“…it has been determined there were no violations of the disinfection byproduct maximum contaminant level (MCL) or corresponding threat to public health during or after the ACH trial.”
-State Water Resources Control Board, Division of Drinking Water
ABC 10’s November 3 report on City of Sacramento drinking water quality misrepresents critical facts about the City’s water treatment and water quality sampling process in 2013-14, and falsely asserts that the City supplied drinking water that did not meet safe drinking water standards. The delivery of water meeting all health and safety standards is an absolute priority for the City.
The information below is provided to correct the false and incomplete assertions in the ABC 10 report.
Also see State Water Resources Control Board’s statement about the ABC 10 news story.
Background
Part of the process for treating water before it is distributed as drinking water includes the addition of a chemical coagulant that binds with impurities in the water so that these impurities settle out and are removed from the water. The City of Sacramento historically has used Aluminum Sulfate (Alum) as a coagulant in its drinking water treatment process.
Beginning in May 2013 through April 2014, the City tested the use of a different chemical, Aluminum Chlorohydrate (ACH), as a coagulant in its water treatment plant on the Sacramento River. The effectiveness of ACH was documented in research, and other agencies in the area were successfully using ACH as a coagulant in their water treatment process. The purpose of the City’s ACH test was to evaluate treatment results during the test period so the City could determine whether ACH provided a treatment method that was equal or superior to the use of Alum at a reduced cost to City ratepayers. After approximately 11 months, the City determined that ACH was not as effective as Alum and resumed using Alum as a coagulant in its Sacramento River water treatment plant.
The use of ACH during this test period complied with all water quality standards and did not in any way compromise public health or the safety of the drinking water supplied to City residents.
ABC 10’s report states that while the City was testing the use of ACH as a coagulant in its water treatment plant, the City supplied drinking water with disinfectant byproduct (DBP) levels that were unsafe and put customers at risk. The report asserts that these DBP levels exceeded Environmental Protection Agency (EPA) maximum contaminant levels (MCLs). (The MCLs set a regulatory limit on the amount of DBPs allowed within the water distribution system.)
These assertions are false. The City at all times complied with water quality standards and reporting requirements and at no time did the City provide a water supply that was unsafe or that put City customers at risk. The delivery of drinking water that meets all health and safety standards is an absolute priority for the City.
To ensure those standards are met, the City takes water samples from various designated sampling sites on a quarterly basis to determine DBP levels within the City’s water distribution system. For each monitoring site, the last four quarterly results for DBPs are averaged to calculate a Locational Running Annual Average (LRAA), which is the regulatory measurement for compliance with the DBP MCL. If the LRAA for any site exceeds the MCL set by EPA, the City would be in violation of the MCL and would be required to report the exceedance and take steps to reduce the LRAA below the MCL. This never occurred during the period of time while the use of ACH was being tested, and has not occurred at any time before or since.
More detailed information on disinfection byproducts and the water quality standards that apply to them is provided on the City Utilities Department website.
ABC 10’s report states that City staff misrepresented to the City Council that the State mandated a one-year trial period for the ACH.
This assertion is false. The City did not say that the State required the City to use ACH instead of Alum as a coagulant at the City’s water treatment plant. The City elected to test the use of ACH, instead of Alum, to determine if ACH provided a safe and effective treatment method at a reduced cost to City ratepayers. After the State had approved the City’s initial request for a shorter trial period, the City requested that the test period be extended to one year to allow ACH’s effectiveness to be evaluated under different seasonal conditions within a year. The State approved this extended trial period as a condition to the City’s future application for a water system permit amendment that would allow the City to permanently shift to using ACH, if merited by the evaluation results. This is what the City staff report’s reference to a State mandate referred to.
ABC 10’s report suggests that during one of the quarterly tests, in January 2014, the Sacramento Plant where the ACH use was being tested had been shut down to manipulate the City’s DBP sampling results.
This assertion is false. The City has two surface water treatment plants, and routinely shuts down one or the other of its plants for maintenance during the winter period of low water demand. The Sacramento Plant was shut down from December 23, 2013 to February 25, 2014 for this purpose, and for the performance of work associated with the City’s ongoing treatment plant rehabilitation project that could not be performed while the plant was in operation. This shut down had nothing to do with the City’s ACH testing or the City’s water quality sampling.
The EPA’s DBP regulations require water sampling at 12 designated sites at quarterly (90 day) intervals. The City has no option to sample at alternate sites or different times. The January 2014 water quality sampling was conducted at the other 11 sampling sites, but sampling at the Sacramento Plant was not conducted because the plant was shut down and no drinking water was being produced.
ABC 10’s report states that prior to another quarterly sampling, the City obtained water service from the Sacramento County Water Agency to manipulate the City’s DBP sampling results.
This assertion is false. In December, 2014, well after the City had concluded the ACH test period and had switched back to the use of Alum as a coagulant at its water treatment plant, the City initiated an operational evaluation to identify a long-term strategy to reduce DBP levels in a portion of the City’s water distribution system where the City’s quarterly water sample in April 2014 had indicated an elevated DBP level. Water quality deterioration can typically be mitigated by flushing the distribution lines, however during a drought this is not an option.
Rather than risk reduction in water quality and possibly exceeding regulatory requirements, City staff identified a short-term option for reducing the DBP level, by obtaining a temporary addition of water from Sacramento County via an existing interconnection. The City asked for State approval to do this, and after receiving State approval the City obtained water from Sacramento County during January through March 2015. The addition of this water into the distribution system was successful in lowering the DBP level. The City did this to maintain water quality and comply with regulatory requirements, not to manipulate sampling results.
As explained above, the City’s drinking water did not exceed the EPA’s regulatory limit for DBP levels in the water distribution system during the period of time while the use of ACH was being tested, nor has this occurred at any time before or since.