Answer: While progress has been seen in past years, the 2020 sediment quality assessment indicates that the area of toxic sediments may be increasing. Efforts made to understand and reduce legacy contaminants like polychlorinated biphenyls (PCBs) have helped but there is a need for additional work on emerging contaminants to determine effective reduction strategies. Actions associated with this objective promote further work.
*The Objective’s Measure of Success define reasonable outcomes and ensure that progress towards the Objective can be clearly and precisely tracked over time.
Based on the Measure of Success, the overall status of this Objective is:
The objective is uncertain because we do not have current data to make an assessment. While there is a decreasing trend in good sediment quality from 2015 to 2020; there was an increasing trend experienced in previous years (i.e., 2005 to 2015). The EPA NCCA surveys every five years – while capturing long term trends, toxic contaminants in sediments can change rapidly due to acute events like storms and other disturbances that resuspend sediments into the water column. The Long Island Sound Partnership is investing in not only increasing the number sampling events, but also sample numbers. Through this data collection, more analyses will be conducted to identify trends as well as causes and impacts.
The primary measure of success is to increase the area of sediment in good condition in Long Island Sound by 20 percent from the 2005 baseline by 2035. The area of sediment in good condition in Long Island Sound from the 2005 NCCA was 53 percent. This goal, if achieved, would raise the proportion of sediment in good condition from 53 percent to 64 percent, which is both ecologically significant and technically feasible based on past trends and ongoing management efforts.
The Sediment Quality Index (SQI) from EPA 2020 NCCA for Long Island Sound (23 spatially-weighted sampling sites), showed that sediment condition was good at 56 percent of the sites, fair at 23 percent of the sites, and poor at 21 percent of the sites. This compares with the 2015 Assessment for Long Island Sound (22 spatially-weighted sampling sites), which showed that sediment condition at 72 percent of the sites was good, 23 percent of the sites fair, and 5 percent poor. While the data shows a decrease in sediment quality from 2015 to 2020, the data also shows significant improvements from 2005 to 2025 specifically in the 2015 survey as 72 percent of sediment quality to be in good condition. While further research is necessary to identify direct causes for the decline and potential impacts of poor sediment quality, changes in environmental conditions, such as increased storm frequency and intensity and changes in upstream river conditions, may have impacts.
It is important to note, while many existing aquatic contaminants have been reduced through the National Pollution Discharge Elimination System’s (NPDES) permit limits and other corrective actions, residual and legacy contamination may persist. Thus, further monitoring, assessment, and mitigation may be necessary to achieve this objective.
Further research is necessary to inform toxic contaminant reduction strategies going forward. More specifically, the Partnership is focused on better understanding and assessing the contribution and impacts of emerging contaminants such as polyfluoroalkyl substances. Under the 2025 CCMP, the Long Island Sound Partnership’s, Clean Water and Healthy Watersheds Working Group plans to prepare a Toxic Contaminants Actions Agenda, which will establish actions to reduce toxic contaminants – both legacy and emerging – that the Partnership can take.
The scope of emerging toxic contaminants is large and evolves rapidly at times. Research and monitoring are necessary for source identification, evaluating best management practices, reduction strategies, and preventative actions that may require significant investment. This scope and continuous change and evolution in our understanding of toxic contaminants will inevitably be a significant challenge to addressing this objective.
Additionally, increasing storm frequency and intensity may also pose a challenge as these events may resuspend and transport legacy toxic contaminants back into the aquatic environment where they may be more bioavailable and have a greater impact on aquatic life .
Furthermore, the EPA NCCA is currently conducted only every five years. The current number of sampling locations in the open Long Island Sound is considered too low for good statistical significance; 50 locations in the open Sound would be required for such significance.
Toxic contaminants can occur in the water column and sediment of Long Island Sound and its embayments. This includes “legacy” contaminants, such as heavy metals, pesticides, polychlorinated biphenyls (PCBs), and polycyclic aromatic hydrocarbons (PAHs); as well as emerging contaminants, such as per- and polyfluoroalkyl substances (PFAS), pharmaceuticals, personal care products, and nanomaterials.
Toxic contaminants have the potential to harm aquatic organisms at various life stages, including early development and reproduction. These contaminants may further pose a threat due to their persistence and bioaccumulative characteristics, as well as through chemical reactions and transformations that may occur in estuarine waters. Additionally, emerging contaminants are increasingly being detected in surface waters and the extent of their impact is not fully understood but is expected to be significant.
Kelly Streich, CT DEEP, kelly.streich@ct.gov
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These are long-standing pollutants or chemicals that were used and released into the environment in the past and persist today continuing to threaten ecosystems and human health. Examples include PCBs, DDT, lead, and mercury. They are often the result of industrial, agricultural, or urban activities and break down very slowly.
These are chemicals or substances that have recently been detected in the environment and are not yet fully understood. They may not be new to the environment but new information on their impacts is being gathered. They include pharmaceuticals, personal care products, microplastics, PFAS, and new industrial chemicals, and pose a risk to human health and ecosystems.