Water data sources in the United States

1.7 million sample results for 29 PFAS and lithium from 9,950 public water systems. Ninth data release published August 2025.

Free | National

Effective flood hazard data and HEC-RAS models for NFIP

Free | National flood hazard mapping

Comprehensive groundwater data portal for MODFLOW modeling

Free | Multi-agency groundwater network

National hydrography framework with stream networks and catchments

Free | 27 million flowline features

IDF curves and precipitation frequency estimates for stormwater design

Free | Continental US

The most comprehensive open-source marine microplastics database globally, aggregating data from 33+ peer-reviewed datasets with records dating back to 1972.

Free | Global oceans, 33+ aggregated datasets since 1972

Weekly drought maps with 5-level classification (D0-D4)

Free | Continental United States

National integrated water quality database

Free | 430M+ water result records

Cropland Data Layer for agricultural land use mapping

Free | Continental US annual cropland

Arsenic values in micrograms per liter for groundwater samples from approximately 31,000 wells and springs across 49 US states compiled by USGS, with downloadable Excel, TXT, and...

Free | 49 US states, 31,000 wells and springs

Real-time flood monitoring and streamflow data from 8,700+ sites

Free | 8,700+ monitoring sites nationwide

Real-time and historical groundwater level data

Free | 800,000+ wells monitored

Hydrography shapefiles and DEMs

Free | Vector and raster water datasets

Real-time US water monitoring

Free | 3500+ stations

Irrigation and water management practices data

Free | US agricultural water management

Arizona DWR open data hub providing the Groundwater Site Inventory (GWSI) field-verified well and spring data and Wells-55 registry, downloadable as Shapefile, CSV, KML, GeoJSON...

Free | State (Arizona, USA)

Arizona DWR ArcGIS Open Data portal offering wells, groundwater site inventory (GWSI), water levels, depth-to-water and related water-resource datasets for download and as...

Free | Sub-national

USBR Pacific Northwest network of 90+ automated agricultural weather stations providing crop-specific evapotranspiration summaries and daily ET charts for irrigation water...

Free | Regional

Hydrologic database for water management

Free | 17 western states water projects

High-precision weighing-lysimeter water-balance data (15-minute and daily ET, irrigation, precipitation, dew/frost) for maize, sunflower and winter wheat at the USDA-ARS Bushland...

Free | Texas High Plains

California water resources data

Free | California state

California State Water Resources Control Board PFAS monitoring data for public water systems, including PFOA, PFOS, PFHxS, and other analytes.

Free | California State

Sentinel-1 InSAR vertical ground displacement measurements across 200+ California groundwater basins from 2015-2022 at 100m grid resolution for SGMA groundwater sustainability...

Free | 200+ California groundwater basins, 2015-2022

Microplastic and microparticle data from surface water sampling in San Francisco Bay and adjacent National Marine Sanctuaries.

Free | San Francisco Bay and adjacent National Marine Sanctuaries

Sentinel-1 InSAR-derived vertical ground displacement over 200+ California groundwater basins (2015-2022) processed for the Department of Water Resources, used to track...

Free | Subnational

California DWR Sustainable Groundwater Management Act data viewer providing groundwater datasets organized by SGMA and Groundwater Sustainability Plan requirements to support GSP...

Free | Sub-national

California DWR interactive dashboards delivering the most recent statewide groundwater information filterable by address, county, basin, well depth and time period.

Free | Sub-national

CDC's national wastewater surveillance program tracking SARS-CoV-2, mpox, influenza, RSV, and other pathogens across 1,400+ U.S.

Free | National

California Department of Water Resources network of 145+ agricultural weather stations providing daily reference evapotranspiration (ETo), Spatial CIMIS statewide ETo, and weather...

Free | Regional

Daily grass-reference evapotranspiration (ETo) maps for California at 2 km resolution, plus weather-station ETo from 145+ agricultural weather stations.

Free | California

Colorado Division of Water Resources clearinghouse (CDSS) for water data including streamflow, diversions, groundwater water levels, well permits and water-rights administrative...

Free | Sub-national

Colorado Division of Water Resources Decision Support System REST API serving HydroBase data: real-time and historical streamflow, surface water and groundwater station readings...

Free | State-wide (Colorado)

Colorado's Decision Support Systems database containing water rights, structures, diversion records, irrigated lands, streamflow, and reservoir storage data for Colorado, with...

Free | Regional

Connecticut DEEP Water Monitoring Group statewide inland water-quality data (physical/chemical, biological, habitat) with availability listings and links to download...

Free | Connecticut

Pacific Northwest National Laboratory geo-processed global dataset (2024) of aquifer properties on a 0.5-degree grid: depth to groundwater, aquifer thickness, porosity...

Free | Global

Global database of microplastic concentrations, sizes, shapes, and polymer data for sediments compiled from published literature.

Free | Global with strong US coverage, lakes/rivers/estuaries/harbors/marine

Cloud-based climate and drought monitoring

Free | Daily drought indices

Comprehensive drought data, forecasts, and planning tools

Free | United States

Geospatial boundaries for community water systems covering 80% of all public water users. Version 2 released September 2025.

Free | National

Multi-agency satellite monitoring of cyanobacterial blooms in 2,300+ U.S. lakes using Sentinel-3 OLCI with daily and 7-day composites from 2016 to present. Includes web app and API

Free | 2,300+ U.S. lakes and reservoirs

US Environmental Protection Agency multi-extent interactive environmental map with broad-scale data for the lower 48 states and fine-scale data for selected communities, including...

Free | Lower 48 US states with fine-scale community data

Environmental data service API

Free | Multiple EPA databases

Public water system compliance data

Free | 150,000 public water systems

Total Maximum Daily Load resources and tools

Free | National TMDL information

Universal water quality data format

Free | 1500+ agencies contributing

Water pollution hotspot visualization system

Free | National water quality indicators

US water geospatial datasets

Free | National water geospatial data

Watershed assessment and environmental tracking

Free | NHDPlus integrated system

Maryland DNR portal serving continuous (15-min) tidal water quality monitoring: water temperature, salinity, dissolved oxygen, pH, turbidity and chlorophyll fluorescence across...

