More questions about MSD’s power outage and damage to water quality

On March 6, 2023, the Metropolitan Sewer District’s newly installed transformer failed catastrophically and all power to the treatment plant was lost for about three days. MSD had no power backup system, although the separate standby system was supposed to protect critical processes of the treatment plant. Generators had to be brought in from out of state to restore some of the power and activated sludge brought in from other MSD plants to restart the biological treatment of sewage at the plant.

Hundreds of millions of gallons of untreated sewage was discharged to Mill Creek and the Ohio River. This dry weather discharge is of greater pollution strength than usual overflows since it was not diluted by rainfail as is the case with most Combined Sewer Overflows. The discharges were visible, odorous and immediately showed very high levels of e.coli. Mill Creek Alliance assisted MSD by conducting monitoring in Mill Creek. You can see some of Mill Creek Alliance’s data so far at
as of this writing, recreation on Mill Creek should be avoided due to this public health hazard.

This transformer replacement project was the result of a 2014 study that identified issues with the electrical system and the standby power system. The project was estimated at about $3 million initially and funded by Hamilton County for planning and design in 2015 and construction in 2019, where the price had risen to nearly $11 million. By 2020, the price had risen to $18.5 million.

  • Many questions remain about this outage.
    The extent of the damage to species in the Mill Creek and on the Ohio River and when these water bodies will fully recover is unknown.
  • We still do not know the root cause of the transformer failure.
  • The reason for cost escalation and delay in the installation of the new transformers is not known. (only one of the two had even arrived at the treatment plant).
  • The plant is still at risk of losing power since it is operating with one transformer (one of the old transformers was reinstalled). The second transformer would have provided some level of backup (previously there were two transformers where the second would operate if one failed.)
  • But additionally, the standby power system also approved for upgrades has not been implemented.
  • What steps will be taken to be sure that the replacement of both transformers doesn’t result in failure?

Cost increases, lengthy delays, and potential risk to public health and the environment remain big concerns for Mill Creek and the Ohio River.

Mill Creek at CSO 005 after the loss of power at the Mill Creek Waste Water Treatment Plant. This section of Mill Creek showed the highest bacteria counts after the start of the spill.

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