In the 1940s, the U.S. government built an aluminum plant beside the Sandy River Delta, then sold it to Reynolds Metal. Waste byproducts (including metals, fluoride, and cyanide) were disposed of on site, some of it into lakes and ponds. Wastewater went into wetlands that drained into a lake, and from there into the Columbia River.

Habitat and agriculture in the area became contaminated by water and air pollution. Once the U.S. Environmental Protection Agency (EPA) declared it a Superfund site, Reynolds Metals worked from 1994 to 2006 to remove toxic waste. The clean-up effort involved temporarily draining the lake to dig out toxins, and installing a groundwater extraction system.

When the US Forest Service purchased land at the Sandy River Delta for restoration, part of the land had belonged to Reynolds Aluminum. The remainder was a cattle ranch, and its marshy sections had been drained for grazing purposes.