The long-awaited Crystal Springs Dam Bridge opened on Friday, offering hiking, cycling and auto access along one of the most scenic stretches of the San Francisco Peninsula.

“It’s just beautiful. They did a great job,” said cyclist Gary Stanton of San Mateo. “I never thought I’d say this, but it’s worth the wait.”

The new $13.1 million bridge, eight years in the making, spans the top of the dam between the two artificial lakes of Crystal Springs Reservoir. The dam was recently raised and the width of the spillway doubled so the reservoir can hold and release more water.

Under sodden skies, crowds flocked to Friday’s opening ceremony, serenaded by a soft chorus of tree frogs. Some gazed north towards one lake, fed by San Mateo and San Andreas creeks. Others looked south into a gorge. The two lakes, connected by a culvert, help store drinking water for millions of Bay Area residents.

The bridge connects with the newly opened South Sawyer Camp Trail, which extends more than a mile south of the bridge along the pristine 130-year-old reservoir. A pair of bald eagles built a nest in a Douglas fir tree in the northwest of the lower reservoir, the first time the raptors have nested in San Mateo County since 1915.

“The old road didn’t have separation for bikes and foot traffic. Now you can stop and take a look at the reservoir. It’s user-friendly,” said Kent Pearce, who watched its construction over the years.

The new bridge – 51 feet by 626 feet in size – was expected to be completed soon after the dam renovation was completed in 2016. The bridge was closed on Oct. 21, 2010, construction of the new span started in February 2016 and finished last October. The project led to a years-long closure of a section of Highway 35, also known as Skyline Boulevard, north of State Route 92.

“The Hoover Dam was completed in less time. It’s great to see the Crystal Springs Dam and Sawyer Camp extension happening today but the project is years over schedule,” said Andy Howse of Open the SF Watershed, a volunteer group attempting to get the San Francisco Public Utilities Commission to allow hiking access to the trails of the watershed, now off-limits.

But building the bridge was no easy feat, said project engineer Carter Choi. Before the bridge could be demolished a colony of endangered red-legged frogs had to be caught in a pond atop the old dam and moved deeper into the watershed, where they’d be safe.

A special three-foot-high fence was erected along the entire perimeter of the project so that the frogs and two other rare species, the San Francisco garter snake and dusky-footed woodrat, wouldn’t wander onto the construction site.

“The frogs made it through the project,” said Pearce, happily.

“The garter snakes, too. Don’t forget the garter snakes!” said friend Mike Pagano, under an umbrella. “This is really good news.”

With water on one side of the project and a sheer 300-foot dropoff on the other, construction equipment couldn’t be stored on either side. Work was started in the middle, then spread outward.

“Space was tight,” said Choi. “Getting equipment in was a challenge.”

Moreover, because the reservoir holds drinking water, construction had to be very tidy.

High-voltage PG&E transmission lines, previously supported by towers, were relocated underneath the bridge so they wouldn’t be visible.

Because the dam and bridge were higher than the old structure, the approaching roadway had to be raised as well, then paved. The project also required coordination of several agencies.

Before it was covered by water, the region was the campsite of the Portolà expedition of 1769. Now it is a longstanding favorite place for commuters and athletes who use its roads and trails. Originally built in the 1880s by a private company called the Spring Valley Water Company, the reservoir now belongs to the city of San Francisco. Some of its water comes from rain and the rest is piped in from the Hetch Hetchy Reservoir in Yosemite National Park, as well as the Pilarcitos Creek watershed and Alameda Creek watershed.

“We live in the fifth largest economy in the world, but sometimes people don’t realize that so much open space is available,” said David Canepa, a member of the San Mateo County board of supervisors.

“This place where people can hike and bike and get away from the city,” he said, “creates such opportunity and hope.”