Resources for Quantitative Watershed Data


The EPA maintains a national database of water quality monitoring results known as the Storage and Retrieval Data Warehouse, or STORET. The data on this site are not monitored by the EPA, but instead provide a central location to deposit and download the watershed data collected by groups across the country. Data submitted to STORET, through the Water Quality Exchange (WQX) also maintained by the EPA, must meet certain quality and reporting criteria, assuring all data of documented quality. Data are then readily accessible by any all user groups. Data found include:

  • Chemical parameter measurements made in the field or lab
  • Physical parameter measurements such as water temperature or pH
  • Biological sampling results
  • Habitat assessments or observations

State Level Monitoring Data

While STORET is meant to serve as a national repository for monitoring data, depending on your state and their level of involvement in assembling data it may at times make more sense to utilize the a state level database. In Wisconsin, state level data can be accessed from the Wisconsin DNR. If accessing data in another state, it is a good idea to assess their maintenance of the resource before using it as a primary source. Because Wisconsin offers reliable and timely database management, an overview is provided below.

WI DNR: SWIMS Database

Wisconsin’s Surface Water Integrated Monitoring Systems, or SWIMS, provides a central repository for both agency-level Clean Water Act monitoring data and the data collected by the State’s extensive network of volunteer monitors. While access to the database itself requires registration, anyone wishing to explore Wisconsin’s waterways and water quality issues can easily do so through the user friendly Surface Water Viewer. This application enables users to explore the state’s waterways in a web-based mapping program that contains numerous layers including listed waters, monitoring stations, and permit holders. Additionally, users can locate monitoring stations and readily access their recorded data.

USGS – National Water Information System

The US Geologic Survey maintains its own monitoring sites, accessible online through the National Water Information System (NWIS). Data is available for a long list of parameters including flow, water quality (including both nitrogen and phosphorus), meteorological, physical, and ‘miscellaneous’, including algae, sampling info, et cetera. However, not all data is available for all sites, so it is important to check availability within your watershed sites before relying too heavily on these data.

In addition to this general database, USGS maintains several other resources that could be useful in targeting efforts, summarized below.

Name (Linked) Description Data Type
Water Quality Watch Real-time surface water data including temp, flow, pH, others Web-based, non-downloadable
National Stream Quality Accounting Network Reports and data on concentrations major rivers and loads in basins in the US Reports, Downloadable Data, Interactive Map
National Atlas – Water General water quality and hydrography data, mostly useful as support data for GIS-base analyses Web-based, GIS layer download
Annual Water Data Report Mapper Summary Reports of many of the NWIS sites, completed annually Reports accessible through interactive map


Water Quality Portal

The Water Quality Portal (WQP) allows users to simultaneously access both the USGS NWIS and EPA’s STOREIT. While it is potentially cumbersome, this resource can be useful in inventorying existing data availability for your site. Available from: