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Map

Interactive map showing the percentile of the most recently measured groundwater levels relative to long-term monthly statistics. Hovering over and clicking on each data point will provide additional information and data for the site. [NGWMN, National Groundwater Monitoring Network; NHGS, New Hampshire Geological Survey; <, less than; >, greater than; ≥, greater than or equal to; Not ranked, site has less than 10 years of data for the most recent month]

About this application

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This web page displays the latest water-level information for U.S. Geological Survey (USGS) wells monitored in and near New England. The application contains data from wells with continuous data (from sites with real-time data) and with periodic (monthly) measurements. Data from additional wells in New York are included for sites within about 25 miles of the border of the New England states. Data are also included from the National Groundwater Monitoring Network (NGWMN) in New Hampshire.

Well Types:

Continuous: Sites that currently have equipment to measure groundwater levels in real time. Measurement frequency is typically hourly, but can be as frequent as every five minutes. For these sites, the mean daily value for a given day is used in the statistics presented on this web page. Many of these sites began as sites with periodic water-level data collection.

Periodic: Sites that are measured using a calibrated water-level tape by personnel in the field. Measurement frequency for sites in New England is typically monthly.

Climate Response Network

The Climate Response Network includes wells that reflect climatic variability and not human influences. The climate variations of interest are those that affect recharge on monthly and longer time scales; not barometric or tidal influences. Observation wells in this network are required to satisfy the following criteria:

  • Open to a single, known hydrogeologic unit
  • Known well construction that allows good water-level measurements
  • Located in unconfined aquifers or near-surface confined aquifers that respond to climatic fluctuations
  • Minimally affected by pumpage and likely to remain so
  • Essentially unaffected by irrigation, canals, and other potential sources of artificial recharge
  • Long-term accessibility
  • Well has never gone dry (not susceptible to going dry).

National Groundwater Monitoring Network

Water levels from wells in New Hampshire with data collected by the New Hampshire Geological Survey. Data from these wells are shown in the USGS National Groundwater Monitoring Network (NGWMN). Data for these sites may either be periodic (monthly) or continuous (daily).

Statistics

Water-level measurements are presented within a statistical framework. The percentile provides this statistical framework. A percentile is a value on a scale of 100 that indicates the percentage of a distribution that is equal to or below that value. For example, on the map of groundwater levels, the water level at the 90th percentile is equal to or greater than 90 percent of the monthly median groundwater levels in a given month over the period of record at the well. In general:

  • a percentile greater than 90 is considered much above normal,
  • a percentile greater than 75 and less than 90 is considered above normal,
  • a percentile between 25 and 75 is considered normal,
  • a percentile between 10 and 25 is considered below normal, and
  • a percentile less than 10 is considered much below normal.

Functions in the R HASP package are used to calculate the statistics and create the graphs on the individual site pages. Many of the sites displayed in this application that now have continuous water-level data were originally sites with monthly periodic data. For this analysis, the data from the periodic and continuous periods (daily mean water levels) for these sites were combined into one record. This allows for the use of long-term monthly data in the calculation of monthly statistics. The percentiles are determined for each site for each month by taking the median value for the month in any year with multiple values in the month, then determining monthly percentiles. For USGS sites, percentiles are determined only using approved data. Recent data shown on the graphs may be provisional and subject to review. Monthly percentiles may change as new data are reviewed and approved. Sites with less than 10 years of data for the current month, are shown on the map as “Not ranked.” Data for these sites is graphed on the individual site pages, but should be used with caution as there may not be sufficient data for determination of water-level status.

The percentiles for sites in New Hampshire from data in the NGWMN are determined in the same way as for USGS sites; however, all data are assumed to be approved and used in the determination of statistics.

How to Use This Application

For navigating the map:

  • To move around in the map: use the arrow keys or shift + arrow key to pan around the map, or grab and drag with a mouse click.

  • To zoom in and out of the map: use the +/- buttons in the upper left to change the zoom level. This can also be done by rolling the mouse wheel. Clicking on the square button below the +/- buttons returns the map to the original extent.

On the included map, hovering your mouse cursor over a point will show the station name, and clicking on a point will show a pop-up window with site information, and the most recent water-level value, and the most recent percentile. Within a pop-up window, clicking on the blue highlighted text called “See site graph and statistics” will lead to a site-specific web page which displays a graph of the water levels at the site over the last year, relative to monthly water-level percentiles. A table shows the percentiles for each month and the statistics for the month with the most recent water-level values are highlighted in blue.

References

Cunningham, W.L., Geiger, L.H., Karavitis, G.A., 2007, U.S. Geological Survey Climate Response Network: Factsheet 2007-3003, 4 p. online at https://pubs.usgs.gov/fs/2007/3003/pdf/2007-3003-hires.pdf accessed June 30, 2022.

U.S. Geological Survey, 2022, National Groundwater Monitoring Network (web application), online at https://cida.usgs.gov/ngwmn, accessed on June 30, 2022.

DeCicco, L.A., Prinos, S.T., Eslick-Huff, P.J., Hopkins, C.B., 2022, HASP: Hydrologic AnalySis Package, v1.0.0., https://code.usgs.gov/water/stats/hasp, https://github.com/USGS-R/HASP, accessed on August 9, 2022.

Disclaimers

Data include approved, quality-assured data that may be published, and more recent provisional data, whose accuracy has not been verified. The data are being provided to meet the need for timely best science, and are 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 data. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government.

Last updated: March 27, 2025 Return to U.S. Geological Survey New England Water Science Center