Trapping and Wetland regulations in each state and province are different. Check with your Department of Wildlife or Environmental Protection for the the regulations in your region.
In Massachusetts, recreational beaver trapping season starts November 1st and ends April 15th each year. Only live catch traps are allowed and no permit is necessary for a state licensed trapper to trap beaver during trapping season. However, at any time of year if there is a beaver-related threat to human property, health or safety, the local Board of Health can issue a 10 Day Emergency beaver permit to trap the beaver using lethal Conibear traps, breach the dam, and/or install a flow device.
In MA, Conservation Commission wetland permitting is also needed to breach a beaver dam or install a water control device. When Board of Health issues a 10 Day Emergency beaver permit the process is expedited. No public hearing is needed. The local Conservation Agent will simply review the plan to breach the dam or install a flow device and they will issue an Emergency wetland permit with any conditions they deem appropriate. Their job is to ensure that any negative impact to the wetland resource is minimized.