Риски наводнений и землетрясений в Нижнем Мейнленде.

The Lower Mainland is considered to have a high vulnerability to flood risk. There have been two major region wide floods in 1894 and 1948, both associated with an extreme spring freshet of the Fraser River. Other major floods in the Lower Mainlandincluding June 1972, November 1990, and November 2021have been more localized, primarily impacting areas in the Fraser Valley like the Sumas Prairie, with comparatively minor impacts to Metro Vancouver. Prior to the 2021 flood, according to the Fraser Basin Council, scientists predicted a one in three chance of a similar sized flood occurring in the next 50 years. In the second quarter of 2007, the Lower Mainland was on high alert for flooding. Higher than normal snow packs in the British Columbia Interior prompted municipal governments to start taking emergency measures in the region. Dikes along the Fraser River are regulated to handle approximately at the Mission Gauge (the height above sea level of the dykes at Mission). Warmer than normal weather in the province's Interior region caused large amounts of snow to melt prematurely, resulting in higher than normal water levels, which, nevertheless, remained well below flood levels. Flooding can cover much of the Lower Mainland. Cloverdale, Barnston Island, low lying areas of Maple Ridge, areas west of Hope, White Rock, Richmond, parts of Vancouver, and parts of Surrey are potentially at risk. In 2007, the Lower Mainland was largely spared, although northern regions of the province, along the Skeena and Nechako Rivers, experienced floods. Climate scientists predict that increasing temperatures will mean wetter winters and more snow at the high elevations. This will increase the likelihood of snowmelt floods. The provincial government maintains an integrated flood hazard management program and extensive flood protection infrastructure in the Lower Mainland. The infrastructure consists of dikes, pump stations, floodboxes, riprap, and relief wells.

While earthquakes are common in British Columbia and adjacent coastal waters, most are minor in energy release or are sufficiently remote to have little effect on populated areas. Nevertheless, earthquakes with a magnitude of up to 7.3 have occurred within of the Lower Mainland. Based on geological evidence, however, stronger earthquakes appear to have occurred at approximately 600 year intervals. Therefore, there is a probability that there will be a major earthquake in the region within the next 200 years. In April 2008, the United States Geological Survey released information concerning a newly found fault south of downtown Abbotsford, called the Boulder Creek Fault. Scientists now believe this fault is active and capable of producing earthquakes in the 6.8 magnitude range.

Much of the Lower Mainland is vulnerable to explosive eruptions from the Garibaldi Volcanic Belt. Volcanoes in this zone are capable of producing large quantities of volcanic ash that may cause short and long term water supply problems for Lower Mainland communities. All airports covered by the accompanying eruption column would be closed, heavy ash falls would damage electrical equipment and weak structures could collapse under the weight of the ash.

The Lower Mainland's communities includes large cities in Metro Vancouver, and smaller cities, towns and villages along both banks of the Fraser River. Neighbourhoods within cities are not listed unless historically or otherwise notable and/or separate. Only some of the many Indian Reserves are listed.