How We’re Restoring Marshes

Marsh restoration overview

August 18, 2025

As stunningly beautiful as Maine’s tidal marshes may be, many of them don’t actually look the way that a marsh should naturally look. Colonial farming practices left them ditched and drained in some places, and waterlogged in others, erasing central channels that should flood and empty with each tidal cycle.

To help Maine’s marshes return to their natural state, MCHT is working with the Maine Tidal Restoration Network and a regional collaboration called SMARTeam (Salt Marsh Adaptation and Resiliency Team). Together, we are working to not only improve marsh health today, but also help improve chances of successful marsh migration as sea levels rise in the decades to come.

We begin each restoration project with a site assessment that includes meeting with impacted landowners and creating an in-depth map of agricultural features identified on the marsh. We then implement a combination of the following techniques, tailored to the needs of a given site.

Ditch remediation

Farmers dug deep ditches across tidal marshes to control the flow of water and increase hay productivity. Over time, abandoned ditches left marshes waterlogged and unhealthy.  

To fill in these scars, we begin by mowing grasses along the banks of a ditch and then rake that material into the bottom of the ditch, securing it with stakes and twine. As this organic material decomposes, it provides a surface for new grasses to sprout from. We return the following year to repeat the process, this time mowing on the opposite bank to minimize disturbance. We repeat this over the course of three or four years until the ditch fully fills in with sediments and newly growing grasses. 

Runnel digging 

Marsh plants can withstand some level of flooding, but their roots also require periodic exposure to air to remain healthy.  

To help drain waterlogged areas of marsh and increase plant productivity, we dig wide and shallow runnels that allow water and sediments to flow in and out of the system with each tidal cycle. We dig the runnels either by hand with shovels, or by driving a standard excavator over weight dispersal mats that limit our impact on the marsh grasses and sediments below. As we progress across a marsh, we pick up the mat and leap frog behind it, leaving behind grasses that easily spring back up once we depart the site. 

By digging runnels that are wide and shallow—unlike the deeper ditches dug by farmers—we help improve the flow of water into and out of the marsh, and also help keep carbon buried underground.