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New Hampshire Department of Environmental Services

NH Department of Environmental Services and the NH Fish and Game Department Announce New Shellfish Harvest Closures for 2015

Due to recent findings from a dye study in the Piscataqua River conducted by the US Food and Drug Administration (FDA) and the NH Department of Environmental Services (NHDES), the NH Fish and Game Department and NHDES announce a change to the schedule for allowable recreational shellfish harvesting in Little Bay and the Bellamy River. Effective January 1, 2015, recreational shellfish harvesting may only occur on Saturdays from 9:00am until sunset during the open season*, provided that temporary harvesting closures related to rainfall, wastewater treatment facility performance, red tide, or other unforeseeable circumstances are not already in place. The Saturday (9am-sunset) harvesting restriction only applies to harvesting in Little Bay and the Bellamy River. It does not apply to oyster or mussel harvest in Great Bay. Oyster and mussel harvest in Great Bay is allowable any day of the week during the open seasons* for these species, provided that temporary harvesting closures relating to rainfall, wastewater treatment facility performance, red tide, or other unforeseeable circumstances are not in place. Softshell clamming remains Saturday-only (1/2 hour before sunrise to sunset) for all other harvest areas in coastal New Hampshire. In addition to changes described for Little Bay and the Bellamy River, the harvest of all shellfish from Little Harbor and coastal shorelines around the mouth of Little Harbor will be prohibited until further notice.

In December 2012, the NHDES, with assistance from the FDA and other state/federal agencies, conducted a hydrographic dye study of Portsmouth’s Peirce Island municipal wastewater treatment facility. The study simulated a disinfection failure at the facility by injecting a red dye into wastewater effluent entering the Piscataqua River. Boats and monitoring equipment then tracked the dye transport, dilution, and dispersion as tidal currents moved the dye into shellfish harvest areas such as Little Bay, Great Bay, the Bellamy River, the Oyster River, Little Harbor/Back Channel, Portsmouth Harbor, and the Atlantic Ocean. The information from the study identified areas that were influenced by Peirce Island wastewater and illustrated that changes to when and where NHDES can allow shellfish harvesting are needed. The study and analyses were conducted in accordance with recently-approved guidelines in the National Shellfish Sanitation Program.

*for information about open seasons for various shellfish species, go to

map of coastal new hampshire shellfish harvest areas

Although wastewater facility disinfection failures are rare, they do occur. The December 2012 study showed that a release of undisinfected effluent from the Portsmouth facility can reach Dover Point/Little Bay in just over 4.5 hours, and the Bellamy River shortly after that. The speed of transport is so fast that harvesting in these areas must be tightly controlled to prevent harvesters from taking shellfish that has been exposed to accidental discharges of undisinfected wastewater. The typical management action for this type of situation is to close the areas to all recreational harvesting; however, F&G and NHDES are recommending an alternative approach to allow recreational harvesters to continue to have access to these areas. During the open seasons for the various shellfish species, harvesting will be allowed on Saturdays from 9:00am to sunset. The 9:00 am delayed harvest start time will allow NHDES and F&G to determine if any treatment failures occurred overnight. If a problem is found, the Clam Flat hotline (1-800-43-CLAMS) and the NH Coastal Atlas will be updated to communicate the harvesting closure.

map of 2015 new hampshire shellfish harvest open/closed zones

The 2012 study found that undisinfected wastewater effluent can also affect Great Bay, though not as quickly as Little Bay and the Bellamy River. Therefore, Great Bay harvesting need not be similarly restricted.

Shellfish aquaculture operations in Little Bay will continue working under current practices in which they must seek approval for each harvesting event. Because NHDES is in direct contact with each aquaculturist, harvesting can occur any day of the week.

Additional harvest closures will be implemented in Little Harbor and along the Atlantic Coast from Jaffrey Point (New Castle) to Odiorne Point. These precautionary closures are necessary because the study found levels of viral indicators in treated Peirce Island effluent to be much higher than levels discharged from secondary treatment facilities in coastal New Hampshire, such as facilities in Durham and Dover. The standards that NHDES uses to evaluate public health risks around wastewater outfalls, particularly the standards used to examine exposure to viruses, are applicable to secondary treatment facilities; thus they cannot be used to properly evaluate the risks to areas near the Peirce Island outfall. NHDES cannot certify that these areas are appropriate for harvest, so a precautionary closure is being put in place for areas such as Little Harbor and the Atlantic Coast around Little Harbor.

map of 2015 little harbor shellfish harvest open/closed zones

The City of Portsmouth is presently in the design phase of an upgrade of the existing wastewater treatment facility at Peirce Island to secondary treatment. NHDES anticipates that some of the public health risks and issues identified in the 2012 study may be alleviated when the new wastewater facility is operational. When the upgrade is complete, NHDES will reassess the public health risks and modify harvesting classifications accordingly.

NH Department of Environmental Services | 29 Hazen Drive | PO Box 95 | Concord, NH 03302-0095
(603) 271-3503 | TDD Access: Relay NH 1-800-735-2964 | Hours: M-F, 8am-4pm

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