EDGEWATER, MD. -- Former senator Charles McC. Mathias was back in the limelight last week, accepting the applause and gratitude of nearly 70 people who gathered near the water south of here in Anne Arundel County to dedicate a new environmental laboratory in his name.

Mathias, a leading advocate of efforts to clean up the Chesapeake Bay during his tenure in the Senate, broke ground for the lab, which will be an extension of the Smithsonian Institution's Environmental Research Center.

"It is of course only fitting to name the new building after the man who for decades has been a leader in protecting the great natural resources of the Chesapeake Bay," Dean Anderson, undersecretary of the Smithsonian Institution, said during the ceremony. "Mac Mathias has consistently promoted a series of wide-ranging activities designed to understand, manage and protect the bay."

Mathias, who was senator for Maryland from 1969 until his retirement this year, sponsored an effort by the EPA to conduct research on the bay and its surrounding area in 1975. The report concluded that toxins and an excess of harmful nutrients, such as nitrogen and phosphorus, were causing a slow decay of the estuary, a finding that helped spark the massive state and national cleanup.

The Smithsonian complex, officials said, investigates the bay's watershed and the disruption caused in the bay by human activity. The center is one of the largest facilities in the nation studying the impact of human communities -- with their wastewater, farming, construction and development -- on waterlife, according to Smithsonian officials.

The Charles McC. Mathias Jr. laboratory, a 7,400-square-foot, $943,000 complex of offices and labs shaped like a horseshoe, is expected to be completed by fall of 1988.

Construction of the lab will increase the center's space by one third, and 7 new staff researchers will be added to the current 50.

Mathias spoke with pride about the new laboratory, and he praised the Smithsonian's efforts to acquire "original research and useful basic knowledge. I have great hope for it {the lab}. I feel somewhat embarrassed to have it be associated with me at least in name but aside from embarrassment, a great deal of pleasure and pride," he said.

Sen. Paul Sarbanes (D-Md.) offered his congratulations to Mathias and the members of the institution in a letter read by his aide Bridgette Smith. "At a time when the Chesapeake Bay was reaching a crisis stage in its environmental decline, Senator Mathias took the lead on this issue and made it his personal crusade. Mac Mathias has been the catalyst which lead ultimately to the current program reversing the decline of the Chesapeake Bay."