It is illegal to manually water your lawn while it is raining.

The Law

To combat the sheer absurdity of wasting city water, Sheboygan passed an ordinance forbidding the use of sprinklers or garden hoses during active rainstorms. This law targets overly fastidious homeowners who leave their automatic sprinkler systems running regardless of the actual weather. It is a practical conservation law disguised as a rule against foolishness.