Agency:.Produced by the National Film Board of Canada for the Fisheries and Marine Service of Environment Canada.

Director, Giles Walker ; editing, Giles Walker ; producer, Desmond Dew ; executive producer, Colin Low ; commentary, Stanley Jackson ; photography, Don Virgo ; sound, Ken Page ; sound editing, Victor Merrill ; re-recording, Jean-Pierre Joutel ; music, Eldon Rathburn.

Narrator, Stanley Jackson.

Recorded 1974.

What are the processes that can change a clean, balanced freshwater environment into a sick one? This film describes a variety of projects undertaken by scientists at Environment Canada's Freshwater Institute in Winnipeg. They are seeking the answer to this important question, and finding ways to restore and protect our freshwater world. This is a film of discovery: the vulnerability of our freshwater world, the damage we have already done it, and how we can help restore and protect it.

Mode of access: World Wide Web.

Description based on online resource; title from title screen (National Film Board of Canada, viewed 2023-08-10).