"Oh, I've never seen it like that. This is like, flooding all over," said Oakland resident Fuzzy Asfaha.
The flooding stopped him from using his usual walk around the lake.
"Usually we take the same route, but we cannot pass it," Asfaha said. "Yesterday was special. I don't know what it is."
To understand what caused the flooding, we turned to local experts familiar with the waterway.
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Adrian Cotter with Rotary Nature Center Friends said he heard the lake was flooding on Thursday and went to see what was going on.
"I came down to the lake and saw it had definitely flooded," Cotter said.
Cotter said the first thing people should know is the name 'Lake Merritt' is misleading. "Lake Merritt is not technically a real lake," he said.
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Instead, it is a tidal estuary, meaning water levels rise and fall with ocean tides.
Cotter said the flow of water is controlled by four tide gates.
"They monitor the tide at the Golden Gate and when it gets to a certain height, or when they know it's going to get to a certain height. They'll close the gates," he said.
Cotter believes the unusually high water was linked to weather conditions far from Oakland.
"I suspect it was storm surge from the tropical storms that are churning out in the Pacific," he said.
According to Cotter, the storms pushed additional water into the estuary through tide gates that were likely open, causing water to spill onto surrounding walkways.
He said similar flooding could occur again this winter if storms coincide with high tides during the El Nino weather patter.
"We get lots of storms coming in from the Pacific. We can get more storm surges. If those are at times with high tides, those that can cause flooding," Cotter said.