Known for its biotic diversity, this small wilderness was declared a permanent natural preserve in 1993 with support from the EHHA, thus protecting it from any future development.

Club members and their families enjoy swimming, sunbathing, picnicking, and fishing in Lower Emerald Lake during the summer months.

Squatters began occupying the Argüello rancho amid rumors that the family's title to the ranch was no good.

By the mid-1850s, legislator Horace Hawes had a big parcel between Whipple and Woodside roads, with a house on the site of Sequoia High School.

The name Emerald Hills was first used in a 1920 brochure distributed by George Irvine, who had big plans but inadequate cash .

When he lost the property near the lake, it was purchased by Charles Holt, the Anglo-California Bank employee assigned to the foreclosure.

The developers aimed their marketing at San Francisco families, emphasizing the proximity of Emerald Lake Hills as a weekend or vacation retreat and especially singing the praises of its largely fog-free climate.

They cited the "climate best by government test" and compared it to "the eternal summer which Lord Byron ascribed to Greece."

A Leonard & Holt newsletter says the area "rivals the beauty of fine old European towns," and predicts it will become a resort famous throughout California.

One of the early members of the Country Club was famous San Francisco attorney Vince Hallinan, who led the campaign against a swim dress code, citing the chic European women he'd seen in modern swimwear.

By summer 1927 they had built the lake by damming a creek and had created a beach, water slide, diving platforms and a playground with "equipment of the most novel design."

In 1929, the Easter Bowl, an outdoor amphitheater, was built at the crest of California Way, and a large concrete cross above it at the high point of the development.

Tony Gardenier related to the Tum Sudens along with the other family owners who had deep ties attempted to keep this cross lighted nightly, but the city council found it too expensive.

The upper lake and an adjacent area of 17 acres (69,000 m2) were sold in 1938 to Simpson Reinhard, a prominent jewelry store owner.

Within a few years of the end of World War II, Emerald Hills was making the transition from a vacation resort to a residential area, albeit a rustic one.

The Emerald Lake Homeowners Association was established in the 1950s to contest the planned routing of an interstate highway through the neighborhood.

(Completed in the early 1970s, Interstate 280 runs west of Emerald Hills, sticking close to the San Andreas Fault.)

Also near the lake was a convent occupied by Franciscan sisters from 1967–70; the order then built a large compound, Mount Alverno, adjacent to the Elks golf course.

A survey of homeowners at this time showed that, having staved off the interstate threat, they were most concerned with keeping the neighborhood's rustic nature.

On the whole, they opposed annexation to Redwood City, and supported bigger lot sizes for a maximum of 1,400 homes in the area, more trails, and preservation of the lakes and two unique features, the Easter Cross and Handley's Rock.

At the time, a large parcel adjacent to the proposed freeway at the community's northern edge was being considered for a possible Cal State campus.

That plan was abandoned, and, because the presence of a little butterfly called the bay checkerspot helped lead to the defeat of attempts to build a golf course there, the land is now Edgewood County Park.

Emerald Hills used septic tanks until the early 1980s, a factor that limited building: In 1982, the year the sewer system was installed, the neighborhood had 900 homes.

Among the new residents were several players of the San Francisco 49ers, including Joe Montana, as the team was then training in nearby Redwood City.

Children may also attend schools with specialized focus, like North Star Academy (academics), or Adelante (Spanish immersion).