The grizzly bears, locomotives and redwood sawmills are long gone.

But remnants of two forgotten ghost towns, submerged 56 years ago when Lexington Reservoir was built near Los Gatos, have resurfaced from its muddy depths.

The reservoir’s water level has been lowered over the past year so construction crews can complete a dam-safety project. The scenic lake along Highway 17 was just 5 percent full Friday, and will remain that low until winter rains begin to fill it again.

As the water level has dropped, brick foundations, fence posts, tree stumps, parts of rock walls, even concrete steps that once were attached to homes and barns in the forgotten 19th century towns of Lexington and Alma have re-emerged along the lake’s western edges.

“This is probably only about the third or fourth time since 1952 that you can see it,” said Bill Wulf, 69, a historian in Santa Clara who roamed the two towns as a boy.

“A lot of history took place there. Lexington was where the first sawmill was in Santa Clara County, in 1847, before the Gold Rush started. All their loggers left for the gold fields and it shut down for a while.”

Also visible now is the road bed from the original Highway 17, an echo from a bygone era.

Dating back to 1858 as a stage coach route and toll road from San Jose to Santa Cruz, the road, which became known as the Santa Cruz Highway, was submerged, like the two towns, under 130 feet of water when the Santa Clara Valley Water Conservation District constructed Lexington Dam in 1952 to meet the water needs of a postwar population boom.

When the reservoir filled, Highway 17 was rerouted to higher ground. But parts of the original route, now called “Old Santa Cruz Highway,” still snake through the woods from Bear Creek Road to the summit area.

Perhaps most dramatic among the reservoir’s newly visible artifacts is a concrete bridge that once spanned Los Gatos Creek between Lexington and Alma. The bridge is stamped with “1926” on both ends, visible to people who park near the Bear Creek Road overpass and walk a few hundred feet down into the dried lake bed.

“This is a view you don’t see too often,” said Dave Chesterman, capital program manager for the water district, as he walked across the 82-year-old bridge in rubber boots.

Chesterman said a $65 million project to rebuild the earthen dam’s outlet system remains on schedule for completion by next September. The project involves carving a half-mile long, 12-foot-high tunnel through St. Joseph’s Hill and installing a steel pipe to replace an outlet pipe system that has crumpled several times due to age and pressure.

As for the towns of Alma and Lexington, their heyday was the mid-1800s, when each of them was populated by about 200 hearty souls. Each town had a post office, hotel, saloons, blacksmith shops and half a dozen redwood sawmills.

Lexington gained national attention in 1883, when a Los Gatos saloon keeper, Lloyd Majors, hired two thugs to rob an elderly Lexington man who kept $20,000 in gold in his cabin. The crooks burned the old man with turpentine-soaked rags and beat him with pistols, killing him and a friend, and then fled with the gold. Their sensational trial in San Jose drew coast-to-coast newspaper coverage similar to that accorded the Lizzie Borden ax murders nine years later in Massachusetts.

Alma’s reputation was more genteel. It became a resort for San Francisco vacationers who hunted for deer or fished for trout. It was surrounded by vineyards and redwoods. The silent movie star Broncho Billy Anderson filmed several Western movies there in 1906.

But both towns were doomed.

Lexington declined in the 1880s, when the South Pacific Coast Railroad — a line that raced passengers, lumber and orchard fruits between Alameda and Santa Cruz in less than four hours — rolled right past the town. Later, the modern Highway 17, finished in 1940, bypassed Alma. By 1950, only about 50 families lived in Alma and less than a dozen families lived in Lexington.

The water district condemned their homes and paid them. Some moved the structures to higher ground. Others relocated.

“The people were welcome to remove the buildings themselves and take the lumber with them if they wanted. Or the district would do it. Whichever worked out best,” said John H. Clarke, 85, of Aptos, who helped build Lexington Reservoir.

“I knew quite a few of them,” said the only surviving water district engineer. ”A lot of them moved to Los Gatos and Saratoga. Most of them have died off now.”

The relocation was unpopular. But the South Bay, with its newly growing electronics companies, was desperate for new dams to help provide drinking water and recharge its underground aquifers.

“A lot of people came here to live from places like Minnesota,” Clarke said. “They liked the warmer weather. But they never brought their own water with them. We had to think of water for the valley. That was what was most important.”

For Wulf the historian, the long-lost towns still hold precious memories. He remembers 1946, when he was 7 years old, riding with his parents and grandmother on a car trip through the mountains. It was raining, and the roof began to leak, so his father stopped at Jimmy Welter’s bar in Alma. As the family sat inside drying off, the young lad noticed his father disappearing behind a curtain in the back.

“I followed him,” he said with a chuckle. “And what was back there? A bunch of one-armed bandits. Gambling machines. A man shooed me out pretty quick.”

Wulf hiked back to see the towns six years later just after construction on the 195-foot-high dam had finished.

“I wanted to see them before they were gone. I could have taken photographs. I didn’t have a camera,” Wulf said.

He found abandoned buildings, including the boarded-up Alma train depot.

“I went in there and it was full of hornets,” he said.

For 56 years, all of it has been lost, under the reservoir, with parts resurfacing only a few times, like during the droughts of 1977 and 1991. And what of the project that has brought fleeting glimpses back to the surface?

“It jogs my mind. It makes me reflect back to when I was a young boy,” said Wulf. “Most people drive along Highway 17 and have no idea what was there. When I go by, I look down and can still picture how those towns looked.”

Contact Paul Rogers at progers@mercurynews.com or (408) 920-5045.