The snake's in the springhouse and all's right in Hillsboro.

Some things about the town of Hillsboro are lost in antiquity: what year the town was incorporated, why the town's name was changed from The Gap to Hillsboro, and when the blacksnake first took up residence in the springhouse.

But he is there again this year and his return is of enough moment that water commissioner Sandy Muir saw fit to announce it at the last Town Council meeting. What's more, council members and residents greeted the news with delight.

The five-foot blacksnake, or one very much like him, has lived in the stone springhouse on Short Hill mountain for as long as officials and former officials of the Loudoun County town can remember. He is welcome, they say, because his nature compels him to eat mice and other rodents, large bugs and even, some believe, other less-welcome snakes. This helps keep the town's only source of water, the spring, pure and clean, residents believe.

Last week two former mayors and a Town Council member sat in front of a crackling fire, sipping wine, munching fresh popcorn, talking about their snake.

"Everybody was glad to hear that he's back," said former mayor Hobart Rowe, now a sculptor. "He'd been missing for a while and Sandy has been worried about it. We all were."

"Our water is clean," said Byron Farwell, former mayor and military historian. Farwell said the blacksnake deserves a bit of credit for that.

"He polices it [the spring house]," said former mayor Evelyn Turbeville. "No other kind of snake does that."

Having a blacksnake does cause a bit of concern for water commissioner Muir when town business takes him into the springhouse. Although blacksnakes are neither poisonous nor aggressive, they have been known to bite if frightened. "He [Muir] takes a flashlight and a cane every time he goes up there," said Rowe, "and he waves the cane around a lot before he goes in."

According to Dale Marcellini, chief herpetologist at the National Zoo in Washington, little is known about blacksnakes in the wild. "All we know for sure," he said, "is that they're nice snakes and people kill them because they think they're copperheads. People think everything is a copperhead."

Marcellini says that because blacksnake babies are patterned and gray instead of the adult solid dull black (shiny black immediately after shedding), the young are most often mistaken for so-called bad snakes. The correct name for the snake is black rat snake, he said, although most people shorten it to blacksnake.

According to council member Ruth Farwell, a teacher in Purcellville, most of the town's 125 residents have a blacksnake in their attics and are quite used to them.

Said former mayor Evelyn Turbeville: "I came home the other day and a six-foot blacksnake had climbed down the chimney and was lying across the hearth." She got rid of it, she said, by shouting, "What are you doing here? Get the hell out."

But nobody says that to the town snake. For $34 a year, Hillsboro residents get all the water they can use and a five-foot guard to help keep it drinkable. A bargain, officials say.