A storm surge is a short term rise or fall in sea level due to strong winds. The actual size of the surge is often accentuated in shallow water or along shorelines and is also affected by both wave size and tide height. Due to the fact that surges that result in a rise in sea level have the greatest impact on human activities, these types of surges are typically of most interest. In the Mackenzie Delta area, surges that increase sea level are the result of strong offshore winds from the Beaufort Sea. Although they may occur when the Beaufort Sea is ice covered, typically they are largest during the ice free period In the Tuktoyaktuk area the estimated maximum storm surge elevation with an approximate 100-year return period is 2.4 m. Such storm surges flood large areas along the Beaufort coast, flood much of the lower Mackenzie Delta, and result in a rise in water levels as far upstream as Tsiigehtchic (formerly Arctic Red River).