Head of Tide Park marks the upper tidal reach of the Cathance River.

The Cathance is one of six rivers – along with the Kennebec, Androscoggin, Muddy, Abagadasset, and Eastern – which drain 38% of the state of Maine and converge to form Merrymeeting Bay.

Cathance River, one of six rivers that flow into Merrymeeting Bay, the only body of water in Maine used by all twelve of the Gulf of Maine diadromous species.. The Lower Kennebec River and Merrymeeting Bay together comprise the Kennebec Estuary, one of Maine’s most significant natural areas. The Kennebec Estuary is the second largest estuary on the East coast, containing 20 percent of Maine’s tidal marshes

The Bay is one of only four places in the world where large rivers, with entirely separate watersheds come together to form an inland, freshwater, tidal delta.

The 15-foot waterfall you see before you separates the tidal from the freshwater portions of the river. Below the falls you see Freshwater Tidal Marsh. Merrymeeting Bay and its source rivers are associated with some of the most extensive Freshwater Tidal Marshes in Maine.

Plant species commonly found in this unique habitat include:

Softstem bulrush (Schoenoplectus tabernaemontani)

Sweetflag (Acorus americanus

Yellow water-lily (Nuphar variegata)

Pickerelweed (Pontedaria cordata)

Wild rice (Zizania palustris) – an important food source for migratory waterfowl and other birds such as bobolinks.

Because freshwater tidal marshes are so uncommon, they are home to rare plant species. Eight rare species are frequently found in Merrymeeting Bay and the lower Cathance River, including:
  • Beaked spikerush (Eleocharis rostellata)
  • Eaton’s bur-marigold (Bidens eatonii)

    Eaton’s bur-marigold (Bidens eatonii)

  • Long’s bitter-cress (Cardamine longii)
  • Parker’s pipewort (Eriocaulon parkeri)
  • Pygmyweed (Crassula aquatica)
  • Spongy arrowhead (Sagittaria calycina)
  • Stiff arrowhead (Sagittaria rigida)
  • Water pimpernel (Samolus valerandi)

Perhaps the most notable inhabitant of this stretch of river is the globally rare Eaton’s bur marigold (Bidens eatonii). More than a thousand individuals of this rare plant live along a 300-meter section of the Cathance riverbank.

Due in large part to the extensive areas of wild rice and excellent fish spawning and nursery habitat, the tidal freshwater marshes of the Cathance and Merrymeeting Bay support thousands of ducks, geese, rails, wading birds, and other water-dependent species during spring and fall migrations.

Over 50 species of freshwater fish and ten species of anadromous fish use Merrymeeting Bay and the rivers that feed into it, including:

Rare Atlantic salmon (Salmo salar)

Critically endangered Atlantic sturgeon (Acipenser oxyrinchus)

Critically endangered shortnosed sturgeon (Acipenser brevirostrum)

Recreationally important striped bass (Morone saxatilis)

Alewife (Alosa pseudoharengus), considered essential for the restoration of Gulf of Maine commercial fisheries

Other anadromous species include: rainbow smelt, blueback herring, American shad, tomcod, sea-run brook trout and sea lamprey.

Larger predator species like eagles, herons, and osprey are also drawn to this area.

Heron with Alewife, Howard Cederlund