The Omaka Aquifer underlies the Omaka-Hawkesbury Valley.
Because of the ephemeral nature of the local Wards/Mill Stream, groundwater is the primary source of water for the area over summer.
The photo features Marlborough's deepest well, drilled by Marlborough District Council to a depth of 400 metres beside Hawkesbury Road in the mid 1990s.
At the time it demonstrated that no new, high-yielding aquifers existed in this area.
The Omaka Aquifer consists of a number of water-bearing layers stacked one on top of another, each with a distinct static water level or pressure. For example; the depth to the water table in shallow wells is maybe 5 metres, compared to 25 metres for the exploratory well.
Both losses from the local stream and rainfall recharge the aquifer in winter and spring.
The aquifer is used for a variety of purposes including drinking, vineyard irrigation and, to a limited extent, stock supply.