infrastructure Flexible Model (GIFMod) EXIT
  GIFMod is an open-source framework for modeling urban stormwater and agricultural green infrastructure practices. It allows users to build conceptual models of green infrastructure practices to predict their hydraulic and water quality performance under given weather scenarios. It also allows for interpreting the field and lab data collected by the researchers via its deterministic and probabilistic inverse modeling capabilities.
• Infiltration Models
  This site presents a compilation of simple infiltration models for quantifying the rate of water movement. A great majority of the compiled models are based on widely-accepted concepts of soil physics. These models, represented by simple mathematical expressions, can be readily implemented in a spreadsheet environment. Proper use of these models should provide a rational and scientific basis for remedial decision-making related to soil contaminant levels.
• National Stormwater Calculator with Climate Scenarios (SWC)
  SWC is a desktop application designed to help support local, state, and national stormwater management objectives using GI practices. The primary focus of the SWC is to inform site developers on how well they can meet a desired stormwater retention target, but it can also be used by landscapers and homeowners. In January 2014, it was updated to include the ability to analyze different future climate change scenarios. Users can apply these different scenarios to determine how well GI increases the resiliency of stormwater management approaches to a changing climate. The SWC is now a resource for LEED Project Credit 16 (Rainwater Management) certification by the U.S. Green Building Council for projects that are designed to reduce runoff volume and improve water quality of a site.
• Storm Water Management Model (SWMM)
  SWMM is a software application that is used widely throughout the world for large-scale planning, analysis, and design related to stormwater runoff, combined and sanitary sewers, and other drainage systems in urban areas –although there are many applications for drainage systems in non-urban areas as well. It allows users to represent combinations of green infrastructure practices to determine their effectiveness in managing runoff. SWMM was developed to help support local, state, and national stormwater management objectives to reduce runoff through infiltration and retention.
• Storm Water Management Model - Climate Adjustment Tool (SWMM-CAT)
  SWMM CAT (added to SWMM in 2014) is a simple to use software utility that allows future climate change projections to be incorporated into SWMM. It allows SWMM to accept monthly adjustment factors for time series that could representing the potential impact of future changes in climatic conditions. SWMM-CAT provides a set of location-specific adjustments that derived from global climate change models run as part of the World Climate Research Programme (WCRP) Coupled Model Intercomparison Project Phase 3 (CMIP3) archive. 
• System for Urban Stormwater Treatment and Analysis IntegratioN (SUSTAIN)
  SUSTAIN is a decision support system that assists stormwater management professionals with developing and implementing plans for flow and pollution control measures to protect source waters and meet water quality goals. It allows watershed and stormwater practitioners to develop, evaluate, and select optimal best management practice combinations at various watershed scales based on cost and effectiveness. 
• Visualizing Ecosystem Land Management Assessments (VELMA) Model
  VELMA can be used to help improve the water quality of streams, rivers, and estuaries by making better use of both natural and engineered green infrastructure to control loadings from nonpoint sources of pollution. It is designed to help users assess green infrastructure options for controlling the fate and transport of water, nutrients, and toxics across multiple spatial and temporal scales for different ecoregions and present and future climates.

