Water from 10 saline wetlands in Saskatchewan was provided as drinking water for 1-day-old mallards (Anas platyrhynchos). Ducklings given water with conductivity from 3,750 to 7,490 microns hos/cm grew as well as birds on fresh water during a 14-day trial, but birds given water with conductivity of 4,000 microns hos/cm grew poorly during the last 2 wk of a 28-day trial. Ducklings given water with conductivity of 7,720 micron hos/cm grew poorly during a 14-day trial. Six of 10 ducklings given water with conductivity of 20,000 microns hos/cm died, and only two of nine ducklings given water with conductivity of 21,500 microns hos/cm survived 14 days. Survivors were much smaller than controls and had many abnormalities. All ducklings given water with conductivity of 35,000 and 67,000 microns hos/cm died within 60 and 30 hr, respectively. The results indicate that ducklings hatched on many saline wetlands will suffer toxic effects unless they are able to find a source of fresh water shortly after hatching.