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BC aquifer 9 · sand and gravel · 13 km² · Fraser Valley
Aquifer 9: Chilliwack River Shallow
Aquifer 9 (Chilliwack River Shallow) is an unconfined sand and gravel (medium stream system) aquifer of 13 km² in the Fraser Valley regional district, mapped in 2019. The province rates its productivity not rated, its vulnerability to contamination from the surface high, and the demand on it not rated. 42 wells on record are linked to it; water-supply wells there are typically 15.2 m deep and tested at a median 104 L/min.
How the province rates it
Productivity not rated, vulnerability high, demand not rated.
| Rating | What it means | |
|---|---|---|
| Productivity how much water the aquifer gives up to wells, judged from well yields, the aquifer material and pumping tests | not rated | The province hasn't rated this for this aquifer. |
| Vulnerability how easily something spilled at the ground surface could reach the water, judged from what lies above the aquifer and how deep the water is | high (class A) | Little natural protection (the guide's class A): a shallow water table or sand and gravel above it lets surface water and spills soak down quickly. |
| Demand how much the aquifer is used now, judged from the number and density of wells and what they're used for | not rated | The province hasn't rated this for this aquifer. |
| Level of development Inferred demand compared with productivity | unclear | Unclear: the province hasn't rated both demand and productivity. |
Ratings are the province's, set when the aquifer was mapped (2019) from wells, geology and local studies. Vulnerability is about the ground, not what's built on it: a well-protected aquifer under a busy area can still be at more risk than an exposed one in the bush.
Sources: Ground Water Aquifers, Water Protection and Sustainability Branch, Province of BC and Groundwater Wells (GWELLS), Province of BC, as published on October 1, 2026 (Open Government Licence – British Columbia); ratings explained after Berardinucci and Ronneseth (2002), Guide to Using the BC Aquifer Classification Maps for the Protection and Management of Groundwater, BC Ministry of Water, Land and Air Protection. Summaries by PlaceDossier.
The wells in it
42 wells on record are linked to this aquifer.
| Wells linked | 42 (33 water-supply) |
|---|---|
| Water-supply well depth | median 15.2 m; middle half 8.2 m to 20.1 m (33 wells) |
| Tested yield | median 104 L/min; middle half 71 L/min to 199 L/min (24 wells tested) |
| Water level below ground | median 3 m when drilled (26 wells) |
| Drilled | 1901 to 2010 |
This aquifer's medianIts middle half of wellsAnother BC aquifer's median
Depths are how deep the driller finished the well; yields are the driller's test, often an hour or less, in litres per minute. A domestic well's yield is usually judged against the household's peak use; ask a driller what's enough for yours.
Where it is
Outline simplified by us from the provincial map; not for locating a lot. It lies under Fraser Valley, Electoral Area E (46%), Fraser Valley, Electoral Area H (20%).
| Kind | Unconfined sand and gravel aquifer - medium stream system |
|---|---|
| Geological unit | Holocene Fluvial, include Sumas Outwash by Cultus Lake |
| Location, as described | Chilliwack River; Cultus Lake |
| Area | 13 km² |
| Water use | Household wells |
| Water quality concerns | None documented |
| Mapped | 2019 |
Unconfined: nothing tight lies over it, so rain and surface water soak straight down to it; the water table rises and falls with the seasons. The province's page for this aquifer lists the studies behind it and its observation wells: GWELLS aquifer 9.
Sources: Ground Water Aquifers, Water Protection and Sustainability Branch, Province of BC and Groundwater Wells (GWELLS), Province of BC, as published on October 1, 2026 (Open Government Licence – British Columbia); ratings explained after Berardinucci and Ronneseth (2002), Guide to Using the BC Aquifer Classification Maps for the Protection and Management of Groundwater, BC Ministry of Water, Land and Air Protection. Summaries by PlaceDossier.
What this record doesn't cover
The province maps aquifers where wells and studies give enough to go on, mostly in settled valleys; most of BC isn't mapped, and a lot outside every outline can still have groundwater. Outlines are drawn from geology and well logs at the scale of the study, so an edge can be well off on the ground, and one aquifer can lie under another. Wells are linked to an aquifer by provincial staff from the driller's log: not every well inside an outline is linked, and well depths and yields are as the driller reported them, often from a short test.
These are mapped ratings and drillers' records, not a test of any one lot. Before you buy a property on a well, or plan to drill, ask a qualified hydrogeologist or a registered well driller what this aquifer gives where you are, and test the water.