Manure on Snow, Discharges
from Michigan's GAAMPs:
"Application of manure to frozen or snow-covered soils should be avoided..."

"Frozen soils and snow cover ...greatly increase the risk of manure being lost to surface waters
by runoff and erosion during thaws or early spring rains."

The photo below shows manure running off snow into a drain that leads to Hazen Creek.  The CAFO was cited by the Michigan Department of Environmental Quality for an illegal discharge -- but in this case, as in all cases, there have been no fines or penalties.