San Dieguito River Park

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Treatment Ponds

(Leer en Español)

When restoring the Lagoon area of the park, it was realized that a high volume of urban runoff from surrounding areas would let out directly into the lagoon. As a way to naturally filter pollutants and minimize the amount of freshwater entering the saltwater marsh habitat, a series of four natural freshwater marsh treatment ponds were created. The method of treatment was to create a series of linked ponds using a natural swale through which the runoff would flow, leaving in the ponds the sediment, pesticides, invasive progagules, nutrients, bacteria and chemicals.

The Park has partnered with San Diego Coastkeeper to conduct monthly water quality testing to gauge the ponds’ effectiveness. If you would like to volunteer please visit our website at

Letter A represents where the urban runoff enters into the treatment pond one. It is then diverted under a constructed berm by a culvert to direct flow into treatment ponds two, three and four. It is then filtered through four treatment pond before being released into the salt water marsh (letter B).




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