Glossary

a geologic formation of permeable rock, sand or other material that holds and allows the flow of water.

an aquifer located between layers of relatively impermeable material (like clay or shale) and it is under pressure.

an aquifer where its upper surface (water table) is open to the atmosphere through permeable material. The water table in an unconfined aquifer rises and falls depending on the amount of water entering or leaving the aquifer.

a geologic formation that has low permeability and does not transmit water easily.

a distinct area underlain by permeable materials and bounded by geological barriers, capable of storing and transmitting significant quantities of groundwater. A subbasin is a smaller division within a groundwater basin that can have slightly different hydrological characteristics.

a groundwater user that extracts, for domestic purposes, two acre-feet or less per year.

the state agency that manages California’s water resources and oversees the implementation of Sustainable Groundwater Management Act (SGMA).

a man-made waterway used to divert water from one location to another. Diversion canals are used for a variety of purposes, such as irrigation, flood control and water supply.

a geographic area where all the water that falls as precipitation drains into a common outlet such as a river, lake or ocean.

a lowering of the water level in an aquifer or reservoir, typically because of pumping or extraction.

a process by which water is transferred from the land to the atmosphere by evaporation from the soil and other surfaces and by transpiration from plants.

water that resides beneath the Earth’s surface in rock crevices and in the pores of geologic materials.

a process through which water from the surface percolates down through the soil and rock layers replenishing the aquifers. Rain, snow and surface water bodies are the primary natural sources of recharge. Artificial or managed recharge methods include spreading basins, recharge wells and restoration of wetlands.

a public agency formed to manage groundwater resources in a specific area, particularly in the context of the Sustainable Groundwater Management Act (SGMA).

a comprehensive planning document developed by a Groundwater Sustainability Agency to manage and use groundwater resources sustainably.

a type of well used to inject fluids into underground formations. These wells are designed for various purposes, including waste disposal, enhanced oil recovery and groundwater recharge.

a water management strategy where an alternative water source is used as a substitute to the typical source, with the goal of conserving the latter.

a specific quantitative target established by a Groundwater Sustainability Agency (GSA) for various sustainability indicators of a groundwater basin. It represents the basin’s desired groundwater conditions and allow the GSA to achieve its sustainability goals.

a specific quantitative limit established by a Groundwater Sustainability Agency (GSA) for various sustainability indicators of a groundwater basin. It represents the groundwater conditions at a representative monitoring site that, when exceeded individually or in combination with minimum thresholds at other representative monitoring sites, may cause an undesirable result(s) in the basin.

a type of well used for the purpose of monitoring various characteristics of groundwater, such as its level, quality, and movement.

a situation where groundwater is being extracted at a rate faster than it is being replenished or recharged.

an individual or entity that owns and operates private wells for extracting groundwater, usually for their own use.

a process where seawater flows into freshwater aquifers, which typically occurs along coastal areas. Seawater intrusion can significantly impact freshwater resources, making them saline and unsuitable for most uses without costly treatment. Learn more.

a required component of the Sustainable Management Criteria that Groundwater Sustainability Agencies (GSAs) must develop for the entire groundwater basin. The sustainability goal must succinctly state the GSA’s objectives and desired conditions of the basin, how the basin will reach that desired condition and why the measures planned will lead to success.

a legislative framework enacted by the State of California in 2014 to regulate groundwater use and promote sustainable management of groundwater resources.

a critical factor that Groundwater Sustainability Agencies (GSAs) must address in their Groundwater Sustainability Plans (GSPs). Sustainable Management Criteria include:

• Sustainability Goals
• Undesirable Results
• Minimum Thresholds
• Measurable Objectives

water that collects on the surface of the Earth, such as in streams, rivers, lakes, wetlands or reservoirs.

a critical factor that Groundwater Sustainability Agencies (GSAs) must address in their Groundwater Sustainability Plans (GSPs). The six undesirable results are:

• Chronic lowering of groundwater levels
• Reduction of groundwater storage
• Seawater intrusion
• Degraded water quality
• Land subsidence
• Depletions of interconnected surface water

top of the water in the ground, where the soil or rocks are permanently saturated with water.

a term commonly used in hydrology and water resource management to describe a specific 12-month period. In California, the water year starts on October 1 and ends on September 30.

a term commonly used in hydrology and water resource management to refer to the various ways in which water is utilized by humans including domestic, agricultural, industrial and recreational purposes.