Nanaimo River Flood Hazard Study Underway

The Nanaimo River is part of the Georgia Basin drainage network located on central Vancouver Island. The Nanaimo River watershed ranges from the Island Range to sea level, draining through Jump Lake into the Strait of Georgia within the boundaries of the City of Nanaimo, Snuneymuxw Reserve Lands and the RDN, Electoral Area A.

As with other rivers in the region, the Nanaimo River is primarily a rain-driven hydrologic system, influenced by heavy fall and winter rain or snow. The majority of the flow occurs in the fall and winter with low discharge in the summer period. The Nanaimo River floodplain has been designated by the Government of BC as a “high risk” floodplain. The river has a long-standing history of flooding, with extreme events due to a combination of rainfall and high tide, such as in 1949, 2007and 2014. The most recently extreme event was in January 2020, triggering the temporary displacement of on-reserve and Electoral Area A residents.

The existing floodplain map for the Nanaimo River, issued by the Province of BC in May 1984, are considered outdated because the hydrologic model used to create the map does not consider upstream and downstream changes in the watershed, regional climate allowances nor the influence of rising sea levels. This project is designed to address this issue by conducting a hydrologic analysis, including climate change forecasting and subsequent hydraulic modeling. The key output of this work will be up-to- date riverine floodplain regulatory map and to complete a risk assessment informed by these findings and key stakeholder including the City of Nanaimo and Snuneymuxw First Nation.

The project timelines are October 2021 to March 31, 2022.