Tests have concluded that about 200 cattle found dead in a pasture in southwestern Saskatchewan drank toxic water.
Dr. Betty Althouse, the province's chief veterinary officer, says water samples from the pasture's dugout had a sulphate concentration of more than 24,000 milligrams per litre.
Sulphate concentrations over 1,000 milligrams per litre can cause neurological trauma in cattle and can kill at levels over 7,000 milligrams.
Dissolved solids, including salts, in the water were also extremely high at 33,400 milligrams per litre. Information from the provincial government suggests water with dissolved solids greater than 7,000 milligrams should not be used for cattle at all.
Althouse didn't provide details Thursday as to what other dissolved solids were in the water.
She said the cause seems to have been a lack of rain and evaporation due to hot weather.
"The evaporation plays a big role in that and it just concentrates what's there," Althouse said .
The dead cows and calves were discovered last Friday on Crown land south of the community of Chaplin. The pasture is operated by a grazing company and leased by 33 cattle owners.
At the time, much of southwestern Saskatchewan was under a heat warning as temperatures hovered around 30 C.
Althouse said there can be few signs for several days when animals drink that much salt in water.
"They may look fine for a few days and then there would be sudden deaths. It's not like you're going to see a few die one day and a few the next. It does tend to be a fairly sudden catastrophic event," she explained.
"That would make it very challenging to pick up or prevent in many ways, because I don't think any of us were really as prepared for the level of quality problems that there are in this water."
RCMP and animal protective services are investigating.
An estimated 240 surviving cow-calf pairs were moved to a different pasture that has a safe and secure water source, although a handful have since died and others remain under veterinary care, Althouse said.
The Agriculture Ministry is getting increasing reports of poor water quality from people across the province, particularly in the southwest. People may have to bring in other water sources, set up water tanks or troughs, Althouse suggested.
"The water quality seems to be worse than many had suspected."