Eric Blind sat up to his ankles in mud. With a brush, he scraped away at a structure of 157-year-old brick, taking in a sight he knew would soon disappear.



Behind him, sat the entrance to an old tunnel, carved into the bedrock of San Francisco’s Presidio in the years when mad gold speculation fueled a population explosion in the City.



Just a week ago, this tunnel, with its brick-lined entrance, sat buried beneath 43-feet of earth -- forgotten for a century by just about everyone except for Blind.



“I started going through a lot of old maps,” Blind said, who began searching for the rumored tunnel a dozen years ago. “On a couple of old maps from 1871 they showed these shaft holes and these tunnel openings.”



Last week, crews excavating an old Army landfill in the Presidio came upon the entrance to the old tunnel, dug in 1853. For Blind, it was akin to discovering the Holy Grail.



“It’s become a bit of folklore around here,” he said. “I’ve been talking about it so long without any proof.”



The rumored tunnel wasn’t the kind to conjure images of gold seekers or adventurers. It was a water tunnel, dug by early entrepreneurs hoping to strike it rich by selling San Francisco water from the Presidio’s Mountain Lake.



“It was going to be transformative for the City,” Blind said. “It was one of the things they were doing to kind of compete with Manhattan, which had just got their reservoir system set up.”



The tunnel would carry water underground from the lake, through the Presidio and Pacific Heights, and up to a tank on the top of Telegraph Hill.



An account in the 1853 Alta California described the groundbreaking:



The proposed work of the Mountain Lake Water Company is one of which our city may well be proud,” read the Alta California. “It is yet in its infancy – yet in its cradle. But it was in infancy and in the cradle that Hercules strangled the serpents.



In its own way, the tunnel tells the story of 1853 San Francisco, drunk on gold dust, and beginning to construct infrastructure to carry the ambitions of its biggest dreamers and visionaries.



“This is one example of the kind of infrastructure programs that were going on,” said Presidio archaeologist Kari Jones. “’We’ve got gold, we’ve got a new city. We’re going to build this tunnel.’”



But it appears even some big dreams could only go so far. Workers only dug three-quarters of a mile through bedrock before giving up the following year. No one’s exactly sure why the project went bust. The tunnel, and its shame were eventually covered up.



Blind stood in the mud near the mouth of the tunnel, snapping pictures and taking a last look. Old wood beams lined the entrance, below a wall of old brick. The entrance was filled in with years of sediment.



The next day, just a week after its discovery, excavation crews re-buried the tunnel. Blind hopes to unearth it again in the spring, and eventually preserve it as a monument to a different sort of San Francisco history.



“This is an effort where someone was trying,” Blind said. “A huge endeavor to bring water to the growing city of San Francisco right after the gold rush. It failed gloriously.”