Christopher Swain, who swam the entire 1,243-mile length of the Columbia River, returns to Astoria next month for a local showing of a film that chronicles his journey.

“Source to Sea: The Columbia River Swim” will be shown 7 p.m. Aug. 2 at the Columbian Theater, 1102 Marine Drive. The event is sponsored by RiverVision and Columbia Riverkeeper, which will host a reception for Swain at 5:30 p.m. at RiverVision’s office at 433 13th St. in Astoria.

“Source to Sea” is a collaborative project by more than 30 Northwest filmmakers who chronicled Swain’s year-long solo swim down the river from its headwaters in British Columbia to the Pacific Ocean.

Swain, a former Iron Man triathlete, conceived of the swim as a way to bring attention to pollution and other threats to the Columbia. Along the way he encountered icy-cold waters and waves, as well as sewage and industrial contaminants. He also met with an estimated 13,000 people along the way, including thousands of schoolchildren with whom he shared his vision for a clean, free-flowing river.