Free | Regional (Maryland / Chesapeake Bay)

Common Land Unit agricultural training data

Registration Required | Farm-level agricultural data

Repository of effective hydraulic models used in flood studies

Free | NFIP hydraulic models

Florida Department of Environmental Protection geospatial open data portal offering environmental monitoring, water resources, watershed and hydrography datasets for download and...

Free | Sub-national

NOAA-hosted ArcGIS Hub aggregating global and continental drought monitoring layers using a bottom-up comparison of national/continental drought assessments, with maps, indicators...

Free | Global

EPA-mandated public water system lead service line inventories published under the Lead and Copper Rule Revisions (LCRR), aggregated via state portals and federal data releases...

Free | National (public water systems)

USGS groundwater atlas and aquifer maps

Free | Regional groundwater studies

RESTful National Hydrography API

Free | National Hydrography dataset

IDWR Landsat-based METRIC evapotranspiration maps for Idaho agricultural fields across many years, used for water-rights administration and irrigation water accounting, available...

Free | Regional

Idaho DWR ArcGIS Hub providing free public water data, maps and resources covering water rights, river flow, water leases, wells and spatial datasets for download.

Free | Sub-national

Idaho Department of Water Resources online research portal for water rights, river flow, water measurement and agricultural water-use information, with mapping and downloadable...

Free | Idaho

Imperial Irrigation District (California) water department providing information and data on Colorado River water deliveries, canal/reservoir facilities, and water conservation...

Free | Regional

Iowa Department of Natural Resources public portal to retrieve water-quality monitoring and assessment data collected by the DNR Water Quality Monitoring and Assessment Section.

Free | Sub-national

Stream chemistry and discharge measurements used to calculate inorganic carbon flux from streams near Juneau, Alaska, published in the USDA National Agricultural Library Ag Data...

Free | Juneau, Alaska

Lake Champlain Basin Program describing and linking long-term water quality and biological monitoring (15 lake stations, bi-weekly) plus Lay Monitoring Program data: total...

Free | Regional (Lake Champlain basin)

USGS Landsat Collection 2 Level-2 surface reflectance products enable computation of water indices (NDWI, MNDWI) for mapping surface water bodies from 1984 to present at 30m...

Free | Global

Lower Colorado River Authority network of more than 275 automated gauges across the lower Colorado River basin in Texas, providing near-real-time streamflow, river stage...

Free | 275+ gauges, lower Colorado River basin (Texas)

Geological and lithologic data for groundwater modeling

Free | National geological database

Maine DEP Environmental and Geographic Analysis Database storing site, surface water, groundwater and biological sampling data; statewide environmental sampling datasets provided...

Free | Maine

Maryland DNR portal for tidal water-quality monitoring data, continuous monitoring and data visualizations for the Chesapeake Bay and tributaries, with downloads.

Free | Maryland / Chesapeake Bay

Maryland DNR tidal water-quality monitoring portal for Chesapeake Bay providing 15-minute continuous monitoring data since 2001, monthly Dataflow surface-mapping, and long-term...

Free | Regional

Michigan Dept. of Environment, Great Lakes and Energy GIS hub with water-quality monitoring, surface water and groundwater datasets and mapping applications, downloadable in open...

Free | Michigan

State-level PFAS sampling database from Michigan covering public water supplies, surface water, groundwater, fish tissue, and contamination sites.

Free | Michigan State

Minnesota DNR portal for selecting groundwater observation wells, viewing hydrographs and well metadata, and downloading time-series water-level data in XLSX or CSV.

Free | Minnesota

Interactive dashboard for PFAS monitoring results in Minnesota public water systems and private wells, including exceedances of state health-based guidance values and the federal...

Free | Minnesota State

Searchable portal for 4,500+ Minnesota lakes/rivers offering lake surveys, depth maps and downloadable reported lake water-level (elevation) time series in dBase or ASCII.

Free | Minnesota

Joint DNR and Pollution Control Agency program offering real-time, preliminary and historical streamflow plus water quality and climatology data from KISTERS WISKI time-series...

Free | Sub-national

Downloadable GIS dataset of DNR/MPCA cooperative stream gaging station locations for Minnesota, available as File Geodatabase, Shapefile and GeoPackage with web services.

Free | Sub-national

Minnesota DNR lake bathymetric contours and digital elevation models (typically 5 m cells, depth attribute) for thousands of lakes, downloadable via the state geospatial open-data...

Free | Minnesota

Minnesota Geospatial Information Office catalogue of downloadable groundwater GIS layers including bedrock/Quaternary hydrogeology, ground water provinces, County Well Index...

Free | State (Minnesota, USA)

Minnesota PCA surface water data search tool providing water-quality information for specific lakes, rivers and streams across the state, including nutrients, transparency and...

Free | Regional

California irrigation district providing agricultural water service information, Tuolumne River flow and reservoir conditions, and water information links (CIMIS, river flow) for...

Free | Regional

Montana Bureau of Mines and Geology central repository for groundwater data: well-completion reports, up to 60 years of water-level measurements, water-quality reports and...

Free | Sub-national

Standardized water-well records from state agencies

Free | Multi-state well database

NOAA National Estuarine Research Reserve System's data office serving System-Wide Monitoring Program (SWMP) water quality (15-min), nutrient/chlorophyll and meteorological data...

Free | National (US estuaries)

Nevada DWR ArcGIS Hub offering water-resource datasets (well driller reports, hydrographic data) for download in CSV, KML, GeoJSON, GeoTIFF and via GeoServices/WMS/WFS APIs.

