San Dieguito Watershed tests ‘better than most’

By Claire Harln

Staff Writer

As part of the largest volunteer-based water quality monitoring program in the state, Coastkeeper tested waters recently and their results for the San Dieguito Watershed show local oceans are in relatively good condition compared to other areas of San Diego. The San Dieguito Watershed includes Del Mar and stretches north to Solana Beach and east to State Route 79.

“The watershed shows some problems typical of urbanization, such as slightly elevated concentrations of some nutrients,” said Coastkeeper spokeswoman Nicole Lee. “This is typical of irrigation of agricultural land or overwatering of lawns.”

The local sites tested are downstream from agricultural land and gold courses, which could be the reason for the elevation in nutrients, she said. However, she said, these levels are only slightly elevated, she said, and “mostly do not exceed the standards set in the San Diego region basin plan.”

One particularly noteworthy data point was in on the Del Dios Highway next to the fruit stand, she said. There, low levels of dissolved oxygen were recorded. The dissolved oxygen levels were 4.60 mg/L, and the basin plan standard is at least 5.0 mg/l.

“This low level of oxygen in the water will stress aquatic organisms,” Lee said.

According to Project Clean Water, an organization set up by the various storm water departments and other regulatory agencies, the San Dieguito River watershed is a drainage area of approximately 346 square miles in west-central San Diego County, including portions of the cities of Del Mar, Escondido, Poway, San Diego and Solana Beach.

“This rapid urbanization and development of the open space will cause more water quality problems if low impact development practices are not used. We will see some of the same problems as the Los Peñasquitos watershed has seen due to the rapid growth of the Carmel Valley area.” Lee said.

But in regard to recent testing in the San Dieguito Watershed: “In comparison to other watersheds in San Diego, I would say it is in good health,” Lee said.