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Mill River Subwatershed Information

Municipalities: Boxford, Georgetown, Newbury, Rowley, Ipswich

Population: 5696

General Description: The Mill River is the largest tributary system of the Parker River and includes much of the Town of Rowley. Land use is primarily undeveloped and residential, although there are commercial/industrial areas along Route 1 and Route 1A. Additional commercial/industrial development is occurring along these transportation corridors and more is anticipated. Rowley’s Watershed Protection and Floodplain District is located in this subwatershed as are its existing and planned water supply wellfields. Concerns have been raised recently that the existing well fields adversely affect baseflow in the Mill River subwatershed.

Governor Dummer Academy is located near the tidal portion of Mill River. It has a wastewater treatment facility that discharges to an unnamed tributary of the Mill River. This wastewater treatment facility recently underwent significant modifications, which will result in improvements to the quality of the discharge.

Portions of the Georgetown-Rowley State Forest, Willowdale State Forest and Mill Creek Wildlife Management Area are located in this subwatershed. All tidal portions of this subwatershed are located in the Parker River/Essex Bay Area of Critical Environmental Concern. The Mill River once had an anadromous fishery (blueback herring and alewives), however the lack of a fish passage facility at the Jewel Mill (Glen Mills dam) impedes fish movement upstream to their
spawning habitat. Undeveloped land use declined from 8870 acres in 1991 to 8459 acres in 1999, while Residential land use has risen from 1643 acres in 1991 to 2558 acres in 1999.

Land Area: 11494 acres (18 square miles)

Land Use as of 1999: Undeveloped – 8459 acres (74% of the subwatershed, Forest is 58%)

Residential – 2558 acres (22% of the subwatershed)

Commercial/Industrial – 484 acres (4% of the subwatershed)

Named Tributaries: Ox Pasture Brook, Bachelder Brook, Great Swamp Brook, Muddy Brook.

Lakes and Ponds: Wilson Pond, Upper Mill Pond, Lower Mill Pond, Central Street Pond.

Rapid Watershed Assessment: The proportion of impervious cover in this subwatershed is estimated to be 5.3%. The water quality would be expected to be of high quality. While a comprehensive survey has not been done one would expect to find excellent habitat, diverse communities, and a stable stream channel. However, some localized impacts from summer low flow, road runoff, non-point source pollution and habitat alteration is likely. Additional impacts are expected with future growth, predicted by recently completed build-out analysis.

Water Quality Information: The Department of Environmental Protection Division of Watershed Management has included the Mill River, Great Swamp Brook, Bachelder Brook and Ox Pasture Brook in their water quality monitoring programs. The 1994 survey had 4 sampling locations on Mill River (plus 2 near Governor Dummer), one on Great Swamp Brook, two on Bachelder Brook and two on Ox Pasture Brook.

The Department of Environmental Protection did not conduct water quality sampling during the 1999 sampling year. However , biological monitoring was conducted at one station on Mill River and one station on Ox Pasture Brook in 1999. The Division of Marine Fisheries Shellfish Program last monitored water quality in the Mill River in 1994. Due to high bacteria the Mill River is classified as “Closed” to shellfishing. The Massachusetts Audubon Society conducted water quality sampling at 18 sites in this subwatershed as part of its Plum Island Sound Minibay Project and the Non-Point Source Comprehensive Implementation Program for the Mill River Subwatershed.

The Parker River Clean Water Association has located 3 sampling sites in this subwatershed (Jewel Mill, Route 1 at Elm Street, and Fenno Drive) as part of their volunteer monitoring program. Water quality is affected in this subwatershed from localized sources of bacteria from non-point source pollution, failed septic systems, cesspools, domestic animals and feral animals. Wilson Pond, Lower Mill Pond, and Upper Mill Pond are included on the Department of Environmental Protection’s list of waterbodies not in compliance with the state’s surface water quality standards. They are listed due to the presence of noxious aquatic plants. Non-point source pollution from agricultural sources to Mill River has been identified. Some of these sources are in the process of
being corrected through cooperative efforts by landowners, town and state and federal agencies.

Reported and identified water quality problems in the vicinity of Governor Dummer Academy have been addressed through a recent upgrade and operational improvements to the wastewater treatment facility at that property. Some sources identified through the Massachusetts Audubon Society’s Non-Point Source Comprehensive Implementation Program for the Mill River Subwatershed have been addressed.

Remaining pollution sources can be addressed by continuing to implement the septic system management program, by implementing best management practices
for road runoff and stormwater and by seeking to address the failing septic systems in Rowley Center. The biological assessment conducted by the DEP at the Mill River site in the vicinity of the Jewel Mill indicates generally very good aquatic habitat, however the macroinvertebrate community was rated as being “slightly impacted”. The biological assessment site on Ox Pasture Brook, near Fenno Drive, indicated excellent aquatic habitat and the macroinvertebrate communitywas rated as being non/slightly impacted.

Recommendations: Support the efforts of the Great Marsh teams, especially with regards to evaluating the potential of providing passage of anadromous fish to Mill River at the Jewel Mill or evaluating removal of the dam. Since a significant proportion of open space is not permanently protected it should be a priority to work with the Town of Rowley to identify priority areas for protection. The local open space and recreation committee should be encouraged to continue to
work closely with the Open Space Committee Network that was recently created.

Due to the identified water quality problems in this subwatershed the recommendations from the work conducted by the Department of Environmental Protection, Division of Watershed Protection and the Massachusetts Audubon Society should become a priority of the watershed team. These include outreach on septic system maintenance, inspections of septic systems in the known problem areas, implement best management practices related to stormwater control, improve baseflow in the Ox Pasture Brook tributary, conduct fish community and macroinvertebrate sampling in the Ox Pasture Brook tributary, evaluate the success of the septic system maintenance program, provide assistance to the problem site in the center of town and seek additional low interest loans through
DEP and others for septic system upgrades.

(Data obtained from the Executive Office of Environmental Affairs, Massachusetts Watershed Initiative, 2002 Watershed Assessment Report)

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