Baltimore Mayor William Donald Schaefer, eager to repair his image with environmentalists, tromped through tall grasses along Anne Arundel county's South River here today to inspect an erosion control program.

He said the county-sponsored aquatic nursery was the type of experimental effort needed to help clean up the Chesapeake Bay and that its implementation could speed up the effect of the critical areas development curbs, guidelines passed this year that environmentalists have heralded as necessary to clean up the bay. Schaefer encountered a storm of protest a month ago when he suggested those guidelines might be lifted in two years.

Meanwhile, Schaefer's Democratic primary opponent in the race for Maryland governor, state Attorney General Stephen H. Sachs, also was campaigning on environmental issues. He was cruising along another part of the shoreline in Calvert County, at the University of Maryland's Center for Environmental and Estuarine Studies. While there, he attacked Schaefer for remarks the mayor made in sympathy with local support for building another bridge to span the bay.

Schaefer has been trying to erase the impression that he favors business over environmental concerns since his statement on the critical areas limits. Within days of making it, he rescinded it, saying he meant perhaps 50 years, not two.

Schaefer has since said that ways should be found to implement the bay guidelines more rapidly.

Rules and regulations designed to protect the state's shoreline, Schaefer said today, "oughtn't to be concreted in" so that there is no room left for modifications brought about by new technology.

Today, Anne Arundel County Executive James Lighthizer and Stephen Ailstock, an assistant professor of plant sciences at Anne Arundel County Community College, showed Schaefer the pilot project funded by the state and the county in which the county has begun to grow seagrasses along a sandy shoreline. The grasses eventually will be transplanted in the river or on the bay floor as a way of slowing erosion. Schaefer said he would support a similar state program.

The environmental issues have provided a forum for Schaefer and Sachs to exchange barbs for weeks.

Schaefer recently traveled to Massachusetts to study the state's bottle recycling law and is still deciding whether to support a similar program in Maryland, a measure that the Baltimore city administration has opposed in Annapolis in past years. Sachs has already said he opposes such legislation.

Schaefer took further jabs at Sachs today, saying that he has no hands-on experience dealing with the problems of the environment.

On his own tour, Sachs said that although Schaefer did not go as far as endorsing the proposal for a new bridge over the Chesapeake in southern Maryland, his comments had shown "once again that Mayor Schaefer does not understand Maryland and he doesn't understand the environment." A new bridge, Sachs said, would be "too expensive and environmentally dangerous."

Said Sachs, "The mayor's never met a construction project he didn't like."