ITHACA, NY – On Friday, the City of Ithaca released information summarizing the discolored water situation that included an important new detail: test results showing that concentrations of manganese in the water were higher than the state-mandated limited.
On July 11 the manganese concentration at the water plant was 0.59 milligrams per liter, and on July 19 it was 0.98 milligrams per liter. Both readings are above the maximum concentration limit for New York of 0.3 milligrams per liter, according to the city’s report.
This is classified as a “Tier 3” violation, which is the least serious and requires that the public be notified within 12 months, typically as part of the annual water quality report. (The official notification is here.)
According to the same report , other samples taken on those same days at other locations in the water system all showed concentrations below 0.3 milligrams per liter. This indicates that the concentration that most water users were getting at their taps was lower than what was recorded at the water plant.
More recent samples, taken on Aug. 16, after most reports of brown water had stopped, showed manganese below detectable limits. The city ordered other tests in between, but those most recent ones were expedited. The other results may take time to come in, and may still show elevated levels of manganese.
The city also tested for turbidity, which means cloudiness, of the water. Tests from July showed that turbidity for water in the treatment plant’s holding tanks were above accepted limits. This is a slightly more serious violation, considered “Tier 2”, which requires users of the water be notified within 30 days.
According to the report, turbidity is regulated because it can be associated with bacteria and other microbes. However, the City monitors bacteria levels closely, and none of the 30 tests taken each month by the water department showed any microbial contamination of the water supply.
A study from the National Center for Biotechnology Information does show that excessive manganese exposure can pose health risks, however this is observed in people who have been drinking water with higher concentrations of manganese than seen in Ithaca’s water, and over the course of years.
According to city officials, the city has continued to work on the chemical profile used at the water treatment plant, and they are now reporting that the city’s water is showing normal levels for both manganese and turbidity.
However, they also noted that events such as water main breaks, like what occured last week, can also cause a short resurgence of discolored water.