This is a tidal river with extensive saltmarsh in the upper portion. Because of tidal restriction at Buttermilk Lane, the marsh above this road is more brackish, lacking large expanses of Spartina that characterize much of the saltmarsh. This site is best known for its abundance of pannes and overall surface complexity. The land surrounding the marsh is largely undeveloped despite its close proximity to Thomaston and Rockland. A large cement factory is located within a mile of the site. The marsh is largely surrounded by forest, but agricultural fields border the marsh on portions of its eastern periphery. Extensive tidal flats are found in the lower portion of the river.
The marsh supports significant numbers of migratory shorebirds, waterfowl, wading birds, and breeding wetland species. The northernmost known breeding site for Saltmarsh Sharp-tailed Sparrow occurs here along with an abundance of Nelson?s Sharp-tailed Sparrow. The marsh is an important area for observation of shorebirds (part of PRISM shorebird monitoring network) and is especially good habitat within the state for Stilt, Western, and Baird?s Sandpipers and Long-billed Dowitcher. Merlin, Peregrine Falcon, and Northern Harrier occur regularly here, with Peregrines frequently seen chasing shorebirds from the many pannes during late summer. The marsh has a history of attracting rare species including Garganey, Eurasian Wigeon, and Ruff.
The Thomaston flats are susceptible to commercial uses (e.g., clamming and worming, industrial development from adjacent boat yard). It is unlikely the cement factory has any environmental influences on the site, given its long history in the area and the continued abundant bird life at the site. Effort to plug ditches (originally constructed to facilitate draining then harvest of salt hay) was initiated in the late 1990?s. Disturbance is generally not a problem at this site, though occasional rare birds attract large numbers of birders from across New England. An effort is underway to provide improved viewing opportunities from the adjacent uplands.
Weskeag Marsh is fully in conservation ownership, with some of the surrounding upland on the east side protected as well. An easement is being negotiated for further protection near the northern end of the marsh. Access can be found along Buttermilk Lane about 1.5 miles south of U.S. Route 1 in Thomaston. This area is open for public use throughout the year.