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EPA Report Slams California: San Joaquin and Merced Rivers Contaminated

Over Half of State Water Resources Contaminated or at Risk in New Report, Fail to Meet New Standards
It has been alleged that Merced groundwater is contaminated with a compound known as MTBE, a gasoline additive, which may potentially be carcinogenic.
Photo by Saema Adeeb

The reported number of polluted California waters has increased tremendously, and now includes the San Joaquin River, according to a report released last week by the US Environmental Protection Agency (EPA).

Since 2006, the number of rivers, streams, and lakes in California that do not meet federal standards of quality jumped 170 percent, making the latest number of polluted California waters the highest to ever be documented. According to the EPA, 1.6 million of the 3 million acres of the state’s waters are either “not meeting water quality goals or are in need of a pollution plan.”

In accordance with the federal Clean Water Act, state officials monitor and evaluate water quality then report their findings to the EPA. In 2010, the State Water Resources Control Board compiled and submitted its report, which included the list of the state’s waters that were found to be of lower quality.

The EPA rejected the submitted list of impaired waters as incomplete. The finalized list, released by the EPA on October 11, adds 24 more water body names, including the lower Merced River and portions of the San Joaquin River.

Officials partly attribute the increase in the number of reported polluted waters to more comprehensive monitoring, rather than a new flood of contamination. The list of impaired waters finalized by the EPA was compiled by 22,000 data submissions by cities, counties, and water quality control boards all over the state, a significant increase of data compared to the 2006 report.

Regardless of whether the numbers result from better data collection or increased pollution, officials are calling the report a “wake-up call” for California. Trash in waters and mercury in fish increased 76 percent and 24 percent from 2006 levels respectively. Reported unsafe bacteria levels have jumped 90 percent. Pesticides, bacteria, and minerals are the most common pollutants found.

The water bodies the EPA added to California’s 2010 list of impaired waters include portions of the Merced, San Joaquin, Tuolumne, and Stanislaus rivers. Pollutants identified in these specific rivers have raised temperatures and increased the electrical conductivity of the water. The segment of the San Joaquin River that starts from the Merced River and ends at the Tuolumne River, for example, was found to be “warmer and saltier" compared to past years' findings

Particular portions of the San Joaquin River that are contaminated to the greatest extent are those downstream of Fresno and those that flow toward Merced. Increased temperature and salinity in these waters pose dangers for trout and salmon populations, and increase health risks associated with fish consumption.

Federal law requires that the state develop Total Maximum Daily Load values, or the maximum amount of a pollutant a water body can receive to meet quality standards. According to the EPA, state officials still need to set TMDLs for 1.4 million acres of California water.

Officials say that the new list of impaired waters provides a new lead for the state in putting together a successful cleanup plan. The full list and pollution measurements can be found on the EPA website.