Free | Sub-national

Searchable well-log database from the Nevada Division of Water Resources allowing queries by basin, location, work type, use, driller and date, with WGS84 well locations and GIS...

Free | Sub-national

New Mexico Water Data Act portal integrating groundwater and water-rights/use data from OSE, NMED, EMNRD and the Bureau of Geology, served through a catalog and OGC SensorThings...

Free | New Mexico

CKAN-powered open data catalog integrating New Mexico water datasets (water quantity, quality, rights and monitoring) from multiple state providers under the New Mexico Water Data...

Free | Sub-national

New Mexico Water Data Initiative CKAN catalogue entry exposing the USGS National Ground-Water Monitoring Network as a discoverable, queryable dataset for groundwater levels, water...

Free | Subnational

New York State Department of Environmental Conservation stream and lake water-quality monitoring data presented in an interactive map with downloadable data files.

Free | Sub-national

USGS National Hydrography Dataset live ArcGIS REST services exposing waterbody (lake, pond, reservoir) and flowline features for the United States, queryable and downloadable...

Free | United States

Over 40 years (1979-2022) of modeled historical water level and wave data every 500m along the U.S. Atlantic, Caribbean, and Gulf coasts. Released January 2025.

Free | U.S. coastlines

Coastal water feature downloads

Free | NOAA coastal hydrography

National coastal water quality monitoring

Free | US coastal waters

NOAA Great Lakes Environmental Research Laboratory data hub providing long-term Great Lakes water levels (records from 1860), the Great Lakes Water Level Dashboard, GLSEA...

Free | Regional (Great Lakes)

Data collection and distribution system tracking current and historical harmful algal bloom events in the Gulf of Mexico since 2001 with cell counts, environmental data, and...

Free | Gulf of Mexico, 2001-present

Near-real-time satellite-derived harmful algal bloom monitoring for U.S. coastal and Great Lakes regions using Sentinel-3 OLCI and Sentinel-2 MSI imagery

Free | Great Lakes, Gulf of Mexico, U.S. coastal waters

Hydrologic forecasting system

Free | 2.7 million river reaches

Water forecasting and flood prediction

Free | National water prediction network

NOAA S-111 surface water currents dataset on AWS S3 providing gridded current speed and direction forecasts for US coastal and harbor regions in the IHO S-111 HDF5 format.

Free | US coastal waters

Coastal water levels and tidal data for HEC-RAS boundary conditions

Free | 3,000+ water level stations

NC DEQ GIS open data portal hosting Division of Water Resources active ambient monitoring stations and related water datasets, downloadable as GeoJSON/CSV/shapefile.

Free | North Carolina

North Dakota Dept. of Environmental Quality data retrieval and mapping tool to view surface-water stations on a map and download sampling results for lakes, reservoirs, rivers and...

Free | North Dakota

USDA Natural Resources Conservation Service network monitoring soil moisture, precipitation, temperature, and other climate data

Free | United States - 200+ stations nationwide

Snow telemetry and soil climate monitoring

Free | 800+ mountain sites in western US

New York City Department of Environmental Protection dataset of green infrastructure assets: bioswales, rain gardens, green roofs, permeable pavement: deployed across all five...

Free | New York City

Ohio DNR Division of Geological Survey portal serving the Groundwater Observation Well Network via AQUARIUS, allowing users to view and download raw data files and create custom...

Free | Ohio

OWRB groundwater data and maps portal providing groundwater-level monitoring wells and Beneficial Use Monitoring Program data with downloads as geodatabase, shapefile, data table...

Free | Oklahoma

Oregon Water Resources Department portal for near real-time and historical stream stage, discharge and reservoir/lake level data from 200+ WRD gages, with daily and instantaneous...

Free | Sub-national

Tools and methods for calculating pollutant loads

Free | Load estimation methodologies

North American Lake Management Society annual citizen-science program collecting volunteer Secchi-disk water transparency measurements from lakes, rivers, and streams across North...

Free | North American lakes, rivers and streams, 1994-present

USDA Soil Climate Analysis Network of 200+ stations measuring soil moisture and soil temperature at multiple depths, plus weather, focused on agricultural areas of the U.S.

Free | United States

South Dakota DANR application providing groundwater-level readings for state-owned observation wells (1,556 wells across 25 aquifers) with well metadata and aquifer information.

Free | South Dakota

Official environmental database of the South Florida Water Management District providing groundwater and surface water levels, flows, water quality, and atmospheric data...

Free | Sub-national

Hydrologic and geohydrologic data from the Southwest Florida Water Management District (WaterMatters), including well water levels, surface water levels, flows and rainfall...

Free | Sub-national

Southwest Florida Water Management District Environmental Data Portal providing groundwater and surface water levels, flows and water-quality data with site-based access to...

Free | Regional

Shuttle Radar Topography Mission Water Body Dataset providing a comprehensive delineation of ocean, lake, and river shorelines at ~30m resolution derived from the 2000 SRTM radar...

Free | Global

Advanced soil database management and analysis tools

Free | United States

Detailed soil survey data for the United States

Free | United States detailed coverage

State-level hydrogeology and well databases

Free | All 50 states

Generalized soil association map for the United States

Free | United States state-level

DOE/PNNL hydro-economic model and supporting global dataset for evaluating groundwater cost and supply (depletion, lift, extraction cost) across the world's aquifers, with code...

Free | Global

EPA training resources for water quality modeling

Free | Water quality modeling education

Texas Commission on Environmental Quality viewer mapping water-well sampling and monitoring locations from the Texas Water Quality Integrated Report (Clean Water Act 305(b))...

Free | State (Texas, USA)

Texas Commission on Environmental Quality viewer and Integrated Water Districts Database for water-control and improvement districts, irrigation districts and municipal utility...

Free | Texas

Southeast water management data

Free | Tennessee River system

Texas Water Development Board statewide mesonet aggregating weather stations and rain gauges with real-time soil moisture, meteorological, and evapotranspiration-relevant data for...

