District to begin monthly mercury monitoring after industrial discharges trigger ultra-low limits

At a regular meeting, board members directed staff to increase mercury monitoring at the district discharge point to monthly sampling and reporting after difficulty complying with extremely low local limits set by the City of Elkhart, staff said.

Dan, a district staff member, told the board the district has been sampling and recently moved to monthly testing under a consent agreement. He reported recent test results as "less than 0.00001," and said the district had previously been conducting quarterly sampling but will now supply monthly reports to the industrial customer and to Elkhart as required.

Board members said the low limits adopted by Elkhart — described in discussion as being on the order of parts per trillion — have made compliance challenging for the district's largest customer (referred to in the transcript as Anto/Antoan). Staff urged the board to confirm the laboratory method and its lowest detection limit; a board member asked Dan to email the method and detection threshold so the board can verify it is "meaningful." Dan said the district conducts the sampling internally and that the city and the industrial customer also conduct their own sampling at their discharge points.

Members discussed the technical process for setting local limits and noted those limits are partly calculated from assumptions about residential and industrial contributions; staff said the district plans to review those assumptions in-house at the next permit-renewal cycle. The board agreed to revisit whether to return to quarterly testing after about six months of consistently passing results.

The board also discussed the downstream regulatory context: staff said the city of Elkhart's permit and treatment processes remove a large share of mercury before discharge to the St. Joseph River, and that any future change in the city's local limit could affect the district. A member said the incremental cost of the monthly testing was modest (staff estimated approximately $50 per month for the additional test), and that the district would seek to work with the industrial customer and the city to avoid unnecessary expenses.

Next steps: staff will provide documentation of the laboratory method and detection limits, begin monthly sampling and reporting, and schedule a follow-up discussion after approximately six months of monitoring results.