By FRANK CARINI for ecoRI News (ecori.org)
The Narragansett Bay Estuary Program has developed a draft report on the status of Narragansett Bay entitled “State of the Bay and its Watershed.” The report assesses 24 indicators throughout the bay and its watershed — some 60 percent of it is in Massachusetts — based on best available science and current research efforts.
Public comments on the draft report will be accepted until the close of business May 22. Comments should be e-mailed to firstname.lastname@example.org. The Narragansett Bay Estuary Program (NBEP) will revise and finalize the report and prepare a summary based on public feedback.
ecoRI News recently went through the report. Numerous factors, beyond climate change, sea-level rise and legacy contaminants, stress Rhode Island’s most significant natural resource. Here is a look at some of the others detailed in the NBEP’s draft report:
The estimated populations in 2014 of the Massachusetts and Rhode Island sections of the Narragansett Bay watershed. (U.S. Census Bureau Block Projections)
Population growth typically leads to increased nutrient loading, more impervious surfaces and habitat fragmentation. From 2000 to 2010, the population living within the Narragansett Bay watershed increased by nearly 8 percent, to 1.95 million people.
Quote: “It is well established that the way human society uses and protects the land within a watershed has critical implications for freshwater streams, estuarine waters, and associated habitats.”
Quote: “To protect the environmental quality of the watershed, effective land use management and regional planning practices must be implemented."
In the Narragansett Bay watershed, the amount of land classified as urban increased from 350,369 acres in 2001 to 379,804 acres in 2011. The increase of 29,435 acres represented a net change of 8.5 percent. During the same time period, forest lands decreased from 443,800 acres to 424,642 acres, a decline of 19,158 acres or 4.3 percent. (NLCD)
Land-use changes in the Narragansett Bay watershed, especially the conversion of natural lands to manmade areas, impacts the resiliency of hydrological functions, alters the delivery of nutrients to rivers and the bay, affects terrestrial, aquatic and estuarine habitat conditions, and contributes to an increase of pathogens into recreational and shellfishing waters.
Quote: “The conversion rate of natural land cover to developed land has outpaced the population growth rate in this region over the last few decades.”
Quote: “In addition, a decline in forest lands indicates habitat fragmentation and less area to protect water resources.”
These subwatersheds have the highest percentage of impervious cover in the Narragansett Bay watershed. The middle column is the number acres, followed by the percentage of impervious surface. The bay's Big River, Scituate Reservoir and Barden Reservoir-Ponaganset River subwatersheds have the lowest percentage of impervious cover, at 3.2 percent. (NBEP)
Impervious surfaces are a known stressor of both water quality and water quantity, as pavement, buildings and concrete impact the natural hydrology and habitat condition of the watershed. Impervious cover promotes above-ground flow of stormwater directly into local waterbodies, rather than infiltration of runoff through the soil. This change results in more nutrients, pathogens and other pollutants entering waterbodies.
Quote: “There are numerous studies suggesting that watershed degradation increases substantially when impervious cover reaches a threshold of 10 to 20 percent of the watershed’s land area.”
Quote: “The amount of impervious cover in Narragansett Bay’s HUC12 subwatersheds demonstrates the considerable extent of urbanization around the Bay. Impervious cover exceeded the 10 percent ecological threshold in 36 of the 52 subwatersheds."
From 2013-2015, the 37 wastewater treatment facilities in the Narragansett Bay watershed discharged nearly 5.4 million pounds of nitrogen annually. (NPEP)
Nutrient loading refers to the input of nutrients into the ecosystem from numerous human sources, including centralized and on-site wastewater treatment facilities, stormwater runoff and air pollution. Phosphorus and nitrogen are naturally occurring nutrients in sewage. Such loading within the Narragansett Bay watershed has cascading negative impacts through the physical, biological and human-health indicators.
Quote: “The downward trend in total nutrient loading will likely improve the physical and biological health of ecosystems in the Narragansett Bay watershed.”
Quote: “The largest threat that nutrient loading (nitrogen and phosphorous) poses for a watershed is the potential for eutrophication.”
Spatial and temporal concentrations of metoprolol throughout Narragansett Bay. A recent study conducted over the course of a year showed elevated levels of numerous pharmaceuticals in the bay’s water column. Various pharmaceuticals, such as metoprolol, a beta-blocker used to treat high blood pressure, were present at all sites and sampling periods, confirming their widespread spatial and temporal distribution. (Cantwell et al. 2017)
Chemical contaminants of emerging concern (CECs) refers to chemicals that have been identified recently in natural waters that have no regulatory standards associated with them and can potentially cause adverse effects to aquatic life.
They include but aren’t limited to nonprescription and prescription pharmaceuticals, personal-care products, and industrial chemicals used in a wide range of consumer, commercial and industrial products. Some examples: antidepressants, antihypertensives, antibiotics, painkillers and synthetic hormones; antimicrobials such as Triclosan; UV blockers in sunscreens such as oxybenzone; DEET, a pesticide which is applied to human skin; fragrances such as synthetic musks; flame retardants such as polybrominated diphenyl ethers; additives to plastics; and synthetic materials such as bisphenol A, commonly referred to as BPA.
Wastewater treatment facilities were never designed to treat or remove CECs.
Quote: “The behavior and fate of CECs in aquatic systems are not well understood; consequently, the knowledge about the exposure risk from CECs to aquatic life and human populations is limited.”
Quote: “The Providence River, in particular, is an area of concern due to the daily volume of wastewater effluent entering this sub-embayment. This is also critical for other locations in Narragansett Bay, particularly where commercial, wild seafood harvesting, aquaculture activities, and human recreation are occurring.”
Frank Carini is editor of ecoRI News.