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1996 Citizens Report: Wareham River

Embayment: Wareham River

Embayment and Watershed Characteristic

The Wareham River drainage basin is the third largest in Buzzards Bay, and overall one of the least developed. Percent agricultural land coverage (mostly cranberry bogs) is close to the median for the embayments studied. Housing density is relatively low, but because of the large basin size, total housing units and population was among the highest around Buzzards Bay. The eastern Branch of the Wareham River estuary is fed by the Agawam River into which discharges the Wareham sewage treatment plant which serves areas outside the Wareham and Agawam River basins, including the town of Bourne. Therefore this estuary is receiving nitrogen loadings in excess of what occurs in the watershed. This point source accounts for more than 25% of the total nitrogen load to the embayment, and oxygen data from monitoring stations on the Agawam River are discussed on page 47. New areas of Wareham have been connected to the treatment plant in recent years. The Broad Marsh River complex is actually a subestuary of the Wareham River, but is discussed in the following section. As might be expected, patterns of water quality in the Broad Marsh River parallel that of the Wareham River. Marks Cove, another embayment branching off near the mouth of the Wareham River is discussed in this section. The Buzzards Bay Project completed a separate subwatershed evaluation for Marks Cove, but the results of the Citizens Monitoring Program suggest that Marks Cove cannot be managed separately from the Greater Wareham River Complex.

Results of the Citizens' Water Quality Monitoring Program suggest that the Wareham River is among the most eutrophic estuaries in Buzzards Bay. The Upper portions of the Wareham River are closed to shellfishing because of fecal coliform contamination.

Water Quality monitoring

Total nitrogen concentrations in the Inner Wareham River were high, ranging from 0.55 ppm to over 0.8 ppm. The highest concentrations were observed in 1994 where all three constituents of total nitrogen (dissolved inorganic, dissolved organic, and particulate organic) showed marked increases. Down River in the outer estuary, total nitrogen concentrations were better in three years, ranging from just under 0.4 ppm to a high of just under 0.6 ppm, but in 1994 concentrations of total nitrogen approached 0.9 ppm, including a tripling of inorganic nitrogen concentrations. The consistency between upper and lower estuary nitrogen values suggest some unknown nitrogen loading event or events were documented in that year. This phenomenon was not limited to forms of nitrogen, but a large increase of phytoplankton was also observed in the inner harbor with a low under 5 ppb in 1992 to a high over 15 ppb in 1994. Patterns of chlorophyll in the outer river precisely mirrored year to year changes in the inner estuary, but at 20-30% lower concentrations.

Oxygen concentrations were somewhat more consistent over the study period as exemplified by station WR1. Here % saturation levels were consistent between 1992 and 1994, but showed a marked drop in 1995. Some other parameters such as dissolved inorganic nitrogen showed some abrupt fluctuations, and Eutrophication Index scores ranged from 31 to 52 points, earning a "poor" Eutrophication Index score for one of the four years of study.

Marks Cove mirrored somewhat the pattern in the larger estuary, but apparently was also influenced by more local nitrogen inputs. During the four years of study, total nitrogen concentrations steadily rose from 0.4 to 0.8 ppm. Phytoplankton also increased dramatically, but like the Wareham River, highest concentrations were observed in 1994, and approached the 15 ppb observed in the upper estuary. Dissolved inorganic nitrogen concentration nearly tripled in 1995. Because oxygen was not monitored in Marks Cove, Eutrophication Index scores are unavailable for that part of the Wareham estuary.

Eutrophication Index scores

Nitrogen Management needs

The land use evaluation suggests that the Wareham River is 100% over recommended nitrogen loading limits now, and will more than double at future buildout conditions. The water quality monitoring results paint a better picture, but clearly nitrogen management is needed, particularly in light of continued increased flows to the Sewage Treatment Plant. Nitrogen loading to the Wareham River estuary is nearly evenly split between residential land, the sewage treatment plant, agriculture (cranberry bogs), closely followed by commercial and industrial development, and all these sources must be included in a comprehensive management strategy. The town of Wareham is now in the early stages of planning for upgrades in the town's wastewater treatment plant and regulatory agencies like the US EPA and Massachusetts DEP are considering imposing nitrogen limits as part of the plants discharge permit scheduled for renewal in 1997. The Wareham River is now well over SA limits, and nitrogen loading could more than double at full buildout. Adoption of an SB designation for the Wareham River estuary will require a less challenging management strategy to be implemented for the estuary and may be appropriate in light of the sewage Treatment Plant discharge.

Marks Cove has one of the smaller embayment drainage basins in Buzzards Bay, but one largely composed of residential parcels. The residential land accounts for 67% of the total nitrogen load to Marks Cove. Part of the embayment is sewered and overall Marks Cove at first glance would appear to have a relatively low nitrogen loading rate, but clearly the water quality in Marks Cove largely reflects the more degraded conditions in the Wareham and Agawam Rivers.



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