Modesto has agreed to pay the state a $165,000 fine for releasing about 755 million gallons of partially treated waste water into the San Joaquin River in March in violation of its discharge permit.
The city released the waste water to protect one of its treatment plants that had reached capacity. The city's sewer system had been overwhelmed by last winter's heavy rains and from Tuolumne River water pouring into the system after an antiquated section of a major sewer line along the river had collapsed.
Modesto has treatment plants along the Tuolumne and San Joaquin. Waste water is first treated at the Tuolumne plant and then sent to the San Joaquin plant for additional treatment.
City Council members unanimously approved paying the fine at their Tuesday meeting. The Central Valley Regional Water Quality Control Board had proposed the fine after investigating this matter. The water board found that Modesto had 59 violations. It determined that 55 of the violations were subject to what is called a mandatory minimum penalty of $3,000 per violation.
The water board said none of the violations was serious.
City officials have said that the partially treated waste water had 85 percent to 90 percent of its pollutants removed but had not been disinfected so it had bacteria in it.
The waste water that Modesto released is stored and then used to irrigate nearby land planted with animal feed during the growing season. Modesto does treat other waste water to a higher level that is safely and legally released into the river.
It cost Modesto $1.9 million for contractor to fix about 1,100 feet of the sewer line along the Toulumne plus roughly $200,000 for city staff's work. Modesto expects to be reimbursed by the Federal Emergency Management Agency for much of these costs.