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New Hampshire Department of Environmental Services

Media Center

DATE: March 30, 2020
CONTACT: Jim Martin, (603) 271-3710

NHDES Issues New Fish Consumption Advisory for Squam Lake
High Levels of Polychlorinated Biphenyls (PCBs) Detected in Fish Tissue

Concord, NH – The New Hampshire Department of Environmental Services (NHDES) today announced new, more restrictive fish consumption limits, for all fish caught in Squam Lake, as a result of high levels of polychlorinated biphenyls (PCBs) detected in fish tissue samples. In this study, NHDES followed up on previous research conducted by the Loon Preservation Committee and the Squam Lake Association that identified the elevated contaminant levels in loon eggs and lake sediment.

NHDES biology staff collected smallmouth bass and yellow perch samples in an effort to better understand the potential risks to human health associated with eating fish caught in the lake. The samples were analyzed for PCBs, Per- and Polyfluoroakyl Substances (PFAS), and mercury concentrations; only PCB data is available at this time.

NHDES collected 55 fish for chemical analysis by an EPA contract lab. Five smallmouth bass and seven yellow perch composite samples consisting of 4-5 individuals per sample were submitted for analysis. The findings were as follows:

  • PCB concentrations were higher in smallmouth bass than yellow perch.
  • PCB concentrations in smallmouth bass ranged from 3.99 to 22.81 parts-per-billion or ppb (average of 13.34 ppb).
  • PCB concentrations in yellow perch ranged from 3.44 to 7.49 ppb (average of 4.55 ppb).

NHDES evaluated the range of PCB concentrations in fish tissue for potential human health risks, specifically the cancer risk. Based on this evaluation, NHDES has concluded that the PCB concentrations in fish are high enough to present risks from exposure and their consumption should be limited.

Table 1. New Recommended Consumption Limits Based on Total PCB concentration.
  Adults and children >7 years of age (8 oz. meal) Women of childbearing age(8 oz. meal) Children <7 years of age
(4 oz. meal)
Smallmouth bass and other fish 1 meal every 4 months
(3 meals per year)
1 meal every 6 months
(2 meals per year)
1 meal every year
Yellow perch 1 meal every month
(12 meals per year)
1 meal every 2 months
(6 meals per year)
1 meal every 3 months
(4 meals per year)

The existing mercury-based statewide guideline of fish consumption for smallmouth bass and yellow perch is 1 meal per month for young persons and pregnant woman and 4 meals per month for adults and children 7 years old or older. In addition, the mercury guidelines state that only fish less than 12" in size should be eaten, which may be below the legal length limit for some species. NHDES encourage all anglers to adhere to the mercury fish consumption guidelines where ever they fish.

In comparison to the statewide mercury consumption guidelines, the recommended guidelines for fish consumption in Squam Lake are more restrictive. Further, the consumption guideline for smallmouth bass also extend to lake trout, salmon, hornpout and other fish species other than perch caught in Squam Lake.

However, it is important to note is that there is no known risk to catching and handling of fish in Squam Lake, so catch and release fishing is not impacted.

Background on PCBs:

Polychlorinated biphenyls are man-made chemicals used as coolants and lubricants in electrical equipment because they don't burn easily and are good insulators. The manufacture of PCBs was stopped in the U.S. in 1977 because of evidence that they build up in the environment, can cause harmful health effects, and are considered a probable human carcinogen.

For more information related to the new fish consumption advisory for Squam Lake, please contact David Neils, Chief Aquatic Biologist at NHDES, at or (603) 271-8865.


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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