Legal Terrain

Wastewater Treatment for Nutrients and the Continuing Saga of Unintended Consequences

June 6, 2024


We have written extensively on the recent rollout by EPA and the implications of PFAS requirements for monitoring and treatment by publicly owned water and wastewater (“WWTP”) treatment plants, including those operated as public-private partnerships. At the same time, the treatment of and removal of nutrients from wastewater – requirements added over the past 20 years – continue to raise challenges in the operation of treatment facilities while failing to skirt the Law of Unintended Consequences. A year ago, in my Legal Terrain article, “Today’s Challenges to Wastewater Treatment and Sludge Management,” I highlighted the daunting challenges of nutrient treatment and emerging PFAS treatment in creating unexpected consequences. After decades of nutrient treatment, those unintended consequences have emerged.

A recent article by Nancy Lavin, published in the Rhode Island Current titled “Under Pressure from AG, Woonsocket Officials Look to Cut Ties with Liquid Waste Customers,” reports that a historic industrial city, with slightly more than 40,000 residents, has determined to phase out acceptance of liquid sludge waste by a privately operated incinerator tied into its wastewater treatment facility. The wastewater solids incinerator, originally established some forty years ago in partnership with a local private concern, has grown over the ensuing decades to serve solids generated in major WWTPs in Rhode Island and urban areas of southern New England, serving hundreds of thousands of residents and businesses. Alternatives for nutrient-rich sludge disposal, such as agricultural land application, are shrinking due to PFAS concerns about the food supply. Meanwhile, growing concerns over accumulated phosphorus retained and accumulated in the wastewater treatment/sludge incineration cycle have led to acute challenges in WWTP operations and dramatically increasing costs.

Coincidentally, the Rhode Island shellfish industry has experienced a dramatic reduction in quahog (clam) harvesting in Narragansett Bay, potentially or at least in part due to the efforts to reduce the level of nutrients in wastewater discharged from WWTPs. Following the 1938 Hurricane, silt materials washed into the Bay, effectively eliminating the historic oyster beds and harvest. For decades prior, the Bay had produced substantial oyster harvests from bottomlands leased by the state to oyster fishing operations. Quahogs, which are mobile in soil unlike oysters, established themselves in the nutrient-rich waters and bottom soil of the Bay. During the 1950s and well into the 1980s, quahogs, some transplanted under state-funded programs from heavily polluted areas of the Bay and harvested by dredging, led to all-time peak harvests and employed 1000s of workers on the Bay. At one time, half and more of the clams in Campbells Clam Chowder reportedly came from Narragansett Bay.

Over recent decades, the harvest of quahogs from the Bay has fallen dramatically, even while more areas in and along Narragansett Bay are open to quahoging longer periods of the year due to the mitigating effects of enhanced wastewater treatment on water quality in the Bay. Currently, there is debate among shell fishermen, state environmental regulators, resource managers and academic experts about the cause of the substantial reduction of quahog landings and the amount of “meat” in each quahog. Dredging, which accounted for efficient harvesting, is no longer permitted in Rhode Island waters. Quahoging is now occupied by solo practitioners, often part-timers supplementing their income, and is subject to strict limits on bushels harvested at one time. State funding for transplants from restricted areas of the Bay has effectively ceased.

Some in the quahog business point to the dramatic reduction of nutrients in the waters of the Bay resulting from strict low limits on nitrogen in treated wastewater discharged from WWTPs along the Bay and rivers discharging into the Bay. Nitrogen and the phytoplankton it fertilizes in the Bay form the basic food sources for growing quahogs. Quahogers are now urging higher nitrogen winter and even summer limits for nitrogen in treated wastewater to support quahog growth.

Undoubtedly, numerous other factors may contribute to the decline of quahog harvesting in Narragansett Bay. Climate change, which has increased water surface temperature in Narragansett Bay by as much as 3°F, has reduced phytoplankton growth in the water column to feed quahogs while also increasing the population of crabs, which feed on young quahogs. Increased CO2 in the atmosphere and in Bay waters leads to hypoxic conditions in quahogs in the lower levels of the Bay bottom as temperature increases, which reduces available oxygen in those waters. This also contributes to acidity leading to depressed growth and shell damage.

As I urged last June, the challenges facing municipal and regional wastewater treatment plants, sludge incinerators, farm communities, and now quahogers and consumers, resulting from enhanced water pollution control regulations, require thorough consideration by all of us, and particularly regulators and public officials. Clearly, protecting our rivers and coastal waters from contamination is critical. However, regulatory requirements developed to reduce the impacts of nutrients need consideration during the rule-making process and periodic reconsideration based on unanticipated impacts to avoid or at least mitigate these unintended consequences.

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