Lying unassumingly between its conical neighbors, Mount Shasta and Mount Lassen, the Medicine Lake Volcano is a shield volcano, named after the lake within its caldera. Its periodic eruptions over the eons have created nearly 850 square miles of gently-sloped lava beds, layered on top of one another, making it the Cascade Range’s largest volcano by volume. This unique structure is collectively called the Medicine Lake Highlands, and is the secret behind the region’s critical hydrology. I was there as part of a tour group hosted by Trout Unlimited, Backcountry Hunters and Anglers, and California Trout, in support of a campaign to have the Medicine Lake Highlands designated as a National Monument. The campaign was launched in 2023 by the Pit River Tribe, to whom the Highlands — or Sáttítla, as they call it — is ancestral home, and they’ve been fighting in court to protect the area from geothermal exploitation for decades. TU, BHA, and CalTrout have added their voices to the campaign, recognizing the natural and cultural resources at stake.