Three Bays Estuary (barnstable, Cape Cod) Watershed Restoration Plan: a Green Infrastructure Aproach

This paper presents an approach described as “non-traditional” for restoring water quality and ecosystem services that have been degraded as a result of excess nitrogen. It focuses on emerging technologies often referred to as green infrastructure. These technologies may provide cost effective alternatives to traditional, gray infrastructure such as sewering and is likely to provide significant co-benefits including the creation of local jobs, the preservation of real estate values, and habitat enhancement.

The paper focuses on the Three Bays estuary on Cape Cod to illustrate the benefits and potential of green infrastructure technologies. The Three Bays estuary is presented as a case study and as a representative example of implementation of the broader Cape Cod Water Quality Management Plan Update (208 Plan Update) – a nationally-recognized watershed planning project designed to provide a pathway for the fifteen towns of Cape Cod to achieve compliance with Section 208 of the Clean Water Act.

The Three Bays estuary and embayment system is a scenic Cape Cod bay that hosts sailing, kayaking, swimming and shellfishing and is located in the Town of Barnstable. It is comprised of three primary segments that include West Bay, North Bay and Cotuit Bay. Sub-systems include Prince Cove that flows into North Bay, the Narrows that flows between North Bay and Cotuit Bay and Eel Pond that flows into East Bay (see Figure 1).

The Massachusetts Estuaries Project (MEP) is a state-sanctioned watershed-modeling project that assesses the conditions of the state's estuaries and required restoration goals. Its technical report (2006) indicates that the water quality of the Three Bays system has resulted in seriously degraded to moderately degraded habitat. The system is listed as an impaired water body on the US Environmental Protection Agency (EPA) 303d list of impaired waters. An approved Total Maximum Daily Load (TMDL) for nitrogen has been established for the embayment.

This assessment is supported by more recent empirical water quality data collected within the embayment. The more current data documents a continuing decline in water quality with more common algae blooms (see Figure 2).