The Three Bays Watershed, located in the Towns of Barnstable, Sandwich, and Mashpee, is facing a crisis of water quality degradation. Excess nitrogen has been identified as the largest contributor to water quality degradation throughout Cape Cod including the Three Bays (Cape Cod Commission, 2015.) Residential waste water systems and non-point sources of pollution including stormwater runoff, and excess fertilization, are identified as the three primary sources contributing 77%, 13% an 10%, respectively, of the excess nitrogen flowing through groundwater and into the bays. Like other watersheds throughout the Cape, Three Bays is largely a residential watershed with 92% of its parcels zoned for residential use. In addition to nitrogen contamination, water quality degradation is recognized to have significant ecological, economic, and cultural impacts on the health and quality of life in the watershed. Applications of ecological planning, design strategies, and best practices at multiple scales, from watershed to parcel, create opportunities to improve the ecological health and quality of life throughout the watershed. Research in ecological design and cultural perceptions of landscape help inform the development of conceptual residential ecological designs. Three residential parcel districts, Freshwater Waterfront, Saltwater Waterfront, and Upland Neighborhood are used to frame typical parcels. Within these parcels, conceptual ecological landscape designs are displayed that provide multiple ecosystem services to improve watershed health while honoring aesthetic and cultural norms, and possible expectations of the watershed. Recommendations discuss potential impacts of a parcel by parcel approach to watershed planning and describe water quality improvement scenarios under varying levels of participation and consequent reductions of nitrogen in the watershed.