Legal Definitions - surplus water

Surplus water refers to water that is available in a particular source (such as a river, lake, or groundwater aquifer) but is not currently being used or legally reserved to satisfy existing beneficial uses or established water rights. It represents the amount of water that exceeds what is necessary to meet all current, legitimate demands and entitlements within a given water system.

This excess water may become available for new appropriations, transfers, or other purposes, often under specific legal frameworks that prioritize certain types of use, ensure environmental protection, or facilitate reallocation during times of scarcity.

• Example 1 (Agricultural Context): A large agricultural cooperative holds a senior water right to divert a substantial volume of water from a regional river for irrigating its members' crops. Following an exceptionally wet spring with prolonged rainfall, the cooperative's fields receive ample natural moisture, significantly reducing their need for irrigation. The portion of their allocated water right that the cooperative does not divert or use because it is not needed for beneficial irrigation purposes would be considered surplus water in that specific season. This surplus might then be available for downstream users with junior rights, or it could contribute to environmental flows, depending on the governing water laws.

  Explanation: The cooperative has a legal right to a certain amount of water for a beneficial use (irrigation). However, due to external circumstances (heavy rain), they do not need to use their full allocation. The unused portion, beyond what is required for their current beneficial use, is considered surplus.

• Example 2 (Municipal Context): A growing city manages a large reservoir that supplies drinking water to its residents. Through aggressive water conservation programs, the implementation of drought-resistant landscaping ordinances, and the development of advanced wastewater recycling facilities, the city successfully reduces its overall water consumption. As a result, the reservoir consistently holds more water than is required to meet the current and projected municipal demands. This excess water, beyond what is necessary for the city's established beneficial use, is classified as surplus water. The city might then explore options such as selling this surplus to a neighboring community facing water shortages or dedicating it to replenish local groundwater aquifers.

  Explanation: The city has a primary beneficial use for the water (municipal supply). However, due to successful conservation and alternative water sources, its actual needs are less than the available supply. The difference is water that is surplus to its current beneficial use.

• Example 3 (Industrial and Environmental Context): A manufacturing plant holds a permit to extract a specific volume of water from a local river for its cooling processes. Over time, the plant invests in new, more efficient cooling technologies that significantly reduce its water intake requirements. The difference between the permitted amount of water and the actual, reduced amount the plant now needs for its beneficial industrial operations represents surplus water. This surplus water could then be reallocated by water management authorities to support a nearby wildlife refuge during dry periods or to maintain minimum instream flows necessary for aquatic ecosystems.

  Explanation: The manufacturing plant has a legal right to use water for an industrial purpose. However, technological improvements have reduced its operational need for that water. The unused portion, no longer required for its beneficial use, becomes surplus and potentially available for other uses, including environmental ones.