A clogged dechlorination tablet feeder at the Bonners Ferry sewer lagoon caused a chlorine discharge into the Kootenai River March 23 that dumped more chlorine in one day than the city normally discharges in a week.
On April 16, the city sent a letter to the Kootenai Tribe, whose hatchery is located just downriver from the point of discharge, apologizing for and explaining the mishap.
Chlorine, used to kill algae, is toxic to fish and plants in excess amounts in river ecosystems, and the city uses dechlorination tablets to neutralize the chemical to river discharge before it is released.
The city’s discharge permit allows a maximum discharge allows a weekly maximum average chlorine discharge of 2.8 pounds per day, but the violating discharge released about 4.7 pounds over an estimated eight to 16 hours.
“The City apologizes for the operational issue that caused the release of chlorine into the river, potentially putting fish at risk,” city engineer Mike Klause wrote. “The City puts great value on our relationship with the Tribe and the aquatic life in the Kootenai River. We have taken internal measures to reduce the chances of similar discharge issues from occurring in the future.”