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Santa Margarita River Water Quality Information

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Water quality in the Santa Margarita River, whose head waters lie in the eastern portion of Riverside County and runs, unimpeded, for 27 miles from Temecula to the Pacific Ocean, has been impacted by human induced activities. Water quality parameters that have been identified as highly concentrated or potentially problematic (Constituents of Concern) along the mainstem and tributaries of the river have been identified and listed in the Environmental Protection Agency’s 303(d) List of impaired and threatened waters. Every other year (on even numbered years), states are required to identify all waters where the required pollution control methods are not effectively or sufficiently attaining or maintaining the desired water quality standards. Total Maximum Daily Loads (TMDLs) are then developed and implemented for impaired water bodies based on the severity of the pollution and the beneficial uses (how the water can be used) of the waterbody.  

The waterbodies in the Santa Margarita River watershed that have been identified on the 303(d) list include: De Luz Creek (iron, manganese), Long Canyon Creek (Total Dissolved Solids[TDS]), Murrieta Creek (iron, manganese, nitrogen, phosphorus), Rainbow Creek (iron, sulfates, TDS, nutrients), Sandia Creek (iron, manganese, nitrogen, sulfates, TDS), Santa Margarita Lagoon (eutrophic), the upper Santa Margarita River (phosphorus), and Temecula Creek (nitrogen, phosphorus, TDS). Sources of the water pollution include agriculture, livestock, domestic animals, urban runoff, and septic systems. High concentrations of these water quality parameters in water with multiple beneficial uses, such as people touching, fishing or playing in it, can be detrimental not only to the health of the habitat, plants and animals, but also to the people who work and play in the water.

For information on how homes and business can improve water quality through simple, every day efforts visit Living in a Healthy Watershed.

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Between 2002 and 2005, the District conducted a citizen water quality monitoring program, called the Home2Ocean Program, which sampled water quality in Rainbow Creek, Stone Creek (another tributary of the Santa Margarita River) and the mainstem of the Santa Margarita River. Water samples were taken on a bi-monthly schedule and the Final Data Report was completed at the end of the program.


Santa Margarita River Water Quality Resources