There are two main grassland environments in Lake Clark National Park and Preserve: freshwater grasslands inland and estuarine salt marshes on the coast.

The Lake Clark coast borders Cook Inlet, a large semi-enclosed tidal estuary. Sedge is the dominant growth form in the region's estuarine salt marshes, but grasses and rushes are also present. Estuarine salt marshes are a critical piece of the ecosystem. Detritus such as dead vegetation and spawned-out salmon carcasses are converted to energy and nutrients by the micro- and macroorganisms in the salt marsh environment. They form the bottom rung of the food chain that builds all the way up to large mammals like bears, whales, and humans.

Inland freshwater meadows of grass are expansive. These grasslands are often found as an ecotone - or zone of change - between the lowlying wetlands and coniferous forests located at higher elevations. Freshwater grassy meadows provide habitat for a vast number of birds and mammals.