Oakland’s Lake Merritt Swells: Why the ‘Lake’ Flooded and What It Really Is

When you stroll around Lake Merritt on a sunny Oakland afternoon, you expect a serene urban oasis—not ankle‑deep water. Yet earlier this week, portions of the iconic shoreline were literally under water, catching walkers off‑guard and forcing a temporary shutdown of the popular promenade.

“I’ve never seen it like that,” said longtime resident Fuzzy Asfaha, who paused his usual lap around the water. “Usually we take the same route, but we couldn’t get past the water.” He laughed it off, but the scene was striking enough to prompt a quick call to local water‑way specialists.

Adrian Cotter, a volunteer with the Rotary Nature Center Friends, was among the first on the scene. “I heard about the flooding on Thursday and went down to see for myself,” he recalled. As he surveyed the swelling, Cotter reminded everyone that the name “Lake Merritt” is a bit of a misnomer.

“Technically, it’s not a lake at all,” Cotter explained. “It’s a tidal estuary, meaning its water level rises and falls with the ocean’s tides.” The estuary is kept in check by four tide gates that open and close based on the height of the tide measured at the Golden Gate Bridge. When the tide threatens to crest a predetermined level, the gates shut, holding back the Bay’s waters.

So what caused the gates to be overwhelmed this week? Cotter points to a cocktail of distant weather patterns: “I suspect it was storm surge from the tropical storms churning in the Pacific.” Those far‑off systems can push extra water toward the Bay, and if the tide gates happen to be open, the surge sneaks into the estuary and, in turn, onto the surrounding walkways.

The timing couldn’t have been worse for a region that’s already bracing for an El Niño winter. “We get a lot of storms from the Pacific,” Cotter warned. “If a strong storm coincides with a high tide, the surge can cause flooding—just like we saw.” He says the same scenario could repeat later this season, especially if El Niño amplifies storm intensity.

For now, the water has receded, and the paths are reopening, but the brief inundation serves as a reminder: Lake Merritt is as much a tide‑driven estuary as it is a city landmark. Residents and visitors alike might want to keep an eye on tide forecasts and weather alerts, especially as the winter months approach.