As a regulatory requirement of Entergy’s Clean Water Act permit (NPDES permit), Entergy must publish monthly reports for pollutants discharged into Cape Cod Bay by its Pilgrim Nuclear plant. Entergy must collect samples and data, conduct some tests on the samples, and report the results to the U.S. Environmental Protection Agency (EPA). The monthly reports are called Discharge Monitoring Reports (DMRs).

Below are some highlights from Pilgrim’s latest DMR from September 2016.

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Pilgrim’s storm drains are supposed to be tested twice per year for pollutants, as required by EPA. Despite this, Entergy has failed to conduct the sampling over roughly the past 10 years, according to EPA.[1] Up until this September DMR, sampling had only occurred three times since January 2009, and only three of the four storm drains were tested (drain #004 has been omitted in the past, and continues to be according to this latest DMR).

There is also a fifth “miscellaneous” storm drain has never been covered under any permit, and therefore has never been tested.

While it is known that radioactive tritium has been leaking into the groundwater and soils on the site since at least 2007, whether this contamination has been discharged to Cape Cod Bay via these storm drains is unknown since testing for radionuclides is not required for the drains. Currently, the storm drains – when rare testing occurs – are only monitored for oil/grease and total suspended solids.

Even more concerning is that when storm drain sampling was done more frequently (from 1998-2007), parameters were exceeded on many occasions. Not only has testing rarely been done, but exceedances were likely regularly occurring and went unreported to state and federal regulatory agencies. No penalties for the lack of testing or for the known exceedances have ever been imposed.

Pilgrim has twenty-five electrical vaults on site that are a source of stormwater, and these vaults and other sources of untreated water are pumped out to the stormwater drains and directly into Cape Cod Bay. Sampling by EPA from only seven vaults found total suspended solids, cyanide, phenols, phthalates, PCBs, antimony, iron, copper, zinc, lead, nickel, cadmium, hexavalent chromium present. Lead, copper, and zinc exceeded marine water quality criteria.

Only in 2016, and after going unmonitored for years, EPA and MassDEP established new draft testing requirements for the twenty-five electrical vaults and stormwater drains. In the new testing requirements developed by EPA, not all of the pollutants listed above are included and only 5 of the 25 vaults have to be tested periodically. The new testing requirements have only been offered in draft form, and still have not been finalized and therefore do not currently apply.

As climate change impacts get worse and decommissioning commences in 2019 storm drains and stormwater testing will become even more critical, as these outlets could become further conduits for pollution into Cape Cod Bay as sea levels/groundwater rise and storms/flooding gets worse at the site.


Pilgrim’s September 2016 DMR states that chlorination of Pilgrim’s condenser cooling water occurred almost the entire month (23 of 30 days). This chlorinated water is discharged into Cape Cod Bay. Chlorination of cooling water is used as a form of bio-fouling to control bacterial and algal slime that builds up on the internal pipes, especially in the hot summer months.


When Pilgrim draws in sea water from Cape Cod Bay, it also draws in marine life. The process entrains small marine organisms (e.g., fish and shellfish eggs and larvae) through the system and impinges larger organisms on the intake screens (e.g., adult and young fish and shellfish). Tens of millions of fish and billions of planktonic organisms are killed every year through impingement and entrainment.

Entergy is required to report these “minor” or “brief” impingement events to U.S. EPA and MassDEP and list them in the monthly DMRs. As always, Entergy attributes these impingement events to “natural circumstances,” not to the once-through cooling system that pulled an average of 446 million gallons of water from Cape Cod Bay in the month of September (see below). Furthermore, there are no studies that have investigated the lasting, long-term impacts of these impingement events on the species or the ecosystem, but yet these large fish kills are quickly labeled as having “no effect.”

Furthermore, menhaden is considered one of the most important fish in the sea. It’s an important food source for many species, including commercially and recreationally important fish such as tuna, striped bass and cod. Menhaden are a critical part of the ocean food chain. However, due to overfishing there has been a 90% plunge in the menhaden population over the last 30 years. Although menhaden are not eaten by people, the fish are ground up and used in fertilizer and animal feed or used as fish-oil dietary supplements for people.

Despite concern about menhaden declines and the work being done to recover the population, Pilgrim takes large numbers of these fish every year – by impinging adults and young fish on the intake screens and entraining eggs and larvae through the system – without any regulations or penalties.


[1] EPA’s 2016 Draft Authorization to Discharge under the National Pollution Discharge Elimination System (Fact Sheet) Learn more →