Data and Mapping Tools for NPDES Permittees

National Oceanic and Atmospheric Administration (NOAA) Atlas

NOAA Atlas provides precipitation frequency estimates and associated information. NOAA Atlas 15, currently being updated, will be the first iteration that will (1) develop precipitation frequency estimates for the entire United States and its territories, and (2) update the NOAA Atlas 14 precipitation frequency standard while accounting for changing conditions.

FEMA's Flood Mapping Tools

Various flood mapping tools use observed data to help communities better understand their level and type of flood risk through geographic information system (GIS) data layers. Examples include the National Flood Hazard Layer and the National Risk Index. To assist federal agencies, non-federal partners, and grantees of federal funding, FEMA launched the Federal Flood Standard (FFRMS) Support Tool to assess if projects are located in a floodplain and their vulnerability to future flooding scenarios.

Locating and Selecting Scenarios Online (LASSO)

Developed by EPA, Locating and Selecting Scenarios Online (LASSO) helps users to get information on annual precipitation, temperature, etc.

National Water Information System

National Water Information System is a publicly available portal in which users can access data on current and historical stream levels, stream flow, reservoir and lake levels, surface water quality, and rainfall from USGS.

Sea Level Rise Viewer

Sea Level Rise Viewer is a mapping tool developed by NOAA that visualizes sea level rise and coastal flooding scenarios.

Hydrologic and Water Quality System (HAWQS)

Hydrologic and Water Quality System (HAWQS) is a web-based, interactive water quantity and quality modeling system to simulate the effect of management practices on water quality. HAWQS substantially enhances the usability of Soil and Water Assessment Tool (SWAT), its core modeling engine, to an extensive array of crops, soils, natural vegetation types, land uses, and scenarios for hydrology and the water quality parameters such as sediment, pathogens, nutrients, biological oxygen demand, dissolved oxygen, pesticides, and water temperature. HAWQS has interactive web interfaces and maps; pre-loaded input data; outputs that include tables, charts, and raw output data; a user guide, and online development, execution, and storage of a user's modeling projects.

National Stormwater Calculator

National Stormwater Calculator estimates the annual amount of stormwater runoff from a specific location anywhere in the United States. Estimates are based on local soil conditions, land cover, and historic rainfall records. The calculator includes changes in seasonal precipitation levels, the effects of more frequent high-intensity storms, and changes in evaporation rates based on validated Intergovernmental Panel (IPCC) scenarios. Users can enter any U.S. location and select different scenarios to learn how specific management and design approaches can prevent pollution.

Storm Water Management Model (SWMM)

Storm Water Management Model (SWMM) is used for planning, analysis and design related to stormwater runoff, combined and sanitary sewers, and other drainage systems in urban areas. There are many applications for drainage systems in non-urban areas as well. The Storm Water Management Model Adjustment Tool (SWMM-CAT) is an add-in tool to SWMM. It is a simple to use software utility that allows future projections to be incorporated into the Storm Water Management Model. SWMM accepts monthly adjustment factors for time series that could represent the potential impact of future conditions and provides a set of location-specific adjustments.