Fate, Transport, and Exposure

• AQUATOX
  AQUATOX is a simulation model for aquatic systems. AQUATOX predicts the fate of various pollutants, such as nutrients and organic chemicals, and their effects on the ecosystem, including fish, invertebrates, and aquatic plants. This model is a valuable tool for ecologists, biologists, water quality modelers, and anyone involved in performing ecological risk assessments for aquatic ecosystems.
• Better Assessment Science Integrating Point & Non-Point Sources (BASINS)
  BASINS is a multipurpose environmental analysis system designed to help regional, state, and local agencies perform watershed- and water quality-based studies. It was developed to assist in watershed management and TMDL development by integrating environmental data, analysis tools, and watershed and water quality models. A geographic information system (GIS) organizes spatial information so it can be displayed as maps, tables, or graphics. Through the use of GIS, BASINS has the flexibility to display and integrate a wide range of information (e.g., land use, point source discharges and water supply withdrawals) at a scale chosen by the user. (See also: BASINS Climate Assessment Tool and BASINS and Water Erosion Prediction Project Climate Assessment Tools) 
• Bioaccumulation in Aquatic Systems Simulator (BASS)
  BASS is a model that simulates population and bioaccumulation dynamics of age-structured fish communities. While BASS was designed to investigate bioaccumulation of chemicals within community or ecosystem contexts, it also allows EPA to evaluate various dimensions of fish health associated with non-chemical stressors. Accurate bioaccumulation estimates help predict realistic dietary exposures to humans and fish-eating wildlife.
• CHEMFLO™-2000: Interactive Software for Simulating Water and Chemical Movement in Unsaturated Soils
  CHEMFLO-2000 enables users to simulate water movement and chemical fate and transport in vadose zones. The software can be used to assist regulators, environmental managers, consultants, scientists, and students in understanding unsaturated flow and transport processes. Water movement and chemical transport are modeled using the Richards and the convection-dispersion equations, respectively. The equations are solved numerically using the finite differences approach. 
• EPA Center for Exposure Assessment Modeling (CEAM)
  CEAM provides proven predictive exposure assessment techniques for aquatic, terrestrial, and multimedia pathways for organic chemicals and metals. CEAM houses models in the follwoing categories: groundwater, surface water, food chain, multimedia, and Total Maximum Daily Loads (TMDLs).
• Exposure Analysis Modeling System (EXAMS)
  EXAMS is an interactive software application for formulating aquatic ecosystem models and rapidly evaluating the fate, transport, and exposure concentrations of synthetic organic chemicals including pesticides, industrial materials, and leachates from disposal sites.
• Infiltration Models
  This site presents a compilation of simple infiltration models for quantifying the rate of water movement. A great majority of the compiled models are based on widely-accepted concepts of soil physics. These models, represented by simple mathematical expressions, can be readily implemented in a spreadsheet environment. Proper use of these models should provide a rational and scientific basis for remedial decision-making related to soil contaminant levels.
• Mercury Geospatial Assessments for the New England Region (MERGANSER)
  MERGANSER relates atmospheric mercury deposition and lake and watershed characteristics to Hg concentrations in fish and fish-eating wildlife (common loons). The tool provides predicted mercury levels in fish and loons via a web-based interactive tool for 4,404 lakes in New England. States can use MERGANSER to assess the risk of Hg contamination in fish and loons throughout New England and to help plan Hg-pollution reduction efforts.
• Multimedia Exposure Assessment Model (MULTIMED)
  MULTIMED simulates the movement of contaminants leaching from a waste disposal facility. The model consists of a number of modules which predict concentrations at a receptor due to transport in the subsurface, surface air, or air. To enhance the user-friendly nature of the model, separate interactive pre- and post-processing programs allow the user to create and edit input and plot model output.
• Pesticide Analytical (PESTAN) Model
  PESTAN is used to estimate the vertical migration of dissolved organic solutes through the vadose zone to groundwater. Estimates are based on a closed-form analytical solution of the advective-dispersive-reactive transport equation. The model is intended for use in conducting initial screening assessments of the potential for contamination of ground-water from currently registered pesticides and those submitted for registration.
• Two-Dimensional Subsurface Flow, Fate and Transport of Microbes and Chemicals (2DFATMIC) Model
  The 2DFATMIC Model simulates subsurface flow, fate, and transport of contaminants that are undergoing chemical or biological transformations. This model is applicable to transient conditions in both saturated and unsaturated zones.
• Three-Dimensional Subsurface Flow, Fate and Transport of Microbes and Chemicals (3DFATMIC) Model
  The 3DFATMIC Model simulates subsurface flow, fate and transport of contaminants that are undergoing chemical or biological transformations. The model is applicable to transient conditions in both saturated and unsaturated zones.
• Virus Fate and Transport (Virulo) Model
  Virulo is a probabilistic screening model for predicting leaching of viruses in unsaturated soils. It employs Monte Carlo methods to generate ensemble simulations of virus attenuation due to physical, biological, and chemical factors. The model generates a probability of failure to achieve a user-chosen degree of attenuation. Virulo can be used based on limited information such as boring logs, climate data, and soil survey reports for a particular site of interest.

