Penn Mine Disaster and Massive Fish Die-off

Walking Waterhoods: Lodi Lake

Penn Mine Disaster and Massive Fish Die-off

Lodi, California 95240, United States

Created By: Wholly H2O

Information

Fish kills (or fish die-offs) are signs of serious environmental distress in rivers and other bodies of water. Common reasons for fish kills are human sewage and agricultural fertilizers causing algae blooms and deoxygenating the water. Another common cause is contamination from mining in upper watersheds.

For the Mokelumne River, toxic sulfuric acids left in the soil from the Penn Mine killed off fish and aquatic life several times over the decades, effectively sterilizing the river for a year or two. The Penn Mine operated primarily as a copper and zinc mine between 1859 and 1953. Miners used acids to leech the metals out of ore and kept these acids in ponds, which also caused acid build-up in the soil. During years of intense rain, the runoff would make it to the river, polluting the water and killing fish and other aquatic life.

Though this was a regular phenomenon after 1953, it took decades for different enforcement agencies and public interest groups to win in court to clean up the mine site. There were many attempts at reducing runoff starting in the 1970s, but it wasn’t until around 2000 that East Bay Municipal Utility District (EBMUD) paid $10M to remove 360,000 cubic yards of contaminated dirt. Sadly, this type of residiual and active contamination is a common problem in rivers all over North America, as is the need to repeatedly take legal measures to force clean ups.

This point of interest is part of the tour: Walking Waterhoods: Lodi Lake


 

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