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Maryland State Government Maryland Department of the Environment

Maryland Shellfish Harvesting Areas

bullet Daily Advisory on Conditionally Approved Shellfish Harvesting Areas

Maryland's Chesapeake Bay waters have long been known for their plentiful shellfish. To protect this valuable resource and safeguard public health the Maryland Department of the Environment is responsible for regulating shellfish harvesting waters.

Shellfish include clams, oysters, and mussels. The term shellfish does not include crabs, lobsters, or shrimp. Shellfish are filter-feeding animals: they strain the surrounding water through their gills which trap and transfer food particles to their digestive tract. If the water is contaminated with disease-causing bacteria, the bacteria are also trapped and consumed as food. If shellfish are harvested from waters which the Department has restricted (closed) and eaten raw or partially cooked, they have the potential to make people sick. Therefore, it is mandatory for oysters and clams to be harvested from approved (open) shellfish waters only.

Shellfish harvesting waters which are open or approved for harvesting are those where harvesting is permitted anytime. Areas which are conditionally approved mean that shellfish harvesting is permitted except for the three days following a rain event of greater than one inch in a twenty-four hour period. Runoff from such a rainfall can carry bacteria into surface waters from adjacent land. Information about which areas have conditional closures is updated daily on the web and via a recording. Click here to find out which conditional closures are in effect or call 1-800-541-1210.

Maryland's Shellfish Harvesting and Closure Area Maps

These maps summarize the Maryland Department of the Environment’s (MDE) classification status of oyster & clam harvesting waters as of June 1, 2011.  The maps depict the classification of shellfish growing waters of the State as restricted, conditionally approved, seasonally conditionally approved or approved. 

Also shown in the maps are Shellfish areas closed as reserves and sanctuaries by the Department of Natural Resources (DNR).  Sanctuaries are areas which are closed to shellfish harvest and often contain oyster restoration projects to help enhance oyster populations for their environmental benefits.  These areas are permanent closures.  Reserves are areas which are restored, then opened for periodic harvest when certain criteria are met.

Mapping Information

    Interactive or "Clickable" Map of Maryland Shellfish Harvesting and Closure Areas

    MDE Executive Summary

    DNR Executive Summary

    Detailed Descriptions MDE's Shellfish Harvesting Areas

    Detailed Coordinate Information for DNR Closures

For more information concerning shellfish harvesting contact the MDE Shellfish Certification Division at (410) 537-3608 or the Natural Resources Police at (410) 260-8880. For interstate shellfish sanitation information, visit

Shellfish Fact Sheets

    Clean Water - Safe Shellfish

    Shellfish Safety Guidelines for Boaters and Commercial Harvesters

    Application Procedures for the Relaying of Shellstock from Polluted Waters for the Purpose of Natural Cleansing

Related MDE Press Releases

    Harvesting in Choptank River Temporarily Restricted (2/5/2009

Related Topics

    Agency Warns Against Eating Shellfish From Private Piers

    Detailed Explanation of Shellfish Area Conditional Closures

    Consumption Guidelines for Recreationally Caught Fish Species in Maryland

    Growing Oysters for Commercial Sale in Floats off of Private Piers

    Maryland Near Shore Report 2006

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