A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

Radius of Influence
The horizontal radial distance from a well to the points in an aquifer where there is no observable influence from pumping.

Raw Water
Untreated water of any kind.

Recharge
The downward movement (percolation) of rain, snowmelt or surface water through the soil, weathered material and rock layers to replenish the ground water/aquifer stores. Concentrated zones of ground water recharge may occur through stream beds.

Recharge (artificial)
Water added by flooding basins or recharge wells to increase the volume of water stored in an aquifer.

Recharge (natural)
Water added to an aquifer. For instance, rainfall that seeps into the ground or natural leakage from river beds to aquifers.

Reclaimed Wastewater
Treated wastewater that can be used for beneficial purposes. Golf course Irrigation and aquifer recharge are users of reclaimed water.

Recycled Water
Water that is used more than one time before it passes back into the natural hydrologic system.

Regolith
The layer of unconsolidated material overlying bedrock. Such material may have been transported or have been formed in place by weathering processes. The weathered regolith may provide an important zone of ground water storage for wells that are drilled into bedrock beneath the regolith layer.

Reservoir
A pond, lake, or basin, from which water is diverted or pumped for purposes of supply or river control. The term reservoir is usually used to describe impoundments that may be on-channel or off-channel. Some impoundments have been constructed to increase natural lake storage capacity.

Returnflow (Irrigation)
Irrigation water that is applied to an area and which is not consumed in evaporation or transpiration and returns to a surface stream.

Reverse Osmosis
The process of removing salts from water using a membrane. Pressure from a pump is used to reverse the normal osmotic process resulting in the solvent moving from a solution of higher concentration to one of lower concentration. The water passes through a fine membrane that the salts are unable to pass through, the remaining salt waste (brine) is removed.

Riparian Habitat
Area adjacent to lakes streams & rivers important for plants and wildlife. Riparian areas are often protected by laws requiring "buffer strips" that can't be developed or cultivated.
See also BMP.

Riparian Water Rights
The rights of an owner whose land abuts water. They differ from state to state and often depend on whether the water is a river, lake, or ocean. The doctrine of riparian rights has its origins in English common law. Persons who own land adjacent to a stream have the right to make reasonable use of the stream. Riparian users of a stream share the streamflow among themselves. Riparian rights cannot usually be sold or transferred for use on non-riparian land.
See also Prior appropriation.

Rotary Drilling
A well drilling method achieved by the rotary action of a drill bit. The ground-up rock is removed by circulating drilling mud which may be forced down the drill pipe and out via the annular space between the drill pipe and the hole. If casing is installed as the drilling proceeds then reverse-rotary drilling may be used with the drilling fluid being pumped down the outside of the drill pipe and returned to the surface upwards through the drill pipe.

Runoff
The movement of water over the surface of the land, derived from snowmelt or rainfall (as opposed to water infiltrating the ground and moving to streams as baseflow). Runoff is often used generally to describe surface water flow associated with storm rainfall.