The Stringfellow Acid Pits are a toxic waste dump and Superfund site located in Jurupa Valley, California, United States, just north of the neighborhood of Glen Avon.

Situated at the base of the Jurupa Mountains in Pyrite Canyon, the 17-acre (69,000 m2) site was originally a rock quarry owned by James Stringfellow.

In 1956, after a year long negotiations, and at the request of the Santa Ana Regional Water Quality Control Board (RWQCB),[1] Stringfellow opened the site for dumping toxic waste.

[3] Stringfellow claimed his company was without assets, and title to the land passed to the State of California, with oversight given to the Santa Ana River Water Quality Board.

Between 1969 and 1980, poor weather and management resulted in several spills and intentional releases of toxic chemicals into Pyrite Creek, which flowed into storm channels running through Glen Avon.