Over the course of two and a half decades, the Sohappy family lived and fished along the banks of the Columbia River and encountered mounting opposition from federal and state officials. During that time, Washington State officials confiscated approximately 230 fishing nets from Sohappy. The family also had to fight a federal move to evict them from their home. Nonetheless, Sohappy was persistent in his convictions and continued to live and fish as his forebears and his religion dictated. In an interview with Michal Conford and Michele Zaccheo for the documentary River People--Behind the Case of David Sohappy, Myra Sohappy declared: "The white man says I'm breaking his laws. But what about my laws? The laws we got, unwritten laws--our laws come from the Creator. That's the way you gotta live. Is it a crime to try to survive and eat in this country?"

In 1983, as a result of "Salmonscam," an undercover operation by the federal government, Sohappy and his son, David, Jr., were arrested and convicted of selling more than 300 fish out of season. They were sent to Geiger Federal Prison in Spokane, Washington, to serve a five-year sentence. The Yakima Tribal Council, Democratic senators Brock Adams of Washington and Daniel Inouye of Hawaii, and Sohappy's lawyer, Thomas Keefe, Jr., protested that the sentence was ridiculously severe. This chorus of voices, combined with the news that Sohappy's health was failing, led to his release on May 17, 1988, after serving about 20 months of the sentence. Sohappy then returned to Cook's Landing to live with his wife and family. During his incarceration, he had suffered a series of strokes and endured transfers to prisons in three other states.