Free | Regional

Texas Water Development Board 'network of networks' providing real-time and historical soil moisture (at 2/4/8/20 inch depths), soil temperature, evapotranspiration and weather...

Free | Texas

Texas Water Development Board groundwater database (~140,000 well records, water levels, water quality, springs) plus the Submitted Drillers Report database, accessible through...

Free | State-wide (Texas)

EPA tool consolidating green infrastructure datasets, models, and case studies for stormwater management, low-impact development, and urban runoff mitigation.

Free | National

IHS Sanitation Deficiency System (SDS) dataset documenting water, wastewater, and solid waste infrastructure needs for Native American and Alaska Native households: a foundational...

Limited | Tribal lands (national)

US Army Corps of Engineers Corps Water Management System public data dissemination service providing reservoir, river stage, flow and water-control time-series data nationwide via...

Free | National

Corps Water Management System public RESTful API providing time-series reservoir elevations, storage and flow for USACE dams and Section 7 projects nationwide.

Free | United States

US Army Corps of Engineers Detroit District daily water-level reports for Lakes Superior, Michigan-Huron, St.

Free | Laurentian Great Lakes

Corps water control data and historical flow records

Free | Corps projects and studies

US Army Corps of Engineers Jacksonville District water-management dashboard with lake/reservoir elevation, storage and forecast data for Florida and the ACF/Lake Okeechobee system.

Free | Florida / Jacksonville District

Official US Army Corps of Engineers database of all known dams in the United States with over 70 data fields including location, size, purpose, inspection history, and flood...

Free | National (90,000+ dams)

Comprehensive database of over 7,000 levee systems covering 24,000+ miles of levees with condition data, flood risk information, and inspection records

Free | National (7,000+ levee systems)

US Army Corps of Engineers RiverGages portal providing current and historic water-level (SHEF) data for rivers, streams, tributaries and lakes across the central United States.

Free | Regional

US Army Corps of Engineers Sacramento District reservoir water-control data: current and archived levels, storage and flood-control space for Shasta, Oroville, Folsom, Pine Flat...

Free | California / Sacramento District

US Army Corps of Engineers national water data platform with interactive mapping of dams, rivers and streamgages plus water management, resources and quality data.

Free | National

Bureau of Reclamation Lower Colorado region operations hub providing daily reservoir conditions, historical reservoir levels and elevation projections for Lake Mead, Lake Mohave...

Free | Lower Colorado River reservoirs

Crop-specific planting frequency analysis

Free | Major crop frequency mapping

USDA NRCS one-stop portal providing over 100 high-resolution geospatial data layers including soil surveys, hydrography, watershed boundaries, and precipitation data updated weekly

Free | National (100+ data layers)

Comprehensive agricultural statistics database

Free | Complete US agricultural statistics

Soil Survey Geographic Database (SSURGO) with detailed soil properties and interpretations

Free | Continental United States

Plant characteristics and agricultural parameters

Free | Comprehensive plant database

US Fish & Wildlife Service National Wetlands Inventory: 37+ million wetland and deepwater features for the US and territories, downloadable by HUC8 watershed or state in...

Free | United States and territories

Interactive Wetlands Mapper and seamless wetlands data services for the United States, providing on-the-fly viewing plus geospatial download of NWI wetland classification polygons...

Free | United States

NHD replacement shapefile downloads

Free | NHDPlus HR National Release 2

3D Elevation Program high-resolution elevation data

Free | United States expanding coverage

Statistical random-forest models predicting nitrate and arsenic concentrations across 190,600 square miles of basin-fill aquifers in Arizona, California, Colorado, Nevada, New...

Free | Southwestern US: AZ, CA, CO, NV, NM, UT basin-fill aquifers

Best Available Time Series for groundwater levels, displaying groundwater-level trends in the National Groundwater Monitoring Network Data Portal.

Free | National

Ground-Water Vulnerability Assessment model predicting nitrate contamination risk in US groundwater.

Free | United States nationwide: shallow and deep groundwater

Real-time streamgage sensor data

Free | 10,000+ monitoring stations

WRTDS trend analysis dataset

Free | Version 1.1 released March 2025

Quantity and morphology of floating microplastics in 29 Great Lakes tributaries across 6 states with 107 water samples and detailed particle characterization.

Free | 29 Great Lakes tributaries across 6 US states

Assessment of microplastic pollution in streams of the northeastern United States. Fibers composed an average of 71% of all microplastic particles found.

Free | Northeastern US streams, 2017-2018 sampling period

Microplastic quantity, morphology, and polymer identity in water column and surficial sediments of Milwaukee-area streams, Milwaukee Harbor, and Lake Michigan.

Free | Milwaukee-area streams, Milwaukee Harbor, Lake Michigan

Long-term water quality monitoring

Free | 102 surface + 258 groundwater sites

Long-term USGS NAWQA pesticide occurrence data in streams, groundwater, and ambient waters across the U.S., including the Pesticide National Synthesis Project and Regional Stream...

Free | National

USGS National Water-Quality Assessment Project trace element data for U.S. rivers, streams, and aquifers.

Free | National (CONUS)

Annual peak streamflow data for flood frequency analysis

Free | 30,000+ stream gages

USGS nationwide study measuring 32 per- and polyfluoroalkyl substances (PFAS) in tapwater from public and private supplies across the United States, with open sample-level...

Free | National (public + private supplies)

US geological survey research repository

Free | 150+ years of publications

Real-time water quality monitoring network

Free | Nationwide real-time network

Scientific geospatial data services

Free | USGS scientific data repository

Basin characteristics and flow statistics for ungauged streams

Free | All US states with varying parameters

Weekly 1km drought stress model integrating MODIS NDVI satellite observations with climate data and biophysical characteristics for vegetation drought monitoring across the...