Contaminants and Remediation

• BIOCHLOR, Natural Attenuation Decision Support System
  BIOCHLOR is a screening model that simulates remediation by natural attenuation of dissolved solvents at chlorinated solvent release sites. It has the ability to simulate one-dimensional advection, three-dimensional dispersion, linear adsorption, and biotransformation via reductive dechlorination. Reductive dechlorination is assumed to occur under anaerobic conditions and dissolved solvent degradation is assumed to follow a sequential first-order decay process.
• BIOPLUME II 
  BIOPLUME II is a simulation that computes concentrations of dissolved hydrocarbon under the influence of oxygen-limited biodegradation in an aquifer. The model solves the solute transport equation for both hydrocarbon and oxygen, assumes an instantaneous reaction between oxygen and hydrocarbon, and combines the two plumes using the principle of superposition. The program can simulate slow hydrocarbon plumes undergoing biodegradation and can simulate in situ biorestoration schemes such as the injection of oxygenated water. Moreover, the model can simulate re-aeration and anaerobic biodegradation as a first-order decay in hydrocarbon concentrations.
• BIOPLUME III
  BIOPLUME III program is a two-dimensional, finite difference model for simulating the natural attenuation of organic contaminants in ground water due to the processes of advection, dispersion, sorption, and biodegradation. The model simulates the biodegradation of organic contaminants using a number of aerobic and anaerobic electron acceptors: oxygen, nitrate, iron (III), sulfate, and carbon dioxide.
• BIOSCREEN: Natural Attenuation Decision Support System
  BIOSCREEN is a screening model that simulates remediation through natural attenuation of dissolved hydrocarbons at petroleum fuel release sites. It is designed to simulate biodegradation by both aerobic and anaerobic reactions. BIOSCREEN will allow ground water remediation managers to identify sites where natural attenuation is most likely to be protective of human health and the environment. It will also allow regulators to carry out an independent assessment of treatability studies and remedial investigations that propose the use of natural attenuation.
• Environmental Fluid Dynamics Code (EFDC)
  EFDC is a multifunctional surface water modeling system, which includes hydrodynamic, sediment-contaminant, and eutrophication components. EFDC has been applied to over 100 water bodies including rivers, lakes, reservoirs, wetlands, estuaries, and coastal ocean regions in support of environmental assessment and management and regulatory requirements. 
• FOOTPRINT: A Screening Model for Estimating the Area of a Plume Produced From Gasoline Containing Ethanol
  FOOTPRINT is a simple, user-friendly screening model used to estimate (in groundwater) the length and surface area of benzene, toluene, ethylbenzene, and xylene (BTEX) plumes produced from a gasoline spill that contains ethanol. Ethanol has a potential negative impact on the natural biodegradation of BTEX compounds in groundwater. The primary objective of the software is to predict the increase in surface area of the plume of BTEX compounds or any other chemical of concern due to the presence of ethanol in groundwater.
• Hydrocarbon Spill Screening Model (HSSM)
  Hydrocarbon Spill Screening Model (HSSM), simulates flow of the light nonaqueous-phase liquid (LNAPL) transport of a chemical constituent of the LNAPL from the surface to the water table, radial spreading of the LNAPL at the water table, and dissolution and aquifer transport of the chemical constituent. The HSSM model is one-dimensional in the vadose zone, radial in the capillary fringe, and two-dimensional in the vertically averaged analytical solution of the advection dispersion equation in the saturated zone. The model is based on the KOPT, OILENS and TSGPLUME models. The model is also available as HSSM-DOS and HSSM en Español.
• Hydrological Simulation Program - FORTRAN (HSPF)
  HSPF is a comprehensive package for simulation of watershed hydrology and water quality for both conventional and toxic organic pollutants. HSPF incorporates watershed-scale ARM and NPS models into a basin-scale analysis framework that includes fate and transport in one dimensional stream channels. It is the only comprehensive model of watershed hydrology and water quality that allows the integrated simulation of land and soil contaminant runoff processes with In-stream hydraulic and sediment-chemical interactions.
