Island homes drink groundwater. Every figure here is the Province of British Columbia's own — from its aquifer mapping and its GWELLS well registry — shown verbatim and linked to source. The Province maps 4 aquifers beneath Mayne Island's 1,620 land lots, carrying 367 registered wells, 9 of them with provincial water-chemistry data, and 6 provincial observation wells recording long-term water levels.
Bedrock — Fractured sedimentary rock; 8.0 km²; mapped 2006. Beneath 536 of Mayne Island's lots.
Vulnerability Moderate; productivity Low; demand Moderate; quality concern Regional. Rock unit: Fractured sedimentary bedrock of Upper Cretaceous Nanaimo Group.
137 wells on record; 2 water licences; 13 artesian; 2 wells with provincial water-chemistry data; 2 provincial observation wells (#129 Inactive, #127 Inactive).
Bedrock — Fractured sedimentary rock; 7.7 km²; mapped 2006. Beneath 494 of Mayne Island's lots.
Vulnerability Moderate; productivity Low; demand Moderate; quality concern Regional. Rock unit: Fractured sedimentary bedrock of Upper Cretaceous Nanaimo Group.
114 wells on record; 2 water licences; 2 artesian; 1 wells with provincial water-chemistry data; 1 provincial observation well (#125 Active).
Bedrock — Fractured sedimentary rock; 3.7 km²; mapped 2006. Beneath 317 of Mayne Island's lots.
Vulnerability High; productivity Low; demand Moderate; quality concern Local. Rock unit: Upper Cretaceous; Nanimo Grp; Gabriola & Spray Formations.
63 wells on record; 1 water licence; 1 artesian; 4 wells with provincial water-chemistry data; 2 provincial observation wells (#126 Inactive, #128 Active).
Bedrock — Fractured sedimentary rock; 3.9 km²; mapped 2006. Beneath 270 of Mayne Island's lots.
Vulnerability Moderate; productivity Moderate; demand Moderate; quality concern None. Rock unit: Upper Cretaceous; Nanimo Group; Gabriola & Spray Formations.
53 wells on record; 1 artesian; 2 wells with provincial water-chemistry data; 1 provincial observation well (#484 Active).
The Province classifies each mapped aquifer's intrinsic vulnerability — how easily contamination at the surface could reach the water — as Low, Moderate or High, based on factors like depth to water and what covers the aquifer. A High rating means relatively little natural protection between the surface and the water people draw from. It describes susceptibility, not current contamination. Productivity describes how readily the aquifer yields water; demand describes the level of use. These are the Province's classifications, not ours.
Most Gulf and Northern Gulf island aquifers are fractured rock: water sits in cracks in sedimentary or crystalline bedrock rather than in a porous bed of sand and gravel. Fractured-rock aquifers store comparatively little water and move it unevenly, which is why neighbouring wells on the same island can report very different yields, and why the Province rates most of these aquifers Low productivity.
Aquifer boundaries are a toggleable layer on the island map. This page presents provincial data with explanatory context; it makes no claims about individual wells or properties.