Free | Conterminous US, 1km weekly, 2009-present

Real-time and historical water data

Free | National water monitoring network

OpenAPI specification water services

Free | OGC compliant APIs

REST API for hydrological data

Free | Modernized APIs releasing 2025

Water withdrawal and consumption data for flow modifications

Free | County and state estimates

USGS Water Information for SWOT Products application providing access, visualization and explanation of SWOT satellite surface-water hydrology products (river and lake water...

Free | Global

Utah Division of Water Resources ArcGIS Open Data site hosting water-related GIS datasets and interactive maps produced by the Division for public discovery and download.

Free | Sub-national

Vermont Department of Environmental Conservation lakes and ponds monitoring program providing water quality data (total phosphorus, chlorophyll, transparency) from long-term and...

Free | Regional (Vermont)

Virginia DEQ ArcGIS Hub providing direct access to spatial and non-spatial environmental data including water quality monitoring, permits and watershed datasets drawn from the...

Free | Sub-national

Washington State Department of Ecology near real-time monitoring data for streamflow plus dissolved oxygen, temperature, pH and conductivity from automated long-term river and...

Free | Sub-national

Interactive map and information system from Washington Department of Ecology providing water quality data for the state's lakes, rivers, streams and estuaries including 303(d)...

Free | Sub-national

Washington Dept. of Ecology database to search, view and download environmental monitoring data for water, sediment, groundwater, river/stream water quality and streamflow...

Free | Washington State

Texas Water Development Board's single-access-point platform for real-time and historical conditions of 122+ major water-supply reservoirs (level, storage, surface area...

Free | State-wide (Texas)

EPA water quality data download portal

Free | EPA water quality datasets

Wisconsin DNR network reporting well inventory, well construction, sample analytical data and water-level data drawn from several DNR groundwater databases statewide.

Free | Wisconsin

Wisconsin DNR repository of Clean Water Act monitoring data including water/sediment/fish-tissue chemistry, physical and biological (macroinvertebrate, aquatic invasive) data for...

Free | Regional

WSU's network of 550+ agricultural weather stations providing near-real-time weather, soil moisture, reference and crop-specific daily ET estimates, and irrigation scheduling...

Free | Regional

Asia-Pacific Data-Research Center (Univ. of Hawaii) distribution of the CPC Global Unified gauge-based daily precipitation analysis (1979-present, 0.5 degree), accessible via...

Free | 1979-present, 0.5 degree daily

APDRC distribution of the GPCP (Global Precipitation Climatology Project) merged 1-degree daily precipitation analysis, with OPeNDAP and LAS access for global daily rainfall.

Free | 1996-present, 1 degree daily

APDRC serving NOAA-CIRES-DOE Twentieth Century Reanalysis V3 (1836-2015) including surface and convective precipitation rate, via OPeNDAP, ERDDAP and LAS for long-term...

Free | 1836-2015 ensemble

University of Arizona network of automated weather stations providing reference and actual evapotranspiration, heat units, chill hours, and weather data for irrigation and...

Free | Regional

CHIRPS quasi-global 0.05 degree rain-gauge-plus-satellite precipitation, 1981-present, served through the IRI Data Library with on-the-fly subsetting, analysis and multiple...

Free | 50S-50N

Colorado Climate Center network of 90+ research-grade weather stations originally designed to measure reference evapotranspiration near crops, with daily crop-water-use ET reports...

Free | Colorado

Texas Data Repository Dataverse archive of the Center for Space Research GRACE RL06 mascon equivalent-water-height grids, a citable DOI-versioned source for GRACE terrestrial...

Free | Global

National Drought Mitigation Center Drought Risk Atlas providing long-term station-based drought indices (SPI, PDSI, SPEI) and risk statistics with interactive maps and station...

Free | United States

University of Florida IFAS network of agricultural weather stations providing Penman-Monteith reference ET and weather observations with a Report Generator for downloadable CSV...

Free | Regional

NASA-funded experimental near-real-time global flood detection system using TRMM/GPM IMERG precipitation in a 1/8-degree hydrological runoff and routing model (50N-50S).

Free | Global (50N-50S)

Landsat-derived time series of surface area for 6,817 global reservoirs (1984-2015), corrected for cloud and terrain contamination, building on the JRC global surface water...

Free | Global

University of Nebraska regional climate center providing climate and crop water use (ET) data services across a six-state High Plains region including reference ET and crop-stage...

Free | Regional

University of Iowa IIHR real-time water-quality network reporting nitrate, pH, dissolved oxygen, discharge and temperature every 15 minutes across Iowa's rivers and streams, with...

Free | Iowa

Columbia University IRI/LDEO Climate Data Library: hundreds of terabytes of gridded climate datasets (CHIRPS v3, GPCC, CMAP, reanalyses) browsable, analyzable and downloadable...

Free | Multi-dataset, varies

Kansas State University mesonet providing daily grass and alfalfa reference evapotranspiration (ASCE Penman-Monteith) and four-depth soil moisture data for irrigation and crop...

Free | Regional

Open-access research platform integrating compiled limnological water-quality data (chemistry, nutrients, Secchi, chlorophyll) for nearly 480,000 lakes across the conterminous...

Free | National

Benchmark dataset harmonizing 500M+ lake water quality observations across 17 variables (chlorophyll a, DO, total phosphorus, DRP, phycocyanin, temperature, fDOM) from 21 US lakes...

Free | Regional (US lakes)

NADA tree-ring reconstructed PDSI drought atlas served through the IRI/LDEO Climate Data Library, which exposes the gridded data for visualization, subsetting and download in...

Free | North America

Web application for instrumental and tree-ring reconstructed Palmer Drought Severity Index over Mexico, allowing users to generate maps and time series.

Free | Mexico

University of Minnesota satellite-derived lake water-clarity and trophic-state browser for thousands of Minnesota lakes, mapping inland-water quality over multiple decades from...

