What term refers to underground layers that can yield groundwater to wells?

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An aquifer is an underground layer of permeable rock or sediment that can store and transmit groundwater, making it capable of yielding water to wells. The water is held in the pore spaces and fractures within that material, allowing it to move and be pumped up. In contrast, a reservoir refers to storage of water (often surface water), pores are just the tiny voids in the material and don’t by themselves designate a water-producing layer, and an aqueduct is a channel to transport water, not an underground layer that yields groundwater.