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Current Water Levels for Chester County
90-Day Precipitation Indicator Graph
Updated Daily
A useful metric for the amount and timing of precipitation is the 90-Day Precipitation Indicator Graph (shown above). The rainfall data is collected by the National Weather Service (NWS) and published by the U.S. Geological Survey and provide a reference for whether or not recent precipitation amounts are within normal levels, or if the region is entering a drought watch, warning, or emergency.
For 2022 and 2023, the graph illustrates that for most of the past year, Chester County had normal or above normal rainfall as indicated by the black line, which is the measured 90-day cumulative rainfall, being in or above the green band. There was a period in the winter and early spring of 2022 when the rainfall dropped below the historic average. When the black line in the graph above is in the green band, it means that rainfall over the past 90-days is considered "normal" from 25% above to 25% below the historic average. The yellow band indicates drought watch (from 25% to 35% below average), the orange is drought warning (from 35% to 45% below average), and the red is drought emergency (greater than 45% below average).
90-Day Precipitation Total and Departure from Average
Updated Daily
The National Weather Service's Middle Atlantic River Forecast Center publishes updates on total rainfall (in inches) as well as the surplus or deficit for each county across the state.
The illustration above is for the past 90 days. Counties shaded blue or green have a rainfall surplus and counties shaded yellow, orange, or red have a rainfall deficit.
30-Day Moving Average for Groundwater
Updated Daily
With precipitation surpluses in 2022, groundwater levels have generally remained in the "normal" range throughout 2022. While not reflected in the graph above for Well 10, groundwater levels in some areas of the County have dipped below the normal range in the summer and fall of 2022; monthly recorded water levels for other wells in the County is available on the CCWRA Observation Well Network web page.
One of the wells monitored by the U.S. Geological Survey is located in central Chester County (West Marlborough Township). The USGS plots the 30-day moving average of the water level compared to normal and drought indicators. When the black line is in the green band, groundwater levels at that location are "normal" or between 25% above and 25% below the historic average.
USGS Observation Well Network in Chester County
Updated Monthly
There are 22 observation wells measured by the USGS, with one well outfitted with a data logger to monitor the water level hourly and the other 21 wells measured once per month.
The well with hourly data is Well CH 10 (link to USGS web page)
Wells Measured Monthly around the 20th of each month
(Most Recent Published Information)
30-Day Moving Average for Stream Flow
Updated Daily
Stream flows are a combination of groundwater flowing to streams and runoff from rain events. In 2022, stream flows in Chester County were typically within the 'normal' range (the green band in the above graph). The graph shown above is for the Brandywine Creek at Chadds Ford which is one of the larger creeks in Chester County.
The U.S. Geological Survey plots the 30-day moving average of the water level compared to normal and drought indicators. Sharp increases in the black line are following significant storms that raise the water levels well above normal levels.
7-Day Average Stream Flow
Updated Daily
The U.S. Geological Survey provides a map of the status of stream flows across the state compared to historic stream flow levels. Locations that are green are at normal levels, locations in blue are above normal and locations that are orange or red are below normal.
Source: USGS WaterWatch web page