Duluth Reservoir Discharge Killed 2,300 Fish in 2024

A routine reservoir maintenance project in July 2024 resulted in the accidental destruction of thousands of brook trout.

Updated on Oct. 2, 2026 in Aquariums

Gouache-painted editorial illustration of a rocky creek bed and drainage pipe with fish silhouettes, representing a local environmental maintenance incident. — Duluth utility crews discharged chlorinated water into Tischer Creek in July 2024, killing over 2,300 fish including thousands of brook trout. AI Illustration. Upload story photo >

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In July 2024, Duluth city crews drained 1.7 million gallons of treated drinking water into Tischer Creek during a reservoir inspection. The discharge contained chloramine levels that killed approximately 2,300 fish, including 1,588 brook trout.

Why it matters

The incident highlights the environmental risks posed by aging utility infrastructure during routine maintenance. Following the event, the city implemented new protocols to route drained water into the sanitary sewer system rather than stormwater drains.

The 110-year-old Woodland Reservoir released water at a rate of 10.7 cubic feet per second into a stream system flowing through 2 miles of habitat. The discharged water contained 1.6 parts per million of chloramine.

The players

City of Duluth

The local municipality managed the reservoir maintenance that led to the accidental chemical discharge.

The details

Utility crews performed a routine sanitization and inspection of the reservoir, opening a valve that connected directly to the local stormwater sewer system. The massive volume of treated water overwhelmed Tischer Creek, which had a flow rate of only 0.19 cubic feet per second during the event.

The reservoir release occurred over 15 hours in July 2024.
A water main break affected Coffee Creek in the fall of 2025.

Culture Shift

This incident follows a documented trend of municipalities struggling to reconcile century-old infrastructure with modern environmental regulations. It marks a departure from historic maintenance practices, forcing cities to prioritize ecological preservation over traditional drainage methods.

Residents may see changes in how utility work is conducted in their neighborhoods to prevent further contamination of local creeks. The brook trout population is expected to take at least eight years to recover from the impact of the 2024 incident.

The takeaway

The city paid $12,000 in civil penalties and $190,000 in natural resource compensation following the incident. These costs underscore the significant financial consequences for municipalities that fail to contain treated water during maintenance operations.