• MINTEQA2: Geochemical Equilibrium Speciation Model
  MINTEQA2 is a equilibrium speciation model that can be used to calculate the equilibrium composition of dilute aqueous solutions in the laboratory or in natural aqueous systems. The model is useful for calculating the equilibrium mass distribution among dissolved species, adsorbed species, and multiple solid phases under a variety of conditions including a gas phase with constant partial pressures.
• MOFAT: A Two-Dimensional Finite Element Program for Multiphase Flow and Multicomponent Transport
  MOFAT is a two-dimensional, finite element model for simulating coupled multiphase flow and multi-component transport in planar or radically symmetric vertical sections. MOFAT evaluates flow and transport for water, nonaqueous-phase liquid (NAPL), and gas. The program also can be used when gas or NAPL phases are absent in part or from all of the domain. The flow module can analyze two-phase flow of water and NAPL in a system of constant gas pressure, or explicit three phase flow of water. The transport module can accommodate up to five components, partitioning among water, NAPL, gas, and solid phases, assuming local equilibrium inter-phase mass transfer or first-order kinetically controlled mass transfer.
• Nonaqueous Phase Liquid (NAPL) Simulator
  This model simulates the contamination of soils and aquifers that results from the release of organic liquids, commonly referred to as nonaqueous-phase liquids (NAPLs). The simulator is applicable to three interrelated zones: a vadose zone that is in contact with the atmosphere, a capillary zone, and a water-table aquifer zone. Three mobile phases are accommodated: water, NAPL, and gas. The three-phase k-S-P sub-model accommodates capillary and fluid entrapment hysteresis. NAPL dissolution and volatilization are accounted for through rate-limited mass transfer sub-models.
• Remediation Evaluation Model for Chlorinated Solvents (REMChlor)
  This model simulates the transient effects of groundwater source and plume remediation. This is a contaminant source model based on a power-function relationship between source, mass, and discharge. It can consider partial source remediation at any time after release. The source model is a time-dependent, mass-flux boundary condition to the analytical plume model (one-dimensional flow), which simulates first-order sequential decay and production of several species. This model also calculates cancer risks posed by carcinogenic species.
• Remediation Evaluation Model for Fuel Hydrocarbons (REMFuel)
  REMfuel is n analytical solution for simulating the transient effects of groundwater source and plume remediation for fuel hydrocarbons. REMFuel can also simulate zero order or Monod's kinetics for decay of fuel components in the plume. The decay rates and other reaction coefficients are variable functions of time and distance in the plume. This approach allows for flexible simulation of enhanced plume remediation that may be temporary in time, limited in space, and which may have different effects on different contaminant species in the plume.
• Regulatory and Investigative Treatment Zone (RITZ) Model
  RITZ is a screening model for simulation of unsaturated zone flow and transport of oily wastes during land treatment. RITZ was developed to help decision makers systematically estimate the movement and fate of hazardous chemicals during land treatment of oily wastes. The model considers the downward movement of the pollutant with the soil solution, volatilization, and loss to the atmosphere and degradation. The model incorporates the influence of oil upon the transport and fate of the pollutant.
• Vadose Zone Leaching (VLEACH) Model
  VLEACH is a one-dimensional, finite difference model for making preliminary assessments of the effects on groundwater from the leaching of volatile, sorbed contaminants through the vadose zone. In an individual run, it can simulate leaching in a number of distinct polygons, which may differ in terms of soil properties, recharge rates, depth of water, or initial conditions. Modeling results in an overall, area-weighted assessment of ground-water impact.

