Condition and trends of estuarine water quality in Gateway National Recreation Area: Northeast Coastal and Barrier Network, 2003–2022

Nagel, Jessica; Paisted, Holly; Peck, Christopher; Duffy, Paul

doi:10.36967/2310870

This report summarizes conditions and trends in routine long-term water quality monitoring data collected at Gateway National Recreation Area in New York from 2003 through 2022 as part of the NPS NCBN Vital Signs Estuarine Nutrient Enrichment monitoring program. This comprehensive program incorporates spatial surveys, repeated monitoring at trend stations, and continuous monitoring at a fixed logging station in an effort to establish overall condition of the estuary as well as to identify potential trends or changes in condition over time. All monitoring was conducted during a four-week summer index period within the Jamaica Bay subunit of the park. Monitored variables included dissolved oxygen concentration, chlorophyll-a concentration, attenuation of downwelling photosynthetically available radiation (PAR), salinity, temperature, turbidity, and pH. Condition and trends were generally consistent between the spatial station surveys, the trend stations, and continuous logging station. Despite a significant decline in turbidity, water clarity, as measured by PAR attenuation, across the estuary was generally classified as being in fair condition, with no significant change observed over time. Although declines in chlorophyll-a concentrations were observed over time, the majority of the estuary was classified as being in poor condition in most years sampled, and the area-weighted mean was consistently greater than 20 µg/L indicating poor condition overall. While the majority of the estuary was consistently classified as being in good to fair condition with respect to bottom dissolved oxygen concentrations, concentrations throughout the estuary exhibited a significant decline. There was a significant increase in water temperatures at the trend stations, and temperatures in the majority of the estuary exceeded 25°C for most years. Spatially, water quality and clarity conditions were worse along the intensely developed northern shoreline of the bay closest to New York City. Given the observed significant decline in bottom dissolved oxygen concentrations, significant increase in temperature, and poor chlorophyll-a conditions, the continued monitoring of estuarine nutrient enrichment vital signs will be essential for managers to make informed decisions, develop effective mitigation measures, reduce management costs, and provide a means of measuring progress towards goals.

Condition and trends of estuarine water quality in Gateway National Recreation Area: Northeast Coastal and Barrier Network, 2003–2022

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