Free | Minnesota

University of Nebraska School of Natural Resources downloadable database of wells and water-level data from the statewide Groundwater-Level Monitoring Program covering 24,000+...

Free | Sub-national

Tree-ring reconstructed Palmer Drought Severity Index over North America spanning centuries, with a web application to create maps and time series of instrumental and...

Free | North America

Oklahoma Mesonet network of 120 environmental monitoring towers providing weather, soil moisture, reference and crop ET, and an Irrigation Planner tool for scheduling water for...

Free | Regional

Oklahoma State University database of soil physical and hydraulic properties at Oklahoma Mesonet sites, supporting soil-water balance, soil moisture interpretation and...

Free | Oklahoma

University of Oklahoma / OWRB lake-level monitoring data portal providing measured reservoir and lake water-level time series for Oklahoma waterbodies.

Free | Oklahoma

Tree-ring reconstructed Palmer Drought Severity Index for Europe, North Africa and the Middle East, with a web application to generate maps and time series of instrumental and...

Free | Europe, North Africa, Middle East

Pacific Islands Ocean Observing System ERDDAP server delivering coastal water-quality, mooring, buoy and beach water-quality data for Hawaii and the U.S.

Free | Regional

Scripps Institution of Oceanography Spray underwater glider ERDDAP serving subsurface temperature, salinity and velocity profiles from sustained glider lines in the Pacific and...

Free | Global glider lines

The official global river network database underpinning SWOT satellite hydrology products: 213,485 reaches and 10.7 million nodes for rivers wider than 30 m, with width, slope...

Free | Global

Texas A&M AgriLife network of 100+ stations across eight Texas regions providing reference evapotranspiration, daily weather summaries, and irrigation watering recommendations for...

Free | Regional

ERDDAP serving the Joint Archive for Sea Level research-quality and fast-delivery tide-gauge water-level data: the largest global collection of quality-controlled hourly sea-level...

Free | Global tide gauges

Numerical Terradynamic Simulation Group home of the MODIS MOD16 global evapotranspiration / latent heat flux product (8-day, 500 m), a core satellite water-flux dataset for...

Free | Global

Utah Climate Center network of ~54 automated weather stations providing ASCE-standardized reference evapotranspiration (ETo/ETr) and soil moisture for irrigation decisions across...

Free | Utah

University of Wisconsin-Madison AgWeather portal providing reference and potential evapotranspiration estimates and weather data for agricultural water management across Wisconsin.

Free | Wisconsin

Wisconsin Geological and Natural History Survey groundwater-level monitoring network including a real-time groundwater network with 15-60 minute interval data and historic water...

Free | Sub-national

New Mexico State University ZiaMet agricultural weather network providing weather, reference evapotranspiration and crop-water-use information to support irrigation scheduling in...

Free | New Mexico

Water quality data from nearly 50,000 U.S. water systems identifying 324 contaminants including PFAS. Updated February 2025.

Free | 50,000 water systems

Satellite-based evapotranspiration at quarter-acre resolution across 48 contiguous U.S. states. Expanded from 23 states in December 2025. Over 13,000 users.

Free | 48 states

One of the largest citizen-science microplastic surveys ever conducted. 1,058 volunteer expeditions collected 2,677 water samples from every continent and ocean between 2013-2017.

Free | All continents and oceans, 2,677 water samples

Greenhouse gas fluxes (CO2, CH4, N2O), sediment organic matter, groundwater and surface water chemistry (DOC, dissolved oxygen, total dissolved nitrogen, nitrate, specific...

Free | Farmington River Watershed, CT/MA

CAMELSH: first large-sample hourly-scale hydrometeorological dataset for the contiguous US, integrating 11 NLDAS-2 meteorological variables, 634 catchment attributes (from...

Free | 9,008 catchments (CONUS)

Repeated sampling of distributed river water chemistry from the Kuparuk River, Oksrukuyik Creek and Trevor Creek watersheds, Alaska (Arctic LTER), including sampling date, season...

Free | North Slope, Alaska

Long-term physical and chemical limnology data for the North Temperate Lakes LTER site, Wisconsin, USA, including temperature, dissolved oxygen and nutrient measurements...

Free | North Temperate Lakes, Wisconsin

Continuous (15-minute) water quality monitoring time series for the Central Delta region of the Sacramento-San Joaquin Bay-Delta, California (2005-ongoing), published via the...

Free | Sacramento-San Joaquin Delta, California

LTER-affiliated ecological data repository hosting major freshwater datasets such as LakeBeD-US (500M+ lake water-quality observations), LAGOS and GLCP, with DOI-based access.

Free | USA / global ecology

Global 0.5-degree gridded aquifer properties dataset including recharge, lakes, depth to groundwater, aquifer thickness, WHYMAP classes, porosity and permeability, downloadable as...

Free | Global

Globally gridded aquifer properties (depth to groundwater, aquifer thickness, WHYMAP aquifer classes, porosity, permeability) at 0.5 degrees as CSV and shapefiles with R...

Free | Global

Globally gridded (0.5 deg) groundwater extractable volumes and unit costs from the superwell hydro-economic model across six depletion and ponded-depth scenarios, downloadable as...

Free | Global

Great Lakes Observing System's Seagull platform aggregates near-real-time and archived buoy and sensor observations across all five Great Lakes: water and air temperature, waves...

Free | Regional (Great Lakes, US/Canada binational)

Groundwater elevation measurements from four wells, evapotranspiration calculations, satellite NDVI vegetation indices, phenological dates and machine-learning training data for...

Free | Chalone Creek watershed, California

500+ million observations of lake water quality from 21 U.S. lakes across 17 variables. Provided in ecology and computer science formats for ML. Published 2025.

Free | 21 lakes

30 m resolution annual maps of irrigation distribution, frequency and change across the conterminous U.S.

Free | Conterminous United States

SWOT satellite mission data providing high-resolution measurements of water surface elevation for lakes, reservoirs, and rivers globally, launched December 2022.

