Floods are a natural occurrence in every river system and can damage valuable infrastructure and buildings located in flood zones. In the Mohawk River watershed there are four main types of flood events for which management strategies are required:
- Spring breakup, Snowmelt and Winter Rains - The annual breakup and thaw produces regular flooding associated with rising temperatures and thaw of stored waters from winter-accumulated snow. Ice jamming during these events provides a unique component to this hazard. Some of the most significant floods in the watershed have been winter rain on snow events, such as the January 1996 event in Burtonsville, NY which is the second highest recorded peak flow on the Schoharie Creek.
- Cyclonic disturbances - Precipitation from large-scale atmospheric systems such as hurricanes, remnants of hurricanes, and stalled frontal systems can produce enormous quantities of rain in the watershed. Climate change is projected to increase the frequency of severe cyclonic events and may permit more northward tracking of hurricanes.
- Localized summer outburst events - Thunderstorms and other summer disturbances that result in intense local precipitation may cause severe or flash flooding in small tributaries. An event in July 2008 caused intense scour, sediment transport, and over $3 million in damage to infrastructure in Schenectady County.
- Catastrophic release of impoundments - The failure of upstream impoundments (i.e., reservoirs) could cause devastating floods in the watershed. A catastrophic event of this type has not occurred yet, but dam-break analyses have shown how problematic such an event would be.