Alexandria could lose a $1 million urban park the Northern Virginia Regional Park Authority is considering creating along the Beltway and the city's southern boundary, if Alexandria insists upon building a road through the parkland.

At its June meeting, before adjourning for the summer, a divided city council approved plans for the road - Eisenhower Avenue - through the proposed park but reduced it from six lanes to two lanes and relocated it along the edge instead of through the middle of the park. City officials say the road changes were a major concession to the park agency, but they have no plans to eliminate the road entirely.

The 45-to-50-acre park site is in the middle of the Cameron Run flood plain, the narrow, four-mile long strip of land along the Beltway where the city is spending $25-$50 million to end flooding and turn several hundred acres into developable land. It is the largest single undeveloped area within the city, and land on both sides of the proposed park is now zoned for industrial and high-rise residential and commerical use.

The park site, which the city has offered to give to the regional park agency if it will construct the park, is the leading-contender for $1 million in urban park funds approved in area bond referendums last year, park officials have said repeatedly.

The site, valued at $2.5-$3 million, was bought by the city for flood control purposes. About 13 acres were purchased specifically for parkland last year for $1.3 million, half of it a federal park grant.

One park authority proposal calls for building five ball fields, leaving 12 acreas in woodland, damming Cameron Run and creating a two-acre lake and building the largest outdoor tennis complex in Northern Virginia, with some 21 courts - comparable in size to the National Park Service's 16th and Kennedy Street complex in the District.

Alexandria has relatively few tennis courts, 50 percent fewer per capita than any other metropolitan area jurisdiction, and the park authority has no tennis courts at any of its large regional parks.

But park authority members are concerned about haveing a road, especially a road carrying industrial truck traffic, through the park they would operate.

In March following a meeting with City Council members, the park authority unanimously urged Alexandria not to make any decision on Eisenhower Avenue before this fall, when the park authority will have finished a study on the need for urban parks in Northern Virginia and where they might go.

Dwight Rettie, one of Arlington's two representatives on the park authority board and chairman of the urban park study committee, said last week "I was most disturbed to hear that the city council voted to approve Eisenhower Avenue in any form. Parks and roads and highways are essentially incompatible neighbors. Sometime it's possible to dampen the effects of a roadway, but roads are hazardous, disruptive and environmental disasters in a park," Rettie said.

His committee was to meet this week, and he said it "is not improbable" that it might recommend the park authority issue an ultimatum to Alexandria to either drop its road plans or forget the $1 million park. Rettie said the Cameron Valley site is the only major urban park site now being considered by the park authority. And despite all the construction and the proximity of the Beltway, railroad and Metro subway tracks, it could be a good one. But Rettie added he was concerned about what is essentially to be a truck route.

City officials last week insisted they have complied with the park authority request to take no action on Eisenhower Avenue since no funds have been voted to actually construct the road. The June vote was take simply to lessen the impact of the road on the park. The previously planned four - or six-lane road was narrowed to two lanes (a 120-foot right-of-way reduced to 60 feet), and it was relocated closer to the Beltway, along the new Cameron Run channel now under construction.

However, city officials also insist the road is essential to the development of Cameron Valley, noting that it was planned three years before they city even considered having a park there. The park proposal came after plans fell through for a $750 million development, proposed by a firm called New America. It would have filled much of the valley with high-rise buildings.

Dayton Cook, director of the city's department of transportation and environmental services, says the plan approved by the city council "reduces the area of impact of the road by two-thirds" and will allow sufficient land for a park. But if they city has to choose between the road and a regional park, Cook clearly is opting for the road and says the city can always develop its own park there.

"In 20 years it won't matter who develops the park; it will look pretty much the same," says Cook. "If we give the land to the park authority . . . and the land is worth $2.3 million . . . there'll be a park there within five years. And if the city has to do it, it will take a lot longer. But then of course it would be for city residents only."

Ellen Pickering, one of three city council members who opposed even a scaled-down Eisenhower Avenue through the park, argues that the proposed four-lane cross roads that also are planned for Cameron Valley will give adequate access to the area - especially when connected with the four-lane sections of Eisenhower Avenue planned for either side of the park.

"Why do we need another road parallel to the eight-lane Beltway and a six-lane Duke Street, all within a few hundred yards of each other?" Pickering asks.

She accuses Cook, Eisenhower Avenue's most ardent proponent, for both insisting on the need for the road and then playing down the amount of traffic it would carry. Even in 1990 the maximum traffic on the two-lane park section is estimated to be 6,800 vehicles a day, about what is experienced on a busy residential street, compared to 15,000 a day along the four-lane sections on either side of the park. However, many of the vehicles will be trucks.

"There's either not going to be enough traffic to justify the road at all, or if there is going to be a lot of traffic, then it's too much to have going through a park," says Pickering. "And we certainly don't want children running around with banks beside a truck route," Pickering says. Eisenhower Avenue, even as a relocated two-lane road, would run directly alongside the area proposed for ball fields.

Mayor Frank Mann, who voted for the road, said this week "We made one hell of a concession to the park authority. We've had public hearings on it, and the planning commission approved it. We voted on it, and as far as I'm concerned, that's that. The issue is dead. . . . The park authority can now do whatever it pleases, but I hope they'll listen to the elected officials" in the cities and counties that make up the park authority. CAPTION: Picture, Construction of Eisenhower Avenue in Alexandria could threaten $1 million in park funds. By Craig Herndon - The Washington Post