San Dieguito Freshwater Runoff
Treatment Ponds



The San Dieguito River Park's Freshwater Runoff Treatment Ponds are 5 acres located east of I-5, south of the Albertson's Shopping Center on Via de la Valle. The purpose of this project was to treat the urban runoff coming from a 313 acre watershed above the Albertson's Shopping Center before it entered the newly created tidal wetlands of the San Dieguito Wetland Restoration Project. 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. In addition, the ponds would reduce the amount of freshwater that would flow into the tidal wetlands.

Before and After Photos

The considerable runoff that entered the site created very wet conditions and a great deal of vegetation. However, the vegetation was generally invasive plants that do not benefit the native ecosystem.

The pictures below show the existing conditions when work began.

The first thing the contractor had to do was clear and grub the site. The pictures below show that operation.

Once the site was cleared, the next step was rough grading.

The photo below shows the orange fencing that marks the limit of disturbance. On the other side is the environmentally sensitive area that is outside the construction area. The black fence is a silt fence, which is intended to keep sediment out of the river.

The photos above shows the survey stakes that mark exactly where the grading should be done, so that the elevations match the project design. Below is the grading plan,click for enlargement.

Above: The high water table was a constant problem during construction.




Above: Now the shape of the ponds begin to show.

Initially we believed that the dirt would balance out - that is, that excavated soil from the ponds would be used to create the berms and that no soil would be imported or exported, but in fact, about 2000 cubic yards had to be imported.


Above and below: One of the project features was to create a weir (hardened, lowered section) in the berm where water can flow over the top of the berm in storm situations. The Treatment Ponds are not intended for flood control purposes. They are intended to function properly handling routine urban runoff.







Below: the grading of the ponds, berms and trail is complete.









Below: This project was funded with $550,017 from the State Water Resources Control Board.

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