Background

Fecal coliform (FC) indicates the presence of raw or partially treated sewage. Although not harmful to human health itself, FC is found in the intestinal track of all mammals and is correlated with bacterial, viral and parasitic human pathogens, giving an indication of the disease causing potential of the waterways.

Since the passage of the Clean Water Act (CWA) in 1973, long-term trends indicate a significant reduction in FC in New York Harbor. A number of factors contribute to this reduction including secondary treatment of sewage at all but one of NYCDEPs water pollution control plants, operational improvements at WPCPs that increase dry and wet weather capture and treatment, and continued abatement of illegal discharges.

In New York Harbor, FC measurements are typically higher following periods of significant precipitation due to direct runoff and sewer overflows. FC measurements often vary by orders of magnitude due to the event driven nature of the sources and that their distribution can be uneven, concentrated in some spots and dispersed in others. For this reason, summer geometric means are best suited to analysis of temporal and spatial trends for FC. Values are expressed as number of cells per 100 milliliters of water (cells/100ml). Surface FC results are presented in this report. Bottom samples were taken from 1986-2000 but are not presented, as these values are regularly lower than surface FC.

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Results

Fecal coliform levels have fallen dramatically over the past thirty years in New York Harbor. From 1973-1977, the average summer geometric mean for FC was 3923±360 cells/100ml. Since 1996 to the present, FC levels have fallen to 62±15 cells/100ml, well below regulatory thresholds for recreational use.

The Inner Harbor and the Upper East River/ Western Long Island Sound regions have seen the most dramatic improvements in pathogens in the harbor. In the Inner Harbor, average summer geometric means have fallen from nearly 5,000 cells/ 100ml in the mid-1970s to under 70 cells/100ml over the past eight years (Figure 5–1).

Much of the major reductions in FC in New York Harbor corresponded with the completion of primary and secondary wastewater treatment plants. On the Hudson River, the completion of the North River WPCP in 1986 and completion of secondary treatment in 1991 marked the beginning of a period of rapid water quality improvement. Fecal coliform has declined several orders of magnitude on the Hudson River and Inner Harbor over this time period.

Despite this widespread improvement, several regions in the Harbor are still problematic. Narrow straights including the Harlem River and the Kills have summer averages four to five times greater than the Harbor as a whole. Confined basins such as Newtown Creek and Gowanus Canal also see frequent spikes in FC corresponding with heavy rainfall and CSO events.

In summer 2003, monthly FC geometric means for New York Harbor were in-line with ten-year averages. However, FC levels spiked in June and September in several regions of the harbor, corresponding with above average rainfall in those months.

In June, FC monthly geometric means spiked in the Upper Bay (325 cells/100mL) and the Kills (300 cells/100ml). In the Upper Bay, the regional monthly mean was affected primarily by the high levels of FC in Gowanus Canal (G2), which had a June monthly mean of 928 cells/100ml. In the Kills several locations spiked above their ten-year June averages including Shooters Island (K2), Fresh Kills (K4), and Tottenville (K5). B&O Coal Dock (K1) and B&O Railroad Bridge (K3) have much higher June averages, in the range of 500-600 cells/100ml, however the 2003 results agreed with ten-year June norms.

The Harlem River, with only one sampling site (H3), experienced high levels in June (314 cells/100ml) however, this result was actually below the ten-year June average of 511±634 cells/100ml. Despite the improvement in 2003, the Harlem River continues to have high FC levels relative to other parts of the Upper East River and Western Long Island Sound.

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