Free | Global

Large-sample basin-scale hydrometeorological forcing data

Free | 671 basins in USGS HCDN-2009

US National Ecological Observatory Network open data: stream/lake surface-water chemistry, discharge, dissolved gases and rating curves across 80+ field sites.

Free | USA

Satellite-based field-scale evapotranspiration (ET) data for agricultural water management and irrigation scheduling across the contiguous United States.

Free | National

Vertical water profiles (temperature, dissolved oxygen, chlorophyll-a from YSI EXO2 sonde), discrete chlorophyll-a samples and species-level zooplankton counts from Portage Lake...

Free | Portage Lake, Minnesota

Greenhouse gas emissions data from US wastewater facilities

Free | US wastewater facilities

Stanford/Emory-led wastewater surveillance network covering 200+ U.S. treatment plants with public dashboards tracking SARS-CoV-2, influenza, RSV, norovirus, hMPV, and additional...

Free | 200+ U.S. utilities

Water quality (temperature, conductivity, dissolved oxygen, nitrate-N) and spatial coordinates from nine sampling runs along a 12.4-km reach of the Des Moines River in Central...

Free | Des Moines River, Iowa

Biological and Chemical Oceanography Data Management Office (Woods Hole) ERDDAP with ~2,500 datasets of marine biogeochemistry, nutrients, and water-column observations from...

Free | Global oceans

The original CAMELS dataset: daily hydrometeorological forcing (Daymet, NLDAS, Maurer), USGS streamflow, and catchment attributes (topography, climate, soil, geology, land cover...

Free | 671 catchments (CONUS)

Pacific Disaster Center's public multi-hazard risk and early-warning platform integrating global flood inundation information, severe-weather and disaster monitoring from...

Free | Global

EDI data repository hosting the LAGOS-US lake research platform (location, water quality, networks, and Landsat-derived estimates) for 479,950 US lakes/reservoirs, with...

Free | Conterminous United States

Hydrologic Research Center, developer of the WMO Flash Flood Guidance System providing operational flash-flood threat guidance products to 60+ countries using satellite/radar...

Limited | 60+ countries

Gulf of Mexico Coastal Ocean Observing System maintains multiple ERDDAP servers serving buoy and station water quality data (dissolved oxygen, salinity, temperature, chlorophyll...

Free | Regional (Gulf of Mexico)

Open-source project from Waterhackweek for mapping groundwater contaminants including arsenic and nitrate using Python, with Jupyter notebooks, data processing scripts, and...

Free | US groundwater contaminant mapping tools and datasets

Grassroots network integrating high-frequency buoy sensor data (temperature, dissolved oxygen, chlorophyll) from 80+ lakes across 51 countries for limnological synthesis.

Free | Global lakes

Gulf of Mexico Research Initiative Information & Data Cooperative ERDDAP server hosting thousands of oceanographic datasets including water chemistry, temperature and buoy data...

Free | Gulf of Mexico

Long-term experimental forest record measuring precipitation and streamwater chemistry at least weekly since 1963 across nine gauged watersheds in New Hampshire: ammonium...

Free | Local (Hubbard Brook, NH)

MIT Joint Program on the Science and Policy of Global Change produces datasets on water systems under climate change, including global water demand projections and water stress...

Free | Global

ERDDAP data server of the Northeastern Regional Association of Coastal Ocean Observing Systems with near-real-time and historical buoy observations across the Gulf of Maine...

Free | Regional

Historical wastewater treatment data 1996-2019

Free | 1M+ treatment records

Multi-hazard early warning, risk analytics and situational awareness platform providing near-real-time flood and drought hazard information across 28 hazard types globally, with a...

Limited | Global

Pacific Islands Ocean Observing System ERDDAP server distributing coastal water-quality datasets including Maui citizen-science coastal water quality, nearshore sensor and buoy...

Free | Regional

High-resolution spatial climate data for the United States

Free | USDA official climatological data

ERDDAP server of the Southeast Coastal Ocean Observing Regional Association serving downloadable time-series water-quality and oceanographic data from coastal and offshore...

Free | Regional

Stanford University's Water in the West program and Woods Institute for the Environment produce datasets and tools for western US water management, including groundwater...

Free | Regional

Comprehensive database of groundwater well records

Free | 13.5M+ well records

Alaska real-time sensor map and data explorer aggregating >7,000 live sensors from 2,500+ marine and terrestrial stations, served via Axiom's sensor API and ERDDAP-style services.

Free | Alaska

Combined CeNCOOS/SCCOOS California ocean data portal aggregating shore stations, buoys and models with download via ERDDAP and THREDDS in CSV and NetCDF.

Free | California coast

Regional ERDDAP serving real-time shore-station and buoy water-quality data (temperature, turbidity, dissolved oxygen, chlorophyll) for central and northern California.

Free | Central & Northern California

Chesapeake Bay Program data hub providing the CBP Water Quality Database (1984-present) across tidal, shallow-water and nontidal monitoring programs, with downloadable query...

Free | Chesapeake Bay watershed

Delaware River Basin Commission portal providing water resources data, water quality monitoring results, flow and reservoir information, and reports for the Delaware River Basin.

Free | Regional

DRBC water-quality data page offering downloadable datasets for DRBC monitoring projects (Delaware Estuary, chlorides, dissolved oxygen/nutrients, contaminants of emerging...

Free | Delaware River Basin

ERDDAP serving oceanographic and meteorological near-real-time and historical observations from the Gulf of Mexico in-situ observing systems.

Free | Gulf of Mexico

IOOS regional association aggregating Great Lakes observing data (water levels, temperature, currents, water quality, buoys) from federal, state and private partners via an open...

Free | Regional

Mid-Atlantic ocean data portal integrating underwater glider data, HF-radar surface currents and satellite SST, accessible via ERDDAP and THREDDS/OPeNDAP services.

