In Canada, winter temperatures, regardless of pH, are low enough to keep the formation of un-ionized ammonia below the toxic threshold. Potentially toxic conditions typically start in May and can continue through to early October, depending on the water system and the yearly variation in pH, dissolved oxygen and temperature. Ammonia is generally not problematic with respect to the eutrophication of fresh waters in Canada, as this is typically limited by phosphorus. There are a few exceptions to this, in particular the Qu Appelle Lakes in Saskatchewan. Ammonia released by the Regina WWTP, coupled with phosphorus mobilization from sediments, seems to be contributing to the continued eutrophication of this lake system.
Conifer trees are sensitive to ammonia exposure from air, particularly in winter.
They develop a reduction in winter hardiness due to an impaired ability to retain water. The beneficial mycorrhizal fungi that colonize many types of plant roots are particularly sensitive to ammonia. Reductions in mycorrhizal fungi on tree roots may be the reason for reduced water retention in conifers. Conifer forests and sphagnum bogs are particularly at risk if sufficient ammonia is added over time. Conifers may experience a form of eutrophication, and sphagnum cannot compete with grasses under increased ammonia conditions.