The water quality of most of San Diego County's 11 watersheds rates no higher than fair in a report released today by San Diego Coastkeeper, an environmental group.
One of them - the Tijuana River Valley watershed - is rated poor.
Only the San Dieguito watershed in the North County receives a score of good. No watersheds are rated excellent.
San Diego Coastkeeper based its ratings on water testing for pH levels, dissolved oxygen, metals, two forms of nitrogen, phosphorous and two types of fecal matter.
In seven watersheds - Carlsbad, Los Penasquitos, Otay, Pueblo, San Diego, San Luis Rey and Sweetwater - the water quality exceeded regulatory thresholds for two or more of the indicators.
The Tijuana River Valley watershed has the worst rating in the county.
According to Coastkeeper, it exceeded United Nations Environment Program standards in all indicators but metals and had the highest concentrations of ammonia, nitrates, phosphorous and bacteria among all the watersheds rated.
Coastkeeper and the Surfrider Foundation monitor three locations in the Tijuana River Valley when water is flowing, according to the report.
They found unhealthy levels of oxygen, high amounts of electrical conductivity (indicating the presence of an excessive amount of detergent or salt), high concentrations of ammonia, nitrates and phosphates and large amounts of fecal matter.
According to Coastkeeper, fecal matter bacteria like E coli and enterococcus exceeded regulatory standards 89 percent to 94 percent of the time in the Tijuana River Valley during the 2010-11 monitoring season.
Bacteria concentrations were higher during the rainy season, the report said. About 70 percent of the watershed is in Mexico.
