Methodology for Beach Locations

The EPA gathers beach locations from state and local officials and provides those data in a central database.

The location data are provided in latitude and longitude format. For example, Long Beach, California is located at 33.757,-118.147. Learn more about latitude and longitude values.

The local or state officials in most cases have provided to the EPA with a "start" latitude/longitude and "end" latitude/longitude for each beach. There is a wide variety in the monitoring protocols for the different beaches, and we are unable to provide any information at present about the location of the monitoring locations. As a consequence, the icons are simply based on the mid-point of the latitudes/longitudes provided.

In some cases, the EPA database contained only a single point for the beach (not start and end points). In those situations we simply represented the beach as a single icon with no boundaries denoted.

When the EPA databases did not include a beach location, we requested additional information from state beach contacts and did a beach-by-beach inquiry using internet searches to attempt to find the beach location. Specifically, we ran several searches for missing beaches both using EPA's BEACON website and using Google searches for the beaches' attributes (name, beach ID, e.g.) to try to find location information.

Despite this effort, out of the 7200+ beaches we analyzed, we were unable to find latitude and longitude coordinates for roughly 4%. These beaches are listed in a pop-up underneath each state map.

Data Checking

We compared the map generated from EPA's data to several state and local government maps of beaches we found online to see if there was general agreement between our map and these other sources of information. We found that there was good overall agreement between our map based on EPA data and these other sources, and also identified additional beaches to investigate in more detail as we continue to improve the map.

We know there are remaining issues with the map:

  • Beaches without coordinates: As mentioned above, we continue to look for updated information on beach locations.
  • Disagreement between Satellite and Google Maps: Some beaches appear incorrect when viewed with Google Maps' regular view, but appear correct when viewed with the satellite view. In these situations, we relied on the satellite imagery instead of the Google Maps.

We Are Committed to Improving the Map

We welcome suggestions that will help us implement improvements to the beach location information. If you notice a problem with a beach, simply click on its icon, then click the "Let us know" link at the bottom of the window. When you submit a report, we are notified about the beach and your feedback. We'll review all submissions we receive, and will work with state coordinators to make needed corrections.

Furthermore, as EPA or state officials provide us with improved information about the beach locations, we plan to evolve the beach location information.


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