The short version
This was the Massachusetts Estuaries Project’s first report on Waquoit Bay. It covered three eastern arms of the bay in Mashpee and Falmouth: the Quashnet River, Hamblin Pond with the Little River, and Jehu Pond with the Great River. It found all three harmed by nitrogen, with the upper Quashnet River severely degraded, and set the first nitrogen targets for them. Its most important lesson is that these arms share water with the main bay. Unless the main bay gets cleaner too, local cleanup alone can’t bring back eelgrass in Jehu Pond.
What the researchers did
The Massachusetts Estuaries Project, a partnership of MassDEP and the University of Massachusetts Dartmouth’s School for Marine Science and Technology (SMAST), uses a standard approach for each estuary. Brian Howes and colleagues applied it here with support from the Town of Mashpee, Barnstable County, MassDEP and the US EPA.
- They estimated nitrogen from every source in the watershed using land use and water-use records, and measured flow and nitrogen in the Quashnet River and Red Brook.
- They built tidal and water-quality models of each sub-estuary, calibrated with years of monitoring data collected largely by Mashpee and Reserve volunteers.
- They judged habitat health from oxygen, algae (chlorophyll), eelgrass history and bottom-dwelling animals, then used the model to find nitrogen levels that would restore each area.
What they found
- The Quashnet River is in the worst shape. Chlorophyll in its upper and middle reaches averaged more than 20 micrograms per liter, with blooms above 140. Bottom samples held only 0 to 18 animals each, compared with hundreds to thousands at healthy sites. The upper river was rated severely degraded.
- The ponds are impaired but less so. Jehu Pond was rated significantly impaired, with low oxygen at times and chlorophyll averaging 11.9. Hamblin Pond was moderately impaired, averaging 7.4. The Little and Great rivers had healthier bottom habitat.
- Septic systems are the biggest single source. Wastewater returns to the ground almost entirely through septic systems, apart from two small private treatment plants in the Quashnet watershed.
- New targets. The report set total nitrogen targets of 0.50 mg/L for the Quashnet River, to restore bottom habitat; 0.446 mg/L for Jehu Pond; and 0.38 mg/L for Hamblin Pond, to restore eelgrass.
- The main bay is the catch. Water flooding in from Waquoit Bay already exceeded 0.38 mg/L. In a scenario that removed all septic nitrogen from the Jehu and Hamblin watersheds, Jehu Pond fell only from 0.603 to 0.466 mg/L, still short of its target.
- What it would take. With the main bay at 0.35 mg/L, the targets could be met by removing about 75% of septic nitrogen in the Hamblin Pond watershed, all of it in the Jehu Pond watershed and about 67% in the Quashnet River watershed.
What it means for Waquoit Bay today
The authors concluded that nitrogen management for these waters must focus on restoration, not protection or maintenance of existing conditions
(Howes et al., 2004). Their finding that the eastern ponds depend on the main bay is why Falmouth and Mashpee have to plan together: nitrogen from either town’s side affects the water the other town’s ponds receive.
The report said all three areas would be re-evaluated in a full study of the bay. That study, the 2013 MEP report for Waquoit Bay and Eel Pond, set the limits used in today’s wastewater plans (see our explainer on the state’s threshold report).
Read the report
Howes, B., Kelley, S. W., Ramsey, J. S., Samimy, R., Schlezinger, D., Ruthven, T., & Eichner, E. (2004). Linked Watershed-Embayment Model to Determine Critical Nitrogen Loading Thresholds for the Quashnet River, Hamblin Pond, and Jehu Pond, in the Waquoit Bay System of the Towns of Mashpee and Falmouth, Massachusetts. Massachusetts Estuaries Project, Massachusetts Department of Environmental Protection, Boston, MA. Final report dated January 2005. https://www.mass.gov/doc/quashnet-river-hamblin-pond-and-jehu-pond-in-the-waquoit-bay-system-of-the-towns-of-mashpee-and/download
License: A Massachusetts Department of Environmental Protection and UMass Dartmouth SMAST report. It is not openly licensed, so we link to the official copy on Mass.gov rather than hosting one.
Drafted with AI assistance from the linked source.
