The Cariboo Regional District has issued a water quality advisory, to the Horse Lake water users as a result of levels of manganese (Mn) in its drinking water supply. The quality of the drinking water has not changed, but the move is due to changed Canadian guidelines for drinking water. Health Canada established a new maximum acceptable concentration for manganese in drinking water of 0.12 mg/L. Historical water test results show that the wells in Horse lake have produced between 0.14 to 0.29 mg/L of manganese. These manganese levels vary per well and what time of year the tests were taken.