Aquifer
Definition
An aquifer is a subsurface geological formation that contains sufficient saturated permeable material to yield usable quantities of water to wells. Aquifers are divided into two main types: unconfined aquifers, where the water table is at the top of the saturated zone and is recharged directly by precipitation and surface water; and confined aquifers, which are bounded above by an impermeable layer and are under pressure. In Northern Idaho, the primary aquifer system is the unconfined Spokane Valley–Rathdrum Prairie (SVRP) Aquifer — a highly productive glacial gravel and sand aquifer that supplies water to residential wells, municipal systems, and agricultural operations across Kootenai and Bonner Counties. In other parts of the service area, water is found in fractured basalt formations rather than a traditional aquifer.
Frequently Asked Questions
Why Aquifer Matters
How Trident Drilling Company Uses It
Trident Drilling assesses the likely aquifer type for each project site using geological data, IDWR records, and local lithology logs. This assessment informs drilling method selection, depth estimates, and expected yield ranges communicated to the client before drilling begins.