Mountain Lake Park's Best Story Isn't the Alligator Anymore

Ask anyone who has lived in the Inner Richmond long enough and they will eventually bring up the alligator. In August 1996, a retired architect and birdwatcher named Dan Bushnell spotted something moving in the murky water at Mountain Lake, at the southern edge of the Presidio. Ten weeks, two rival newspapers, a boys' choir performance of "Puff the Magic Dragon," and one $1.47 fishing lure later, San Francisco Zoo curator John Aikin pulled a three-foot alligator out of the lake on a Tuesday night in October. The Examiner ran a naming contest. "Golden Gator" beat out "Van Nessie" and "Darth Gator." By December he was on a plane to New Orleans.

It is a good story, and it gets told because it is funny and true. But it belongs to an era of the park that residents walking the loop today would barely recognize. The alligator wasn't a fluke. He was one entry in a longer list of things people dumped into Mountain Lake because nobody was watching closely enough to stop them: goldfish, carp, bullfrogs, crawdads, a whooper swan named Myrtle who used to stop traffic on Lake Street and steal snacks from the Lake Market at 12th and Lake. For most of the twentieth century, the lake was less a habitat than a container.

That container has spent the last decade being emptied out and refilled, on purpose, one species at a time. If you already treat Mountain Lake Park as a fixture of your week, the parcourse loop, the dog run, the bench by the water, the more interesting version of the alligator story is the one still happening. It just moves slower and doesn't come with a mascot.

The Park You Already Know

Mountain Lake Park sits on a narrow band of land bordered by the Presidio to the north and Lake Street to the south, and most of what makes it useful hasn't changed in decades. The fitness circuit that loops the park's perimeter, most commonly entered from 9th Avenue, was installed in 1973 by Peter Stocker, a golf industry figure and Bay Area real estate developer credited with bringing the first parcourse to the United States. The tennis courts at the 11th Avenue entrance run on a first-come, first-served basis, same as every other public court in the city outside Golden Gate Park. The playground sits at the end of 12th Avenue, and the dog play area, one of the oldest and largest off-leash runs in San Francisco, occupies the park's northeast corner, drawing regulars from both the Richmond District and Presidio Heights.

None of that infrastructure is new, and none of it needed to be. The volunteer group Friends of Mountain Lake Park has stewarded the grounds since 1980, keeping the parcourse maintained and organizing the annual Party in the Park. What has changed is what's in the water at the center of it all.

What the Lake Used to Hold

Mountain Lake used to be bigger and cleaner than it is today. It was already shrinking by 1897, when its water was diverted to irrigate the new Presidio golf course, and it shrank further in 1939, when fill from the MacArthur Tunnel cut was dumped nearby to build the Funston Avenue approach to the Golden Gate Bridge. Runoff from that roadway, later Highway 1, carried decades of pesticide residue and leaded gasoline emissions straight into the lake. On top of the pollution came the pets: aquarium fish and reptiles released by people who no longer wanted them, none of which belonged in a San Francisco lake, all of which pushed out whatever native life remained.

By the time Jonathan Young, a biologist who has studied the lake's sediment core samples going back 2,000 years, began working with the Presidio Trust to reverse the damage, the goal was not nostalgia. As Young put it to the San Francisco Examiner, the aim was never to recreate the lake exactly as it once was, but to get it functioning again:

"the goal is to restore it in a way that allows it to remain healthy and functional."

That distinction matters. Nobody was trying to turn Mountain Lake into a museum piece. They were trying to make it work again as a lake.

The Reversal, Species by Species

The restoration didn't happen all at once, and the sequence tells you something about how deliberate it was. In 2013 and 2014, the Presidio Trust removed contaminated soil and invasive species from the lakebed. Water quality improved enough that by April 2015, ecologists reintroduced the first native species: 153 three-spined stickleback, harvested from Lobos Creek elsewhere in the Presidio, some of which had already laid eggs by the time they were counted. Within the following month, Pacific chorus frogs went in. Later that same year came Western pond turtles and California floater mussels, a filter-feeding freshwater mussel that once helped keep the lake's water clear before it disappeared along with everything else.

Here is the full list of what came back, and the order it happened in:

1. 2013 to 2014 — Contaminated soil and invasive species removed from the lakebed
2. April 2015 — Three-spined stickleback reintroduced, sourced from Lobos Creek
3. Spring 2015 — Pacific chorus frogs reintroduced
4. Later in 2015 — Western pond turtles and California floater mussels reintroduced
5. Ongoing — San Francisco forktail damselfly reestablished as part of the same effort

The proof that it worked showed up six years later. In 2021, a wild-hatched baby Western pond turtle was discovered at the lake, the first confirmation that the reintroduced turtles were not just surviving but breeding on their own. That is a different kind of milestone than catching an alligator. Nobody wrote a song about it. But it is the actual measure of whether thirty years of work paid off, and it did.

What Shows Up on a Walk This September

The Presidio's own description of Mountain Lake calls it a stop on a migratory superhighway running from Alaska to South America, with roughly 65 bird species passing through over the course of a year. September puts you in the middle of the fall leg of that route, and the sightings logged at the park back that up. Recent entries on the park's public iNaturalist checklist show a mix of residents and passing migrants documented within the past two months:

None of that is guesswork. It's what people walking the same loop you walk have actually logged, with dates attached, in real time. The Western pond turtles that were reintroduced in 2015 still bask along the south shore near the playground, and the Pacific chorus frogs that arrived that same spring were logged as recently as March 2025. If you bring binoculars on your next lap, you're not hoping to spot something rare. You're checking in on a project that's been running for over a decade and is still producing results.

There's a smaller, quieter marker of the whole effort near the south shore: a pet amnesty drop box, installed by the Presidio Trust in 2015, where aquatic pets can be surrendered instead of released. It exists because of what happened to the last generation of animals someone decided they didn't want. The alligator got a newspaper contest. Today's unwanted goldfish just get a box.

Worth the Detour

The Golden Gator story is the one that travels, because it's funny and self-contained and doesn't ask anything of you. The restoration story asks a little more. It asks you to notice that the turtle sunning itself near the playground didn't wander in from nowhere, that the frog chorus you hear at dusk is the result of a specific decision made in a specific spring, that the same water once written off as a dumping ground now supports a self-sustaining population scientists are still tracking. Mountain Lake Park hasn't changed its footprint in decades. What's living in it has changed almost completely, and it happened close enough to home that you could have watched it happen from the parcourse.

Amanda Jones Advisory writes about the Inner Richmond the way we work in it: paying attention to the details that make a place what it actually is, not just what it looks like from the outside. If you're thinking about buying or selling in this neighborhood and want that same level of attention applied to your own next move, Amanda Jones Advisory is glad to help. Book a private consultation whenever you're ready to talk.