Free | US Mid-Atlantic

ERDDAP data server of the Northeast Regional Association of Coastal Ocean Observing Systems serving real-time and historical buoy, mooring, tide gauge, currents, waves and water...

Free | Gulf of Maine / Northeast US

Southern California ERDDAP hosting weekly pier water-quality and harmful-algal-bloom monitoring (domoic acid, chlorophyll-a, nutrients, temperature) from the CalHABMAP program.

Free | Southern California

Southeast US coastal ocean observing portal with real-time and historical buoy, water-quality and model data; underlying data served via IOOS standard services including ERDDAP...

Free | Southeast USA

ERDDAP server of the Southeast Coastal Ocean Observing Regional Association with ~2,000 datasets covering buoys, gliders, HF radar, sea surface temperature and coastal water...

Free | US Southeast coast

Susquehanna River Basin real-time water quality

Free | Susquehanna River Basin

California Value Integrated Network for water resources

Research | California water system

R package for water data retrieval from USGS and EPA

Free | US water data sources

R package for statistics on daily values of water data

Free | Daily water data statistics

Python package for accessing and analyzing hydrological data

Free | US hydrological data analysis

National Oceanic and Atmospheric Administration data tools

Free | US atmospheric and oceanic data

Energy and water tracking tool by EPA

Free | US commercial buildings

R package with base functions for water resources

Free | US water resources analysis

Landscape water budgeting and irrigation efficiency

Free | Landscape irrigation systems

Water efficiency calculation tools by EPA

Free | US water conservation programs

Hydrocron is a NASA PO.DAAC API that repackages SWOT satellite L2 HR river reach/node and prior-lake shapefile products into CSV or GeoJSON time series, queryable by SWORD...

Free | Global

Cloud-based Sentinel-1 SAR flood monitoring service (NASA SERVIR / University of Alaska Fairbanks ASF) producing 30 m surface-water extent (HYDRO30) and flood-depth (FD30)...

Free | Global

NASA Goddard Earth Sciences page for the GSFC GRACE/GRACE-FO global mascon product: monthly time-variable gravity expressed as equivalent water height over 41,168 equal-area...

Free | Global

NASA Goddard portal providing satellite-altimetry-derived water level deviations and lake-extent products for operational lakes and reservoirs worldwide, at 10-day and monthly...

Free | Global

NASA ICESat-2 mission data-products page including ATL13 along-track inland water surface height for lakes, reservoirs, rivers and coastal waters from the ATLAS photon-counting...

Free | Global

NASA Land Information System framework and its land data assimilation instances (GLDAS, NLDAS, FLDAS, NCA-LDAS) fusing multi-sensor satellite observations to produce gridded soil...

Free | Global

GRanD v1: 6,862 reservoirs and associated dams (cumulative storage ~6,197 km3) with attributes, hosted on the NASA Open Data Portal (Socrata) with downloadable geospatial files.

Free | Global

Open documentation and worked tutorials for discovering and downloading NASA/CNES SWOT surface-water hydrology products (river vector, lake vector, raster, pixel cloud) from the...

Free | Global

Gridded riverine and coastal flood inundation depth maps for 9 return periods (2 to 1000 years) under baseline and future (2030/2050/2080) climate scenarios, produced by WRI...

Free | Global

Colorado Water Quality Monitoring Council network letting users select sampling locations on a map and download AWQMS, NWIS and STORET surface-water quality data for Colorado.

Free | Colorado

NGO marine water-quality monitoring programme (Clean Water for Reefs) collecting nutrient, turbidity and bacteria data at reef sites to address land-based pollution threats to...

Free | Global

The Nature Conservancy tool assessing health of 246,017 groundwater-dependent ecosystem polygons in California using Landsat NDVI/NDMI, PRISM precipitation and DWR groundwater...

Free | Subnational

The world's largest ocean trash dataset from the annual International Coastal Cleanup and Clean Swell app.

Free | 100+ countries, coastal and waterway locations

Documentation and access point for the OpenET API delivering satellite-based field-scale evapotranspiration and water-use data (monthly from 2000, daily from 2016) across the...

Free | North America

American Water Works Association utility benchmarking program providing 60+ key performance indicators for North American drinking water and wastewater utilities, plus annual...

Limited | United States & Canada

Centralized hub for volunteer and community-based water quality and benthic macroinvertebrate monitoring data throughout the Chesapeake Bay watershed, publicly queryable and...

Free | Regional (Chesapeake Bay watershed)

NGO-run public database holding 150,000+ certified water-quality data points for surface water and groundwater across ~3,000 sq mi of Central New York, including stream/lake...

Free | Regional

Environmental Working Group interactive map showing co-occurrence of arsenic, nitrate, and chromium-6 in drinking water affecting 100 million+ people in the US, with system-level...

Free | US drinking water systems: 100M+ people affected

Environmental Working Group interactive map showing locations of large and very large US community water systems that detected nitrate at or above 5 mg/L between 2017-2019, with...

Free | Large and very large US community water systems

Real-time water-quality monitoring dashboard for the Anacostia, Potomac and Shenandoah Rivers (DC region), with EXO2 sondes logging pH, temperature, conductivity, dissolved...

Free | Regional

Commercial and public-sector wastewater epidemiology platform with open dashboards for SARS-CoV-2 and opioid metabolites across U.S.

Free | National (sewershed-level)

Google's operational AI-driven riverine flood forecasting portal showing real-time river gauge forecasts up to 7 days ahead, covering river reaches across over 150 countries.

Free | 150+ countries

Live US river flow report joining 10,000+ USGS streamgauge readings to named river geometries, ranking rivers by discharge, percent-of-normal and length.

Free | 10000+ USGS streamgauges, USA

Statewide portal aggregating Oregon's water-related datasets, maps and tools covering groundwater, surface water, water quality, water quantity and infrastructure data.

Free | Sub-national