The Herring River Estuary was a great salt-water tidal marsh flowing into and out of Cape Cod Bay. In 1909, the Herring River was diked in the hopes of providing relief to vacationers of pesky mosquitos breeding in the salt marsh. As those vacationers were critical to the region’s economy, construction of the dike was much heralded; however, by significantly reducing the tides and exchange of water within the estuary, other changes occurred which upset the health of this sensitive ecosystem. The ecological impact of the dike was, indeed, significant. Some of these changes resulted in reduced oxygen levels and increased acidity in the water, causing significant harm to the habitat of fish and crustaceans. Fresh water plants and species invaded the ecosystem, replacing native marine plants that formerly thrived over large areas. Hundreds of thousands of migratory fish—and almost all aquatic life in the estuary—suffered the effects of diminished water quality, including fish kills. And while fish kills are a thing of the past, today the numbers of migrating fish are significantly diminished and the wetlands remain affected by restricted tidal flows. Unless steps are taken to adapt, rising sea levels may result in further harmful effects on the natural ecosystem.
Our nation has learned a lot since 1909. We now recognize the vital role of tidal flows to the health of coastal ecosystems and migratory fisheries, and in turn, the importance of a healthy ecosystem to the local community, economy, and thousands of annual visitors who enjoy its lands and waters. Partnering with the Friends of Herring River, the towns of Wellfleet, as well as Truro, and the Herring River Restoration Committee (comprising the Cape Cod National Seashore and several federal and state agencies), Fuss & O’Neill is designing improvements to the century-old dike to restore tidal flows and support the future health of the estuary.
Our team undertook one of the largest restoration efforts of its kind, designing the planned Chequessett Neck Road Bridge. Our design for this structure provides gates that will enable adaptive control of tidal flows as restoration of wetland communities advance with incrementally increasing tides and will significantly improve public access to the adjacent waters and wetlands. The design involves replacing a portion of the Chequesset Neck Road causeway with a 167 foot long bridge, which will be equipped with fishing platforms and innovative removable flow control panels that best enable the community to manage future changes to the estuary. A “green” structure, the bridge will use “low impact design” (LID) practices to improve treatment of stormwater flowing onto the causeway and further protect this valuable resource.
What is an estuary? In the case of the Herring River Estuary, it is where fresh and saltwater now mix.