You may recall from history class that, after gold was found at Sutter’s Mill in early 1848, it took only a couple of years for San Francisco to transform from a sleepy dock town of a few hundred people into a city with more than 20,000 residents.

But this unlikely boomtown sat on a tiny spit of land surrounded by salt water on three sides, and the new denizens of San Francisco couldn't survive on whiskey alone.

There were quite a few freshwater creeks amid the sand dunes of early San Francisco, but nowhere near enough to satisfy the needs of 21,000 people. Clever businessmen made personal fortunes bringing water in from Marin County by barge and then sending horses and donkeys around the city dragging water barrels.

That Marin water was expensive. During dry times, a mere bucket could cost you a gold dollar, which would be worth about $300 today.

"This was a big entrepreneurial opportunity," said Mitch Postel, president of the San Mateo County Historical Association. He said it wasn't long before a handful of speculators started looking to make money by bringing water in from south of the city.

At the time, the Peninsula was sparsely populated with a series of farms and a stagecoach road running through the middle.

"Really, the only outstanding thing that you would have found was the stagecoach stop, which became a pretty elaborate hotel for its day: the Crystal Springs Hotel," Postel said.

A man by the name of George Ensign took in this picture postcard of a scene and realized it could become a vast watershed for San Francisco. Thus began a masterful plan to divert the region's freshwater creeks and put much of this acreage under water.

In 1858, Ensign joined a group of like-minded investors who pushed for a change in state law that allowed for the formation of corporations to supply cities, counties and towns with water. These water companies were empowered to acquire lands and waters by eminent domain.

Two years later, Ensign incorporated the Spring Valley Water Works (later changed to Company), which proceeded to buy up those farms and the hotel in San Mateo County.

"A lot of the times they would enlist the aid of the courts when people got wise to what they were doing, and might have the land condemned at 10 cents on a dollar," Postel said. "They weren’t above any method in order to get the land that they needed."

Today, the watershed has grown to 23,000 acres, a massive protected natural space in an age when much of the San Francisco Bay Area has been paved over for housing, office spaces and freeways.

Despite the enormity of the service provided to San Francisco, the company was hated by its customers. For one thing, there was the ever-present, fetid stench of political corruption and dubious land deals.

"It was a monopoly. It probably had even more latitude in what it could do than PG&E," Postel said.

Also, the water quality and service in San Francisco were said to be awful, and expensive.

As time went on, the greater Bay Area's appetite for water continued to grow with the population, and the reservoirs of the Crystal Springs watershed were not enough. So the Spring Valley Water Company expanded into the Alameda Creek watershed on the other side of the bay, making farmers there angry, too.

Politicians in San Francisco schemed for decades to take the company out of private hands, and they finally succeeded in 1930. That’s when the city started bringing water from Yosemite to the Bay Area, through what is known today as the Hetch Hetchy Regional Water System.

Today, the Crystal Springs reservoirs are part of this water system, but only a small percentage of the drinking water consumed by the Bay Area today comes from San Mateo.

More Crystal Springs Questions Answered

Jackie Nuñez isn't the only person who's asked Bay Curious about Crystal Springs:

"There is a group of private homes on Upper Crystal Springs Reservoir. How was that allowed?" — Rupi Singh

These homes could easily be considered the greatest municipal perk in the Bay Area: residences for the families of watershed keepers and supervisors. The rent is reportedly not market rate, but they’ll tell you somebody’s got to live on the land to watch and protect it from trespassers and the like.

"With all the beautiful open space and hills around the west side of Crystal Springs Reservoir, why isn't the area open to hiking and biking?" — Raoul Wertz

The public can enjoy the Crystal Springs Regional Trail, a 15.3-mile trail, which will eventually run 17.5 miles from San Bruno to Woodside when it’s finished. Currently, the trail serves more than 325,000 visitors annually.