Water Quality: Pathogens and Nutrient Loading

• Virtual Beach (VB)
  VB is a software package designed for developing site-specific statistical models for the prediction of pathogen indicator levels at recreational beaches. It is primarily designed for beach managers responsible for making decisions regarding beach closures due to pathogen contamination. However, others interested in studying relationships between water quality indicators and ambient environmental conditions will find VB useful.
• Water Quality Analysis Simulation Program (WASP)
  WASP is a spatially and temporally dynamic, mechanistic modeling framework that can assist states by simulating solids and contaminants in the surface water and the underlying sediment layers, with flexibility to handle different complexities of such systems as ponds, lakes, streams, rivers and estuaries. WASP has been widely applied in the development of TMDLs. EPA’s Office of Wastewater Management routinely uses this model to address nitrogen (N) and phosphorus (P) loadings.

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Tools

Chemicals

• Toxicity Forecaster (ToxCast)
  ToxCast generates data and predictive models on thousands of chemicals of interest to the EPA, and uses high-throughput screening methods and computational toxicology approaches to rank and prioritize chemicals. It has data on over 1,800 chemicals from a broad range of sources including industrial and consumer products, food additives, and potentially "green" chemicals that could be safer alternatives to existing chemicals. ToxCast screens chemicals in over 700 high-throughput assays that cover a range of high-level cell responses and approximately 300 signaling pathways.

Drinking Water Treatment and Security

• Breakpoint Chlorination Simulator for Drinking Water Systems EXIT
  Although a reasonable reaction scheme that describes inorganic chloramine formation and decay over a range of conditions applicable to drinking water exists, a widely and freely accessible one does not. This web-based application relevant to drinking water practice was developed to assist water utilities in generating chlorine breakpoint curves. The simulator generates two side-by-side breakpoint curves for comparison purposes with user defined conditions. 
• CANARY 
  CANARY software evaluates standard water quality data (e.g., free chlorine, pH, total organic carbon) over time and uses mathematical and statistical techniques to identify the onset of anomalous water quality incidents. Before using CANARY for the first time, historical utility data must be used to determine the natural variation of these water quality parameters. This allows the water utility to adapt CANARY to work accurately at multiple locations within the water distribution system and helps utility operators to understand the expected false alarm rates associated with CANARY and contamination incident detection. 
• Chloramine Formation and Decay Simulator for Drinking Water Systems EXIT
  Although a reasonable reaction scheme that describes inorganic chloramine formation and decay over a range of conditions applicable to drinking water exists, a widely and freely accessible one does not. This web-based application relevant to drinking water practice was developed to simulate inorganic chloramine formation and subsequent stability, including a simple inorganic chloramine demand reaction for organic matter. It provides two side-by-side simulations and associated graphs to allow comparison of input choices on chloramine formation and decay. 
• Threat Ensemble Vulnerability Assessment – Sensor Placement Optimization Tool (TEVASPOT) Graphical User Interface
  TEVA-SPOT is used by water utilities to optimize the number and location of contamination detection sensors so that economic and/or public health consequences are minimized. It is interactive, allowing a user to specify the minimization objective and specify constraints. Installation and maintenance costs for sensor placement can also be factored into the analysis.

Ecosystem Services and Restoration

• Causal Analysis/Diagnosis Decision Information System (CADDIS)
  CADDIS is a web-based technical support system for implementing the stressor identification process for determining environmental causes. Biological indices are the principal monitoring tool for evaluating the biological condition of water bodies in all 50 states, many territories and tribal lands. Yet when a biological assessment indicates a problem, it may not be readily apparent what caused the problem. CADDIS provides states a causal assessment framework by which data and other information are organized and evaluated, using quantitative and logical techniques, to determine the likely cause of an observed condition needed to identify appropriate remediation or restoration actions. 
• EPA H2O
  EPA H2O is a desktop GIS based decision support tool for assessing the provision of ecosystem services under different land use scenarios. Users can explore the spatial arrangement of ecosystem goods and services at regional to local scales, complete spatial queries along hydrological networks, and generate customized reports for scenario comparisons, all to gain a better understanding of where ecosystem services are produced and how land use change might affect future production. This tool can be used by any community as long as they can develop their local database. States can generate pdf summary reports of what is in both an area of interest and areas upstream or connected via transportation network, compare different alternative future land use scenarios for an area, and generate custom designed scenarios including changing the placement and shape of land use parcels as well as modifying the monetary value benefit functions.
• Rapid Benefit Indicators (RBI) Approach
  The RBI approach is an easy-to-use process for assessing restoration sites using non-monetary benefit indicators. It uses readily-available data to estimate and quantify benefits to people around an ecological restoration site. Whether you are a federal, state, or local manager, or a member of an interest group or funding organization, this simple yet powerful site analysis will allow you and your stakeholders to systematically and equitably incorporate social benefits in restoration decisions.

