The Lake Sammamish watershed receives nearly twice the rainfall of downtown Seattle, precipitation that once filtered through old-growth forest before reaching the lake. Today, that runoff courses over parking lots and lawns, carrying sediment and pollutants that cloud the waters and threaten the fish below. Kokanee salmon, a landlocked variety that once thrived here, now teeter on the edge of local extinction. The federal government has asked surrounding cities to restrict shoreline development, a request that has met resistance from communities built on growth.

In recent years, North American beavers have returned to Lake Sammamish, building dams on tributary creeks and creating the ponds that once sustained this watershed. City officials worry about flooding and blocked salmon runs, calling for the animals' relocation. Yet research from the nearby Stillaguamish River tells a different story: watersheds that lost their beaver ponds saw coho salmon production drop by 89 percent. The debate over these industrious rodents mirrors the larger tension between development and ecology that defines this lake.

Marymoor Park anchors the lake's northern shore, while Lake Sammamish State Park occupies the south. On summer weekends, the lake fills with waterskiers, wakeboarders, and fishing boats pursuing bass, trout, and the occasional salmon. But the state park carries darker memories. On July 14, 1974, a warm Sunday afternoon, a man with his arm in a sling approached young women on the beach, asking for help loading his sailboat. Two women who agreed to help were never seen alive again. The man was Ted Bundy, and Lake Sammamish became one of the most infamous crime scenes of the twentieth century.