On an emergency basis during the summer of 2021, the Yukon Government (YG) responded to unprecedented flooding in the Southern Lakes region of the Yukon. Historic snow fall amounts combined with warmer than normal summer temperatures resulted in historic flood levels. Both public and private infrastructure and property were at risk of flooding. The emergency response team was led by YG with critical assistance on engineering and construction by KGS Group and the Canadian Armed Forces, respectively.
This currently estimated 1:1000 event has affected shorelines, residences and infrastructure along Marsh Lake, Tagish Lake, Lake Laberge, and Nares and Bennett Lakes in Carcross. Emergency works were constructed during a critical one-month period along an estimated 10 km of combined shoreline. The magnitude and logistics of the response required a variety of diking systems be employed including conventional poly-wrapped sand dikes, sandbag dikes, super sandbag dikes, concrete lock-block wall dikes, and aqua dams. All works were constructed under emergency conditions to provide increased protection against the forecasted flood levels and wave action. Most dikes were founded on pervious coarse grained beach deposits, such that undermining, seepage, piping, and blowouts were a major risk to the integrity of the dikes. Internal drainage was also a major risk and needed to be controlled from both seepage and overland drainage perspectives.
The technical and logistical lessons learned places the Yukon Government in a better position to address future flood events with respect to overall emergency flood protection planning and implementation.