​Geostatistical Analysis

• Geostatistical Environmental Assessment (GEOEAS) 
  GEOEAS is a collection of interactive software tools for performing two-dimensional geostatistical analyses of spatially distributed data. The principal function of the package is the production of grids and contour maps of interpolated (kriged) estimates from sample data. GEOEAS can produce data maps, univariate statistics, scatter plots/linear regression, and variogram computation and model fitting.
• Geostatistical Software Package (GEOPACK)
  GEOPACK is a comprehensive geostatistical software package that allows both novice and advanced users to undertake geostatistical analyses of spatially correlated data. It allows users to incorporate additional programs at a later date without having to alter previous programs or recompile the entire system.

Green Infrastructure and Stormwater Management 

• Green Infrastructure Modeling Toolkit
  This toolkit contains five EPA green infrastructure models and tools, along with manuals, a summary video, facts sheets, and a green infrastructure brochure. It can be used as a teaching tool and as a quick reference resource for use by planners and developers when making green infrastructure implementation decisions, and can also be used for low impact development design competitions.  
• Green Infrastructure Wizard (GIWiz)
  GIWiz is an interactive web application that provides users with customized reports containing the EPA tools and resources they select, direct links, and overview information about each.
• Retention Curve (RETC) Computer Program
  RETC is a program for analyzing the hydraulic conductivity properties of unsaturated soils. The parametric models of Brooks-Corey and van Genuchten are used to represent the soil water retention curve. The theoretical pore-size distribution models of Mualem and Burdine predict the unsaturated hydraulic conductivity function. The simulation can be generated from observed soil water retention data, assuming that one observed conductivity value (not necessarily at saturation) is available. The program also permits users to fit analytical functions simultaneously to observed water retention and hydraulic conductivity data.
• Sanitary Sewer Overflow Analysis and Planning (SSOAP) Toolbox
  SSOAP is a suite of computer software tools used for the quantification of rainfall-derived infiltration and inflow and capacity analysis and condition assessment of sanitary sewer systems. This toolbox includes EPA’s Storm Water Management Model Version 5 (SWMM5) for performing dynamic routing of flows through the sanitary sewer systems.
• Watershed Management Optimization Support Tool (WMOST)
  WMOST is a software application designed to facilitate integrated water resources management across wet and dry climate regions. It allows water resources managers and planners to screen a wide range of practices across their watershed or jurisdiction for cost-effectiveness and environmental and economic sustainability. WMOST allows users to select up to fifteen stormwater management practices, including traditional grey infrastructure, green infrastructure, and other low impact development practices.

Watershed Management

• Automated Geospatial Watershed Assessment Tool (AGWA)
  AGWA is a geographic information systems (GIS) interface designed to help manage and analyze watershed water quantity and quality. Developed by EPA, the U.S. Department of Agriculture, and the University of Arizona, the tool is designed to provide qualitative estimates of runoff and erosion relative to landscape change. 
• Estuary Data Mapper (EDM)
  EDM is a downloadable application that can help states view and access data for estuary-scale geographical regions of interest. Data types include nitrogen sources and loads for coastal watersheds and estuaries, including atmospheric deposition, point source loads and nonpoint source loads as well as response endpoints, such as seagrass and chlorophyll a.   
• Watershed Deposition Tool (WDT)
  WDT is a software tool for mapping deposition estimates from the Community Multi-scale Air Quality (CMAQ) model to watersheds. It provides users with the linkage of air and water needed for the total maximum daily load (TMDL) and related nonpoint-source watershed analyses. WDT takes gridded atmospheric deposition estimates from CMAQ and allocates them to user-defined hydrologic cataloging units of rivers and streams within a watershed, state or region and provides output as text or shapefiles.
• Watershed Health Assessment Tools Investigating Fisheries (WHATIF)
  WHATIF is software that integrates a number of calculators, tools, and models for assessing the health of watersheds and streams with an emphasis on fish communities in the Mid-Atlantic Highland region.
• Watershed Management Optimization Support Tool (WMOST)
  WMOST is a software application designed to facilitate integrated water resources management across wet and dry climate regions. It allows water resources managers and planners to screen a wide range of practices across their watershed or jurisdiction for cost-effectiveness and environmental and economic sustainability. WMOST allows users to select up to fifteen stormwater management practices, including traditional grey infrastructure, green infrastructure, and other low impact development practices.

