Save the Bay Reports on Salt Marshes at Land Trust Meeting

by Laura Calverley

At the annual meeting of the Rehoboth Land Trust last month, Wenley Ferguson of Save the Bay gave a revealing presentation on salt marshes and how they are changing. The information she presented could have significant repercussions around the region, but especially for those landowners in the southern part of Rehoboth.

Save the Bay conducted initial assessments of salt marshes in Narragansett Bay, including the Palmer River, last summer. The assessments showed that salt marshes are subsiding and there are a number of possible reasons for it. “From doing restoration work in these marshes since the mid-90s, we started to notice how quickly marsh vegetation can change and it’s somewhat disturbing,” Ferguson said.

When the marshes subside and the proper vegetation can’t grow, it threatens wildlife that depend on the marshes including herring, shad, and some birds. Herring stock regionally has plummeted, says Ferguson. Local fishermen could also be affected because larger predator fish like striped bass and bluefish feed on fish that live in the salt marsh, such as salt marsh minnows. These minnows form the base of the food chain for the fish habitat.

“It’s important and it needs to be addressed,” said longtime Tree Warden Bill Dalpe.

There is also concern that the Salt Marsh Sparrow could soon be on the endangered list, says Ferguson. “The Salt Marsh Sparrow grows in the Spartina alterniflora that needs to be healthy and be a certain height so that the nest can be above the high tide.”

The marshes also act as buffers for the coastal areas, preventing storm damage and erosion.

Tide Restrictions Cause Phragmites to Grow and Damage Marsh Health

One of the main reasons for the marshes subsiding is tidal flow restriction. Restrictions such as road crossings restrict the flow between tidal water and the marsh.

“Marshes subside when the water gets impounded and the water doesn’t drain out because of the tidal restriction,” Ferguson said. That becomes a breeding ground for invasive plants, like non-native phragmites, which grows very densely and keep water on the marsh. Phragmites was a problem at Jacob’s Point at the mouth of the Warren River. Save the Bay conducted a restoration project there, installing new culverts which restored tidal flow, drained out the water, and eventually allowed the area to re-vegetate.

Sea Level Rising Affects Marshes

Another factor affecting marshes is an increase in sea level. Since 1930, there has been more than 25 centimeters of sea level rise and that is significant, says Ferguson. “Marshes can accrete, or build up, because they are so productive. They’re more productive than corn fields. But the accretion, or build up, rate is not able to compete with the sea level rise rate,” Ferguson said.

When the water starts ponding and cannot drain out, the marshes suffer. “When water sits on the marsh, the plants can’t adapt. They can’t grow in the water,” Ferguson said. “It takes two to three years for the vegetation and roots to begin to degrade.” Ferguson says that over the next 50 years, three to five feet of sea level rise is predicted.

The Effect of Roads and Other Impervious Surfaces

Another issue is the amount of impervious surface and runoff coming from pavement and roofs. In addition to the salt marsh assessment project, Save the Bay is also looking at low lying coastal infrastructure and shoreline areas that are impacted by flooding in order to identify different adaptation projects.

“The result of increased impervious surface (at one site) caused five meters of lateral growth of phragmites within two year,” Ferguson said. She says that there are many dead end roads in Rehoboth that are used as neighborhood access points to the Palmer River which may need to be looked at. “Often there is a lot of redundant pavement there and the pavement causes stormwater runoff into the river, causing water quality problems and erosion.”

Tides

Save the Bay has also been analyzing the tides and how they affect marshes. In the last three growing seasons, there have been higher than predicted tides, says Ferguson. “Up to 4 inches higher high tides and 4 inch higher low tides. That’s a lot of extra water coming into a salt marsh.” The additional water getting into the marsh is causing landscape changes to the wetland areas.

The Effect on Development and Infrastructure

The build-up of water in the marshes can also affect development in the area in the long run. “It could potentially negatively affect development that happens,” said Adam Latham, President of the Rehoboth Land Trust. The sea level rise often causes flooding on the roads and as it continues to rise over the years, the problem is expected to worsen.

“We have to prioritize which sites we need to protect, what roads need to be raised, and what sites will need alternate access,” Ferguson said. She says there are a lot of challenges ahead for towns in regards to adapting to the changing sea level rise and flooding. In many areas there’s no room for marshes to move inland because they are developed. These issues are also important to possible future development.

Conserving and Protection Rehoboth’s Open Space

Rehoboth is fortunate because it includes a lot of open space, and the Palmer River is unique because it is one of the few undammed rivers in the region. There is more opportunity for the habitat to adjust to the higher sea level, says Ferguson. “Because these lands are undeveloped, there’s an opportunity to protect them and make sure they remain open space so that these low lying marsh areas which today are salt water have the ability to move inland,” Ferguson said. “We’re seeing impact to these marshes today and it shows how vulnerable and fragile they are. It underlines the importance of protecting these marsh areas and habitats for today and for the future - for wildlife habitat, for fish and birds, for health of ecosystem, for erosion control, and for the community, as recreational fisheries, and just for the beauty of these areas.”

The Rehoboth Land Trust is dedicated to preserving open space for farming, resource protection, and recreation, as well as helping farmers and landowners on these projects. The Rehoboth Land Trust currently owns 125 acres and recently helped purchase a conservation restriction on 89 acres of property at Oak Hill Beagle Club. The Land Trust teamed with the Agricultural and Natural Resources Council, the Community Preservation Committee, the Conservation Commission, and the Trustees of Reservations on the project.

“If we’re able to protect the area with APR (Agricultural Preservation Restriction) and conservation restriction, then it’s good because with APR, families can continue to farm and gain capital. It also protects land from development and negates potential negative impact from the rising river,” said Latham.

For More Information

Anyone interested in information on protecting land on their property can contact the Rehoboth Land Trust, Conservation Commission, Town Planner, or Save the Bay.

There are federal assistance programs available for land protection. The National Resource Conservation Service website, www.nrcs.usda.gov, outlines some of the programs available. One of the programs, the Environmental Quality Incentives Program (EQIP) provides financial and technical assistance through contracts to help plan and implement conservation practices that address natural resource concerns and to improve soil, water, plant, animal, air, and related resources on agricultural land and non-industrial private forestland. Another program, the USDA’s Wetland Reserve Program, provides technical and financial assistance to help landowners restore and protect wetland ecosystems. In the twenty-year history of the program, more than 11,000 landowners have participated and more than 2.6 million acres of wetlands habitat have been restored.