Racial discrimination and polarization persist at the polls in many of Maryland's southern and Eastern Shore counties, according to a state elections audit released today, but only in Somerset County do they appear to be severe enough to violate the federal Voting Rights Act.

The 111-page audit of 11 heavily black counties, issued by the office of Attorney General Stephen H. Sachs, said Dorchester County also is in likely violation of the federal law. But the issue has become moot there with a recent federal court settlement in which Dorchester agreed to institute a district-by-district voting system.

Although it found only Somerset with discrimination patterns severe enough to violate the Voting Rights Act, the audit said exclusion of blacks from the electoral process is widespread. Between 1962 and 1982, for example, according to the study, a total of 282 commissioners and county council members were elected in the 11 counties, but only one was black. The counties' voting-age populations are on the average about 21 percent black.

There is a "special sense of isolation among members of the black community," the audit said, "a sense that they are governed, but do not participate in governing, and that important public issues are decided for them, not by them."

The year-long audit urged amending the state constitution to permit all counties to abolish at-large elections -- a system the audit says tends to dilute the black vote.

Also, the audit recommended repeal of so-called dual registration legislation that in many counties requires voters to register separately for municipal and county elections.

At-large elections "significantly inhibit the opportunity of black citizens to participate fully in the enterprise of county government," the audit said. "We also believe that the practice of dual registration . . . is a confusing and burdensome impediment to the exercise of the franchise by voters of both races."

The audit was ordered by Sachs last year to determine if any of the state's major jurisdictions violated the Voting Rights Act. Under recent amendments, the act said a violation existed if, based on the "totality of circumstances," the electoral process was "not equally open" to blacks and whites.

Sachs originally selected 13 of the state's 23 counties that have at-large elections and a black population of 10 percent or more -- most of them Eastern Shore and southern counties and many with a history of racial discord.

Howard and Anne Arundel counties were studied but were found in November not to be in violation of the Voting Rights Act. Both counties subsequently voted to switch to a district-by-district electoral system.

Of the remaining 11 counties, only three -- Dorchester, Somerset and Wicomico -- had concentrations of blacks sufficient to create predominately black voting districts, the audit said. The study found that despite some racial polarization in Wicomico County, the "statistical evidence is overshadowed by the demonstrated effectiveness of the black community in mobilizing support for its candidates, even under the at-large system."

In all the others -- Calvert, Caroline, Charles, Kent, Queen Anne's, St. Mary's, Talbot and Worcester -- the black population was so evenly dispersed that the at-large voting system could not blamed for any alleged discrimination.

In Somerset County, no black has ever won an at-large office, the audit said. "The 'totality of circumstances' shows an economically depressed black citizenry, largely estranged from the processes of decision-making . . . whose candidates must face the barrier of at-large voting by an electorate that is, to a considerable extent, racially polarized," the audit said. County officials declined to comment on the audit.

At the other end of the gamut was St. Mary's County, where a black was elected sheriff in 1978, the audit said, and "the black community has been actively involved in the political process and bears less of the lingering effects of racial discrimination."