Persistent Organic Pollutants in the Squam Watershed

     In 2005, Squam loons experienced a dramatic decline followed by years of breeding failures. The Loon Preservation Committee (LPC) investigated the cause of this precipitous decline by testing non-viable eggs for contaminants. Many eggs exhibited high levels of both legacy (such as PCBs) and modern (flame retardants such as PBDEs) contaminants. Results from tributary sediment tests indicate high levels of DDT and PCBs in two Squam tributaries. The tests suggest DDT is from more recent application, even though the chemical was banned in 1972.

     The LPC’s discovery of toxic chemicals, such as PCBs and DDT, in sediment in Squam’s tributaries and loon eggs is concerning. Following these concerns, Yellow Perch and Smallmouth Bass were collected from Squam in 2018 in conjunction with NH Fish and Game and NH Department of Environmental Services (DES). The US Environmental Protection Agency analyzed samples for PCB concentrations, and DES issued a press release on March 30, 2020 (found here). Elevated levels of PCBs in fish has prompted more restrictive guidelines for human consumption in Squam Lake, described in the DES press release. This is a bioaccumulation issue, not a contact issue. These chemicals bind to sediments that settle to the lake bottom, and it is unlikely they pose any immediate threat to people swimming, boating or practicing catch-and-release fishing on Squam Lake. Our press release can be found here: SLA announcement of new fish consumption guidelines notice

What is next?

We will continue to work with DES and the LPC to follow up and study these results to do everything we can to make sure there is no long term threat to the lake, the people, and the wildlife that call this place home. We are actively leveraging the updated Watershed Management Plan to promote and restore shorelines and streams, reducing the input of Phosphorus and contaminants into the lake.

Where did the PCBs come from?

We are unsure. Experts suspect the PCBs may have been in oil historically sprayed on dirt roads to limit dust. Rain may have washed the oil-laden sediments into the lake, resulting in PCBs in lake sediments. Other ideas point to years of rain and snow contaminated from factories in the western US. The first fish consumption guidelines in NH were based on Mercury found in fish, which was a result of acid rain that became polluted from the same western factories. Statewide fish consumption guidelines can be found here

Is Squam different than other lakes?

Again, we are unsure. Squam is the only NH lake ever tested for PCBs! The goal of all partners is to do more testing in Squam and other lakes to determine the extent of the problem.

Contact SLA Director of Conservation Tyson Morrill with questions or for more information.