Bay Plan Challenges Towns: Climate Change Impacts May Be Dire

PLEASANT BAY – The first paragraph in the first section of the Pleasant Bay Alliance’s Pleasant Bay Climate Action Plan spells out what’s at stake as the Cape’s largest estuary faces the potential of severe impacts due to climate change.

 Along with being a state-designated Areas of Critical Environmental Concern, the 7,000-acre bay includes 71 miles of shoreline, three tidal rivers, four islands, and is connected to 11 freshwater ponds. The bay’s watershed covers 21,000 acres in Chatham, Harwich, Brewster and Orleans, the four towns that border its shoreline.

 Many of the resources within the bay, considered one of the most biologically diverse and productive marine habitats in the northeast, could be endangered by rising tides and increased water temperatures due to climate change, according to the plan. Sea level rise — between four and eight feet by 2100 — and projected increases in water temperatures — as much as 20 degrees by 2050 — could result in the loss of nearly three-quarters of the bay’s intertidal resources, including salt marsh and eelgrass. Both, the plan notes, provide habitat, buffer storm surges, filter pollutants and store carbon and are “susceptible to changes in water level and water temperature.”

 And that’s not all. According to the plan, public infrastructure, including town landings, water mains and sewer pump stations along the bay also face threats due to climate change.

 “These climate effects threaten our ability to access and enjoy the waters of Pleasant Bay, and they also affect the bay’s ability to function as an estuary and contribute to the sustainability of our oceans,” the plan’s executive summary concludes.

 These are not revelations, but the stark language and predictions in the study are bright red warnings to local towns that they need to take steps now to plan for the worst.

 “I think we’re seeing changes already, and we could continue to see them happen at a fairly quick rate,” said Carole Ridley, coordinator of the Pleasant Bay Alliance, which is composed of the four towns that border the bay.

 The climate action plan, released over the summe provides strategies and tools that local towns can adopt to make facilities more resilient, support restoration and rehabilitation of salt marsh and eelgrass, promote climate resilient regulations, policies, infrastructure planning and design, and engage the community to create buy-in from the public.

 “We now have a blueprint, a gameplan moving forward,” Ridley said.

 The plan provides science-based information to back up that blueprint, she said. It includes information that the Alliance developed in 2017 on sea level rise and the Nauset/North Beach barrier, as well as an assessment of the bay’s salt marshes, in conjunction with the Center for Coastal Studies (CCS) in Provincetown. With a 2022 state municipal vulnerability preparedness grant, the Alliance worked with CCS and a number of regional and town organizations to update the previous analyses, identify priorities and develop action recommendations.

 The recommendations are based on the more conservative sea level rise estimate of four feet by 2100. The upper end eight-foot estimate “takes some measures off the table” due to its severity, Ridley said. That would not have been productive, and using the low estimate makes allowances for measures that are more flexible and can be adopted over time.

 “But if you’re planning everything for eight feet, you won’t be able to do much,” she said.

 The effort had four main tasks: assess the impact of climate on the bay and its resources; assess impacts on public access sites and water, wastewater and stormwater infrastructure; assess climate impact on eelgrass and salt marsh; and build awareness of climate threats facing the bay and convey the resilience priorities in the plan.

 The study looked at erosion along the outer beach as well as storm tide pathways, narrow, low-lying areas that are likely to convey coastal flood waters inland. Some 105 potential pathways were identified in Harwich, Chatham and Orleans (none in Brewster, although the study points out that the other pathways have the potential to flood areas within Brewster), with 13 found to be just one foot above the highest recorded storm levels, with the potential to flood some 250 acres. “It is unlikely that local managers are prepared for this extent of flooding that could occur as a result of a one foot increase in water levels,” the report reads.

 Eight of the 60 public access points throughout the bay were evaluated for risk and remedies related to sea level increases. These included three public accesses — Meetinghouse Pond pier in Orleans, Crow’s Pond and Cow Yard landings in Chatham — water mains in Orleans, Brewster and Harwich, a wastewater pump station on Harden Lane in Harwich, and the stormwater treatment system at Lonnie’s Pond in Orleans.

 The landings are likely to be subject to increased erosion, submergence and loss of parking; in addition, both the Crow’s Pond and Cow Yard landings open up Fox Hill Road and Old Harbor Road to flooding, potentially cutting off access for some residents. The roadways should be evaluated, including emergency access measures, before significant investment is made in upgrading the landings, the plan recommends.

 At Meetinghouse Pond, new boat storage should be built and salt marsh should be restored where the current walkway and boat storage is located, according to the plan.

 Much of the bay’s eelgrass, which functions as a nursery for many species, especially shellfish such as scallops, has already died off. Under the conservative four-foot sea level rise scenario, by 2100 72 percent, or 294 acres, of the bay’s intertidal resources, including salt marsh, will be lost.

A demonstration project to restore salt marsh is underway at Jackknife Harbor. The “living shoreline” project’s goal is to stabilize and restore the marsh along the banks of Muddy Creek. The process uses some innovative elements, including shellfish to stabilize the existing and new banks and sills to redirect tidal current away from marsh. Some of these methods have never been used in Massachusetts before.

The project, expected to cost around $400,000, has been fully permitted, according to Chatham Coastal Resources Director Ted Keon, and is awaiting final funding through a state Coastal Zone Management Coastal Resilience Grant. The town has already appropriated $100,000 in community preservation funds to serve as a match for the grant, he said.

 The plan warns that climate change isn’t just “it’s own thing,” Ridley noted. “It applies to just about everything” that local towns do and needs to be taken into consideration in virtually all local towns’ decision and policy making. It recommends that wetlands, zoning and other local regulations be evaluated with climate change in mind.

 Taking no action will likely impact how people enjoy the bay in the future, Ridley said.

 “We may lose some of our fringing marsh areas, we may have access locations that are inaccessible during certain conditions and certain times,” she said. 

 The Alliance plans to reach out to town officials and committees to familiarize them with the information and tools in the plan, she said. The document can also provide support and integrate with work being done by the Cape Cod Commission on low-lying roads and model bylaws, she added.

 “We have the opportunity to take action,” she said. “We look forward to more conversations with community partners on how to move our recommendations forward.”

 The full plan can be viewed at pleasantbay.org/wp-content/uploads/Pleasant-Bay-Report-May-2024.pdf.