Calvin Larson, a Reston homeowner, has been around long enough to remember a time when he could sail across 17-year-old Lake Anne without a care.

No more.

"You can practically stand up in the middle," says Larson, who long ago tired of running aground in Lake Anne in his sailboat. "I don't sail much anymore."

The calm surface of those Reston lake waters hides a turbid truth that Larson and other Restonians are struggling to come to terms with: Lake Anne, the gemstone of this planned community, is fast becoming a marsh. Silt, accumulating at the rate of two inches a year, already has filled in the shallow coves and now is threatening the life of the lake itself.

For a town that treasures its natural setting--indeed, Reston was designed specifically to highlight that setting--the deterioration of Lake Anne is an ominous sign, and not just because of the potential impact on the lake's beauty. It is going to cost tens of thousands of dollars to revive the lake, and Reston homeowners--all dues-paying members of the Reston Homeowners Association (RHOA), which maintains the community's pools, tennis courts and open space--are going to have to pick up the bill.

Already, the association has committed itself to spending $75,000 to do some dredging of Lake Anne in the spring. But that expenditure will completely drain the association's dredging fund. The prospects for the future are not promising, either. Reston has three newer lakes--Thoreau, Audubon and Newport--which eventually will need dredging, too.

RHOA's maintainance manager for open space now concedes that RHOA is looking into the possibility that an ongoing dredging program for all the lakes eventually will be needed.

The rescue and preservation efforts are complicated by the fact that the three newer lakes are owned by The Reston Land Corp., the planned community's developer, which is considering turning ownership of them over to the homeowners association ahead of schedule.

Some Restonians contend that the proposal is a tactic designed to shift potential liability for the dams built to create the lakes to homeowners, who argue that the dams may be unsafe. Such a shift could cost RHOA tens of thousands of dollars if the dams were ever to burst or cause injury to residents downstream, they claim.

Some "of the dams don't have emergency spillways, and there is evidence that the Lake Thoreau dam leaks," says Charles Baker, a resident who is spearheading an effort to get Reston's developers to upgrade the dams before turning them over to RHOA ownership sometime in the next few years.

But recent engineering studies of the dams, done at the developers' expense, show that the dams at lakes Audubon and Thoreau are safe. The chances of dam failure and flooding are very small, according to the studies.

Skeptical Reston residents remain unconvinced, however. They have asked the Fairfax County government's engineering consultants to review the studies and report their conclusions to the county supervisors. Nonetheless, Reston Land president Francis Steinbauer has refused to promise that the developer will fix all problems identified in the studies before turning the dams over to RHOA.

"We're going to be in Reston for the next 15 years," Steinbauer says. "It's not in our interest to give RHOA a dam with lots of problems. Our dams, we think, are healthy and we want to prove that."

RHOA president Judi Ushio says RHOA will not accept ownership if there are any "real problems" with the dams. RHOA has scheduled a public forum on the dams for Feb. 11, and may take up the issue of whether to accept ownership of the lakes at a Feb. 24 meeting of the RHOA board.

For the 1,000 or so Restonians who own lakefront property, the benefits of having lakes may very well outweigh the costs of maintaining them. But there are 21,800 families in Reston whose enjoyment of the lakes is limited to a walk on Lake Anne plaza or a momentary view from the car window as they drive to the grocery, thanks to restrictions that generally give control of access to those with lakeside property.

Not surprisingly, those not living beside a lake are far from happy at the prospect of seeing their RHOA dues go toward paying for dredging or dam repair when they cannot fully use the lakes in question.

Faced with budget constraints last fall, RHOA considered charging lake-dwellers an extra $20 a year, on top of the $131 annual membership fees. The proposal was dropped after it created such an outcry it threatened to delay the association's budget process. But Ushio says it may be brought up again next year.

"The problem is that it would establish classes here," says Harry Mustakos, president of the independent Reston Community Association. "The next thing they would do is go after those who live next to the golf course, or closest to the pools."

But others contend that there already are classes in Reston, and the elite are those 1,000 homeowners with lake privileges. Although pedalboats and canoes can be rented on two of the lakes and a few privately owned boats were allowed on Lake Audubon last summer, there is growing resentment over the policy of limited access. Ushio says RHOA will set up a committee this month to look into ways the lakes can be shared by all Reston families.

How lake-dwellers will respond is uncertain. Most paid around $25,000 extra for their homes to get lake privileges, and may not give them up without a fight. Homeowners on Lake Anne maintain they don't kick people off their lake, that anyone can fish from any of the dams, and that no one is supposed to swim in the lakes anyway. But they are also protected by the deed for their lake, which stipulates that access will remain limited to homeowners.

"These aren't good sailing lakes," says Larson. "You barely get going and you're on the other side. By the time someone buys a trailer and a trailer hitch they're going to drive over to the Potomac."