Nutrient Concentrations

Nutrient Concentration

How has the concentration of nutrients in the waters of Great Bay and Hampton-Seabrook Estuaries changed over time?

Dissolved inorganic nitrogen concentrations have been trending lower over recent years, despite higher levels between 1998 and 2016 for several stations. As a result, there are no increasing trends in dissolved inorganic nitrogen, but three stations have decreasing trends. Dissolved inorganic nitrogen is an important form of nitrogen because it is most readily taken up by eelgrass, seaweed, and phytoplankton. Total nitrogen is another form of nitrogen that incorporates particulate and living matter. Total nitrogen concentrations at Adams Point have significantly decreased since 2004, while Squamscott River is the only monitoring station that had a statistically significant increasing trend between 2003 and 2021. However, given the recent upgrade of the Town of Exeter Wastewater Treatment Facility, this trend may change in the near future. The Hampton River Station has the shortest time series and the second lowest levels of the seven stations listed.


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