Gabriola has the busiest groundwater in the Islands Trust area — and the Province watches it more closely than any other island aquifer it maps.
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 2 aquifers beneath Gabriola Island's 4,047 land lots, carrying 1,299 registered wells, 80 of them with provincial water-chemistry data, and 7 provincial observation wells recording long-term water levels.
Bedrock — Fractured sedimentary rock; 46.8 km²; mapped 2004. Beneath 2,659 of Gabriola Island's lots.
Vulnerability High; productivity Low; demand Moderate; quality concern Local.
1,042 wells on record; 1 water licence; 6 artesian; 67 wells with provincial water-chemistry data; 7 provincial observation wells (#195 Inactive, #197 Active, #385 Active, #316 Active, #317 Inactive, #194 Inactive, #196 Active).
Bedrock — Fractured sedimentary rock; 5.9 km²; mapped 2004. Beneath 727 of Gabriola Island's lots.
Vulnerability High; productivity Low; demand High; quality concern Local.
257 wells on record; 1 water licence; 1 artesian; 13 wells with provincial water-chemistry data.
Provincial mapping splits Gabriola into two bedrock aquifers — the main island aquifer and a separate northern one — both fractured sedimentary rock, both rated High vulnerability and Low productivity. Between them they carry far more registered wells than any other island in this network. The northern aquifer is the smaller of the two by area but carries a demand rating of High.
The Province maintains a network of observation wells that record long-term water levels. Gabriola's main aquifer has more of them than any other aquifer beneath an Islands Trust island in the provincial data mirrored here. A dense monitoring network is not itself evidence of a problem — but it is where the evidence would show up first, and it means Gabriola's groundwater has a measured record rather than an assumed one.
The Gabriola Island Local Trust Area also covers De Courcy, Mudge, Link and Ruxton. The De Courcy Island aquifer is mapped separately, rated High vulnerability with a demand rating of High on a footprint of only a couple of square kilometres.
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.