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Databases

Chemicals

• Chemical and Product Categories (CPCat) Database
  CPCat is a database containing information mapping more than 43,000 chemicals to a set of terms categorizing their usage or function. The comprehensive list of chemicals with associated categories of chemical and product use was compiled from publically available sources. Unique use category taxonomies from each source are mapped onto a single common set of approximately 800 terms. Users can search for chemicals by chemical name, Chemical Abstracts Registry Number, or by CPCat terms associated with chemicals.

Drinking Water Treatment

• Drinking Water Treatability Database (TDB)
  The TDB presents referenced information on the control of contaminants in drinking water. It allows drinking water utilities, first responders to spills or emergencies, treatment process designers, research organizations, academicians, regulators and others to access referenced information gathered from thousands of literature sources and assembled on one site. Over time, the TDB will expand to include over 200 regulated and unregulated contaminants and their contaminant properties. It includes more than 25 treatment processes used by drinking water utilities. 

Drinking Water and Wastewater Infrastructure

• National Database Structure for Life Cycle Performance Assessment of Water and Wastewater Rehabilitation Technologies (Retrospective Evaluation) (Registration required) Exit
  This database houses performance evaluation data for rehabilitation technologies used in the water and wastewater sectors on a national basis, including additional cured-in-place pipe liner testing. The database will improve the capability of utilities to sustainably manage their aging and deteriorating water distribution, stormwater and wastewater collection systems, and will help increase acceptance of new and innovative technologies by decision makers who adopt, regulate, and design infrastructure technologies. The databases can also assist utilities to more effectively implement comprehensive asset management, provide reliable service to their customers, and meet their Clean Water Act and Safe Drinking Water Act requirements.
• Water Infrastructure Database (WATERiD) Exit
  WATERiD is a database used for helping utilities choose the best pipe rehabilitation, condition assessment, and pipe-location determining technologies for both wastewater conveyance systems and drinking water distribution systems. It includes primary information about individual renewal technologies' cost and performance, case studies for their real world applications, and the list of vendors, consultants, and contractors available for a particular technology on a regional basis. The database allows utilities to input their experiences in these areas for the benefit of other utilities.

Ecosystems and Watersheds

• Freshwater Biological Traits Database (Traits)
  This database contains traits data for 3,857 North American macroinvertebrate taxa, and includes habitat, life history, mobility, morphology and ecological trait data. These data were compiled for a project on climate change effects on river and stream ecosystems.
• Stream-Catchment (StreamCat) Dataset
  StreamCat is an extensive collection of landscape metrics for 2.6 million streams and associated catchments within the conterminous U.S. It includes both natural and human-related landscape features. The data are summarized both for individual stream catchments and for cumulative upstream watersheds. StreamCat data are being utilized to develop national maps of aquatic condition and watershed integrity, and can be used to model and predict reference condition for the National Rivers and Streams Assessment. The data will also be useful to states that are conducting similar assessments.

Green Infrastructure and Stormwater Management

• GeoPlatform Best Management Practice Performance Database
  This database allows users to see how well certain BMPs and low impact development (LID) approaches control stormwater runoff in different parts of the U.S. This web map displays sites where the performance of BMPs and LID approaches for controlling stormwater runoff have been monitored and reported on. Each site also contains a link back to the database where more detailed information on the site and its performance can be found.