Water Supply Reliability

The availability or provision of water of sufficient quantity and quality to meet water needs for health and economic well-being and functioning.

Associated Indicators

Earthquake Resilience

The maximum earthquake intensity that can occur without causing more than some amount (e.g., $20 million) in damages due to water infrastructure disruptions, including levees

Groundwater Nitrate

Groundwater describes water in soil and sub-soil substrates (e.g., aquifers) that is replenished across various time-frames by surface water that percolates to these underground reservoirs. For this water to be useable to meet human needs (e.g., drinking, irrigation) it must meet the same kinds of water quality requirements as surface water. One indicator of groundwater quality is nitrate concentration.

Groundwater Stress (WRI)

Groundwater stress measures the ratio of groundwater withdrawal relative to its recharge rate over a given aquifer. Values above one indicate where unsustainable groundwater consumption could affect groundwater availability and groundwater-dependent ecosystems. The indicator was used by the World Resources Institute (WRI) in the Aqueduct 2.0 project.

Impervious Surface: Geomorphic Condition

Proportion of watershed covered by impenetrable materials such as roads, parking lots, and buildings preventing water from leaching directly into the soil. The greater the proportion of watershed with impervious surfaces, the greater the likelihood of geomorphic processes and conditions being degraded due primarily to modifications of stormwater runoff dynamics.

Managed Geomorphic Flows

Magnitude and timing of managed system flows suitable for native riparian habitats and geomorphic processes. Healthy aquatic, riparian, and floodplain ecosystems require periodic high flow events, not just minimum flows.

Non-potable Water Needs for Agriculture

Proportion of agricultural non-potable water needs--e.g. irrigation--met with non-potable water. The more non-potable water used for agriculture, the more potable water is available for drinking water and healthy aquatic ecosystems.

Percent Recycled Water

Use of recycled water as a percent of total water used. Re-using water reduces the demand on existing and new water sources and reduces costs and impacts.

Protected Aquifer Recharge Areas

Number of acres protected or enhanced in aquifer recharge areas. Natural recharge of underground water reservoirs may be the most cost-effective way to store and manage water.