Water Supply Glossary

[glenncampagna]

For listing and defining important terms relating to water supply
The VA 2020 State Plan defines lots of vocab

• Regional planning units: the groups of localities that are working together for their water supply planning [map: #855]
• Localities : most often counties, who are responsible for their own data collection. Can be part of a larger region with other localities
• Facilities: individual entities which report their own data, and may include multiple intakes (even from different river segments). All viewable in vahydro
• Systems : within each locality and can be a single facility or made up of multiple interconnected facilities (ex. interconnected reservoirs). Useful for the supply planning perspective
  • Statement of Need: included in regional supply plans, and addresses whether future water supply will be adequate for projected demands. Alternatives act as potential solutions
• Alternatives: plans for meeting water demands when supply is insufficient
• Exempt Users: facilities in operation prior to new permit regulations in 1982 which have been 'grandfathered in' , meaning they are not required to have a permit and use is based on a figure given by the facility. If ownership changes or major changes are made, a permit must be obtained
• Stream Order: method of assigning numeric order to links in a stream network based on # of tributaries. There are 2 methods, and Strahler is the most common (source)
• Use vs. Withdrawals: these terms are used interchangeably in vahydro, and corresponding values can be slightly different in places where one value/metric has been more recently updated

  Metrics

• 7Q10: A single numeric metric of the lowest 7 day average streamflow that occurs on average once every 10 years.
• L90: The lowest 90 day average for daily streamflow(on consecutive days) over the simulation period. This will represent a prolonged drought whereas a L30 represents a short term/acute drought.

[glenncampagna]

Demand Categories

• CWS: Community Water System refers to a water system serving at least 15 service connections or 25 residents year-round.
• Small SSU: Small Self-Supplied User is a residence or business relying on wells and withdrawing less than 300,000 gallons of groundwater per month.
• Large SSU: Large Self-Supplied User is a user of over 300,000 gallons of surface water or groundwater for non-agricultural uses
• AG: Agricultural Self-Supplied User is an agricultural operation using more than 300,000 gallons of surface water or groundwater per month

[glenncampagna]

Supply planning vocab. from 5/22/23 presentation

- Statement of Need: included in regional supply plans, and addresses whether future water supply will be adequate for projected demands. Alternatives act as potential solutions - Alternatives: plans for meeting water demands when supply is insufficient

From 5/25/23 Meeting

• Localities, most often counties, can be part of a larger Region with other localities
• Systems, such as specific facilities and users, are within each locality
• Data-collection happens at the locality-level while future supply planning is to be done regionally #855

[EllaF21]

Metrics Vocab

-Low flow statistics: Looking at an estimated lowest flow event in rivers/streams that would occur over a specific period of time. They are expressed in terms of averaging periods and their recurrence frequency(4 day average flow once every 10 years). A low flow is what the flow of water in a stream is during very dry weather for prolonged time periods.

• 7Q10: A single numeric metric of the lowest 7 day average streamflow that occurs on average once every 10 years.

• L90: The lowest 90 day average for daily streamflow(on consecutive days) over the simulation period. This will represent a prolonged drought whereas a L30 represents a short term/acute drought.