Flood Protection

The Chester County Water Resources Authority was created to provide sound water science, information and planning resources to support safe, healthy and prosperous communities throughout Chester County, PA. This includes real time water level monitoring through a partnership with USGS and guidance on floodplain management. The Authority also provides flood protection in the Brandywine Creek watershed through the operation of 4 flood control facilities and emergency response information.

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Local Flooding Information


There are 17 USGS water level gaging stations throughout Chester County. The real time water level of local creeks is continually monitored and the information is available for anyone to view. You can also sign up for Real Time Notifications to find out when there are rising waters in flood prone areas. Visit this page for more information.

FEMA and Floodplains in Chester County


The Federal Emergency Management Agency recently updated the floodplain maps for portions of Chester County. The new maps went into effect on September 29, 2017. To view the new interactive online FEMA floodplain maps, visit their Map Service Center website and type in the street address for the property of interest. Call FEMA Map Specialists at 1-877-FEMA-MAP. Also click here for other online resources we gathered to help you better understand the FEMA floodplains. Call Dani-Ella Betz from Chester County Water Resources Authority at 610-344-5400 or dbetz@chesco.org with any questions.

For more information and to find municipal resources, click here.


Regional Flood Control Program - Brandywine Creek Watershed


The Chester County Water Resources Authority owns and operates four regional flood control facilities and the Chambers Lake Reservoir (see map).

NRCS Dams Rehabilitation Program


Two separate, but concurrent, rehabilitation projects are underway on Beaver Creek Dam and Hibernia Dam. The projects are being conducted by the U.S. Department of Agriculture, Natural Resources Conservation Service, which was the federal sponsor of both dams when they were constructed.

For additional information regarding the planning study, please review the materials posted on these web pages:

Quick Facts of CCWRA's Dams


  • Robert G. Struble, Sr. Dam and Regional Flood Control Facility
    • Location - East Branch Brandywine Creek, Honey Brook Township
    • Year Completed - 1970
    • Total Flood Storage Capacity - 191 million gallons
  • Beaver Creek Regional Flood Control Facility
    • Location - Beaver Creek (East Branch Brandywine Creek watershed),
      West Brandywine and East Brandywine Townships
    • Year Completed - 1974
    • Total Flood Storage Capacity - 170 million gallons
  • Barneston Regional Flood Control Facility
    • Location - East Branch Brandywine Creek, Wallace Township
    • Year Completed - 1983
    • Total Flood Storage Capacity - 511 million gallons
  • Hibernia Regional Flood Control Facility
    • Location - Birch Run (West Branch Brandywine Creek watershed), West Caln Township
    • Year Completed - 1994
    • Total Flood Storage Capacity - 257 million gallons
  • Chambers Lake Reservoir
    • Location - Birch Run (West Branch Brandywine Creek watershed), West Caln Township
    • Year Completed - 1994
    • Total Water Supply Storage Capacity - 344 million galllons.
These four facilities were designed to work as a combined system to reduce flooding in the Brandywine Creek watershed. The four facilities provide flood reduction for all or portions of over 4,100 properties with an estimated cumulative assessed property value of approximately $427 million. The Authority implements a rigorous management and maintenance program to maintain the structural and operating integrity of the structures consistent with their design standards. In addition, the Authority owns and manages over 200 acres of riparian lands and easements as well as wetlands and two lakes associated with its flood control and reservoir facilities. Great care is taken to manage these resources in a manner that protects their environmental integrity and supports their natural resources while providing for public safety.


Managed Public Use Lands at our Facilities


Emergency Action Plans


An Emergency Action Plan has been developed for each of the four dams listed above. A copy of the plans, including the inundation maps noting areas subject to flooding in the event of failure, are available for public inspection at the office of the Chester County Water Resources Authority and the offices of the municipalites which are part of the inundation zone.

Additional information about these plans, as well as a list of municipalities which are part of the inundation zone can be found on CCWRA's Emergency Action Plans web page.

Watershed-Based Flood Protection


The Authority's flood control projects were planned, designed and constructed by the U.S. Department of Agriculture Natural Resources Conservation Service under PL 566 and the USDA National Watershed Protection and Flood Prevention Program. Click here for information on the watershed-based flood control programs, how a watershed dam works, and how flood control dams serve downstream development.

Winter Hydrology: Snowfall & Snowmelt


Throughout the winter, much of our attention is directed to weather forecasts to determine if snow is on the horizon, or how much snow fell in the past storm. Just as snowfall is a major source of water during the winter months, the snow on the ground (called the ‘snow cover’ or ‘snowpack’) is a significant storage of water during the winter months. When the snow cover melts much of the water flows over the land to streams, however there is some ground water recharge during the snowmelt as well. Even with the ground frozen, there are spaces where water can fill and flow down to the water table. This ground water recharge is critical to replenishing the aquifers for the upcoming spring and summer seasons.
 
There are a number of different ways to measure snowfall. One simple way is to use a snowboard and a ruler. A snowboard is simply a flat board that is placed on the ground. After the snowfall has accumulated, the depth is measured and recorded. Each time a measurement is taken, the snowboard is moved to the top of the snow. The rate of snowfall can be determined by taking measurements every hour or every six hours for example.
 
Another measurement of snowfall is to collect the snow and ice in a common cylindrical raingage, without the center measuring tube or top funnel. After the snow and ice are collected, the gage is placed in a warm area and melted. Then the melted precipitation is poured into the measuring tube and recorded. The result is the precipitation (as total water) in inches from the snowfall, which is the method that the CCWRA Volunteer Rainfall observers use.
 
The rule-of-thumb is that about 0.1 inches of precipitation (or water) results from every 1 inch of snow. A heavy, wet snow may be closer to 0.2 or 0.3 inches of precipitation to an inch of snow while a light, powdery snow may be less than 0.1 inch.

What Makes a Winter Storm?


Cold air:


Below-freezing temperatures in the clouds and near the ground are necessary to make snow and/or ice.
 

Moisture:


To form clouds and precipitation. Air blowing across a body of water, such as a large lake or the ocean, is an excellent source of moisture.
 

Lift:


Something to raise the moist air to form the clouds and cause precipitation. An example of lift is warm air colliding with cold air and being forced to rise over the cold dome. The boundary between the warm and cold air masses is called a front. Another example of lift is air flowing up a mountain side.
 
For more information, check out the National Weather Service Winter Storm Safety web page.
  

How a Typical Nor’easter Forms


The classic winter storm in the Mid-Atlantic region is called a Nor'easter. A low pressure area off the Carolina coast strengthens and moves north. Wind-driven waves batter the coast from Virginia to Maine, causing flooding and severe beach erosion. The storm taps the Atlantic's moisture-supply and dumps heavy snow over a densely populated region. The snow and wind may combine into blizzard conditions and form deep drifts paralyzing the region. Ice storms are also a problem. Mountains, such as the Appalachians, act as a barrier to cold air trapping it in the valleys and adjacent low elevations. Warm air and moisture moves over the cold, trapped air. Rain falls from the warm layer onto a cold surface below becoming ice.