October 26, 2022 A bird flies over remnants of a tidal marsh that has been trapped for decades as a manmade salt evaporation pond. (Paul Kuroda / For The Times) By Rosanna Xia Good morning, and welcome to the Essential California newsletter. It’s Wednesday, Oct. 26. I’m Rosanna Xia, an environment reporter specializing in stories about our coast and ocean. You can usually catch me geeking out about intertidal ecology or some delightfully obscure critter, and gosh do I have a story to share with you today. For years, I would fly into San Francisco and wonder about the massive ponds of magenta and lime green water that sprawl for miles along the southern edges of the bay. The shocking hues of pinks, reds and greens are quite a sight to behold, but the story behind them surprised me even more. [Read today’s subscriber exclusive: “Building with nature: Can reviving a marsh save this California town from sea level rise?”] Turns out these ponds are salt mining ponds, and they used to all be coastal wetlands — a swath of tidal marsh larger than Manhattan. Early California settlers, capitalizing on native Ohlone salt-gathering practices, had diked thousands of acres of wetlands into big, shallow ponds that could then be controlled by pumps and tidal gates. The view we see from the plane today is a vivid display of how the shoreline became one of the largest salt evaporation complexes in the world. For more than two decades, a head-spinning number of government agencies have tried to turn these salt ponds back into salt marsh. It’s the largest coastal wetland restoration west of the Mississippi and a mega example of building with nature, rather than against it, in the face of climate change. If done right, this project could ultimately save a long-neglected community and also reframe the way California adapts to sea level rise. A salt marsh harvest mouse. (Paul Duginski / Los Angeles Times) Reviving the forgotten marshy edges of the bay could also revive endangered wildlife such as the salt marsh harvest mouse, which exists nowhere else in the world. (Salt marshes on the West Coast, by the way, are also at risk of disappearing entirely as an ecosystem in less than a century.) There are so many layers to this story, and I’m excited to hear your thoughts. My email is rosanna.xia@latimes.com, and you can find me on Twitter. Thank you for reading, and I hope you enjoy learning about these salt ponds as much as I enjoyed piecing together the history.