In the shallow waters of the Bay, underwater grasses sway in the aquatic breeze of the current. Also called submerged aquatic vegetation or SAV, these amazing plants provide food and habitat for waterfowl, fish, shellfish and crabs.

Microscopic zooplankton feed on decaying grasses and, in turn, become food for larger animals. Minnows dart between the plants and graze on tiny organisms that grow on the leaves and stems. Small fish seek refuge from larger, hungrier mouths.

Shedding blue crabs conceal themselves in the vegetation until their new shells have hardened.

In the fall and winter, migrating waterfowl search the sediment for nutritious seeds, roots and tubers.

Bay grasses are one the most important resources of the Chesapeake Bay. Their presence or absence is an indicator of the health of a river or creek. There are 14 common species of Bay grasses found in the Chesapeake Bay and tributaries.

Bay grasses once formed immense underwater meadows, covering up to 200,000 acres in the Chesapeake Bay and its tributaries. With increasing development and nutrient pollution in the late 1960s and early 1970s, and Tropical Storm Agnes in 1972, the huge grass beds began to decline.

Factors that affect water clarity, also have an impact on the growth and survival of SAV. Suspended sediments and other solids cloud the water, reducing the amount of sunlight reaching the plants. Often, sediment covers the plants completely. Sources of suspended sediment include runoff from farms, building sites and road construction. Shoreline erosion also adds sediment to the Bay.

Excess nutrients promote algae blooms that cloud the water, reducing the sunlight that plants need to grow. Some algae species grow directly on the plants.

Major sources of nutrients include sewage treatment plants, agricultural fields and fertilized lawns.

SAV continued to disappear, hitting an all-time low of about 38,000 acres in 1984. Efforts to restore the water quality in the Chesapeake Bay watershed have had a positive effect on the grasses. In 2002, SAV distribution was estimated at 89,659 acres.

To help restore Bay grasses, citizens can join the Grasses for Masses program coordinated by the Chesapeake Bay Foundation. The CBF provides equipment and conducts workshops to train volunteers to grow Bay grasses at home, school or the office. Participants receive a simple aquaculture system, seeds or cuttings and curriculum materials. They then grow the grasses for about two months, during which time they monitor water quality and measure growth before planting the grasses in a designated restoration sites.

Volunteers are growing wild celery (Vallisneria americana), redhead grass (Potamogeton perfoliatus), water stargrass (Heteranthera dubia), sago pondweed (Stuckenia pectinatus) and eelgrass (Zostera marina). The workshops begin in the winter. Planting mainly takes place in May and June.

For information about this program contact Jill Bieri at Students and teachers who would like to help restore underwater grasses should call 888-728-3229 and ask for the restoration coordinator.

Here are other actions that citizens in the watershed can take to improve conditions for Bay grasses:

  • Reduce the amount of fertilizer applied on a lawn.
  • Replace some lawn grass with native vegetation suited to local soil, light and moisture conditions.
  • Those who use a septic system, should make sure it is properly maintained.
  • Use a compost pile instead of a garbage disposal.
  • Divert runoff from paved surfaces to vegetated areas.
  • Plant strips of native vegetation along shorelines or streams to reduce erosion.
  • Avoid boating in shallow areas and Bay grass beds.
  • Pump boat waste to an onshore facility.

To help identify Bay grasses, download the Guide to Underwater Grasses from or check out the Maryland Department of Natural Resources On-Line Key at