Overview

This application provides a snapshot of current groundwater levels across the United States relative to measured historic monthly levels. Data are obtained from the National Water Information System (NWIS) and National Groundwater Monitoring Network (NGWMN) . To the left of the map are a number of data filters allowing one to modify the data shown on the map by state, national aquifer, type of data (discrete measurements, continuous measurements, non-USGS NGWMN data), water level percentile categorization, sites in the Climate Response Network (CRN) , and also includes filters to view only sites with data collected within the past 30 days, and a filter to hide the sites with insufficient historical information (10+ years of measurements for the given month) to generate percentile ranks ('Not Ranked' sites). Below the map is a table with some information about the sites shown on the map, it dynamically adjusts as the filters on the left are altered. The background map layers and labels can be switched using the small layer icon in the bottom left corner of the map.

Data Sources

Current and historical groundwater data are fetched from the National Water Information System (NWIS) web service, and the National Ground-Water Monitoring Network (NGWMN) web service. Non-USGS NGWMN sites are assumed to be regularly monitoring groundwater levels, while only NWIS sites within the Active Groundwater Level Network (see 'aw' outputDataTypeCd), which includes sites with a water level measurement taken at least once within the past 13 months, are displayed in this application. Some exceptions apply. For example, sites part of an occasional data collection program, or sites for which there is pending funding for future measurements may be shown. Similarly, sites for which there was formerly funding for data collection may still be shown in the Active Groundwater Level Network.

Data Retrieval

NWIS data is gathered using the dataRetrieval R package. 'Discrete' water level measurements are collected using the dataRetrieval::readNWISgwl function, which queries the NWIS USGS Groundwater Levels Web Service , a service that provides historical manually-recorded groundwater levels. For this query, the USGS parameter code '72019' is used, which corresponds to 'Depth to water level, feet below land surface' per the Groundwater Levels Web Service Documentation. 'Continuous' water level measurements are obtained from NWIS using the dataRetrieval::readNWISdv function, which queries the USGS Daily Values Site Web Service. When collecting these data, the '72019' parameter code is also used. For these data, both the 00001 (maximum) and 00003 (mean) Statistics Codes are collected. These data are compared, and the statistic code with more data is used for the subsequent percentile calculations. This step is taken as different regions measure and record their water depth data differently, with some using the maximum statistic code, and others making use of the mean statistic code. In the event of a tie (both data records have the same number of entries), the mean values are used.

Computational Methods

National-scale NWIS site percentile values are computed daily using the precompute package. Statistics computations, tables, and plots are computed using the HASP package. Data is fetched from web services using the dataRetrieval package. For the non-USGS NGWMN sites, the precompute package is used to request a shapefile with the latest water-level percentile information from the NGWMN itself, per instructions in this tip sheet. As a consequence, the percentile values for non-USGS NGWMN sites are calculated by NGWMN, per their statistics methods documentation. Similar to the NGWMN criteria, the NWIS data at a site must have at least 10 years of data for the given month in order to be given a percentile rank. Sites with a historical record shorter than 10 years for a particular month are not ranked at this time.

Note: Data shown on the national map are refreshed daily, and may not reflect the most recently collected values. In contrast, the individual site pages (accessed via link in the site pop-up, or from the summary table below the map) do access and display the latest and most up-to-date information for a given site.

The source code behind this application is open-source and freely available in a GitLab code repository This application is made using the R Shiny library.

Regional Applications

A number of regional groundwater monitoring applications exist and are developed and maintained by local Water Science Centers. These applications may offer specific or additional information relevant to stakeholders and cooperators in that area. Please refer to the links below to be re-directed to your regional application:

Groundwater Levels in New England
Pennsylvania Groundwater Watch
Virginia and West Virginia Groundwater Levels and Trends
Groundwater Levels in Ohio, Kentucky, and Indiana

Disclaimer

This software is preliminary or provisional and is subject to revision. It is being provided to meet the need for timely best science. The software has not received final approval by the U.S. Geological Survey (USGS). The software is provided on the condition that neither the USGS nor the U.S. Government shall be held liable for any damages resulting from the authorized or unauthorized use of the software. This software is in the public domain because it contains materials that originally came from the U.S. Geological Survey, an agency of the United States Department of Interior. For more information, see the official USGS copyright policy. Although this software program has been used by the U.S. Geological Survey (USGS), no warranty, expressed or implied, is made by the USGS or the U.S. Government as to the accuracy and functioning of the program and related program material nor shall the fact of distribution constitute any such warranty, and no responsibility is assumed by the USGS in connection therewith. This software is provided 'AS IS.'

License

This software is a product of the U.S. Geological Survey (USGS), an agency of the United States Department of Interior, which is part of the U.S. Government. Users do not need a license or permission from the USGS to use this software. Users can download and install as many copies of the software as they need. See Exceptions below.

Cost

This software is freely distributed. There is no fee to download and (or) use this software.

Public domain

As a work of the United States Government, this USGS product is in the public domain within the United States. You can copy, modify, distribute, and perform the work, even for commercial purposes, all without asking permission. Additionally, USGS waives copyright and related rights in the work worldwide through CC0 1.0 Universal Public Domain Dedication.

Exceptions

This project may have numerous dependencies from other open-source software projects. The re-use and distribution of those software packages may be subject to the licenses of each of those dependencies.

Feedback

Please direct any feedback, questions, comments, or complaints about this application to: comptools@usgs.gov