Water Terms

Absolute Water Right

A property right to put water to a specific beneficial use, in a specified portion, in accordance with its priority.

Acre-Foot

A volume of water equal to one foot in depth covering an area of one acre. Also 43,560 cubic feet, or 325,851 gallons. Used to measure stored water quantities. An acre-foot is a volume approximately sufficient to supply the needs of a single family of four for one year.

Adjudication

Judicial proceedings before the State of Colorado Water Court to hear and decide a water rights case. Alluvial Water Ground water that is hydrologically connected to a surface stream, and is present in permeable soil material, usually sands and gravels.

Appropriate

To take the legal actions necessary to create a right to divert water from a stream, tributary or aquifer for application to beneficial use.

Appropriation

The right to take water from a stream, tributary or aquifer for beneficial use at a specified rate of flow, when such right is in priority, either for immediate use or to store for later use. Usually evidenced by a water court decree.

Aquifer

An underground deposit of sand, gravel or rock through which water can pass or is stored. Aquifers supply the water for wells and springs.

Augmentation Plan

A court-approved plan that allows water users to divert water out of priority so long as adequate replacement is made to the affected stream system, thereby preventing injury to the water rights of senior users.

Augmentation Source

The supply of water used to replace out-of-priority depletions.

Beneficial Use

Application of water without waste for the purposes for which the appropriation is lawfully established.

Call

When there is insufficient water in a stream, river, or aquifer to meet the water right of a senior user, the senior water right holder may place a “call” on the river. When a call is present during water-short time periods, upstream junior water right holders may be required to reduce or cease their use of water to allow water to flow to the senior right holder.

Clean Water Act

The federal law that sets forth how the United States will restore and maintain the chemical, physical and biological integrity of the country’s waters (oceans, lakes, stream and rivers, ground water and wetlands). The law provides protection to the country’s surface waters from both point and non-point sources of pollution.

Colorado Doctrine

The right to take water from a stream, tributary or aquifer for beneficial use at a specified rate of flow, when such right is in priority, either for immediate use or to store for later use. Usually evidenced by a water court decree.

Colorado Water Conservation Board

The state agency vested with the exclusive authority to appropriate waters of natural streams and lakes as determined may be required for minimum stream flows and volumes for natural lakes, in amounts that are determined to be necessary to preserve the natural environment to a reasonable degree.

Compact

A contract between states that is ratified by those states’ legislatures and by the U.S. Congress. The contract controls the division of water in a river system that flows across state boundaries.

Conditional Water Right

The legal establishment of a priority date that provides a water user time to develop his or her water right, before physically putting the water to beneficial use. A conditional right becomes an absolute right when water is actually put to beneficial use.

Conservancy District

Established by decree of a court under the Water Conservancy District Act of 1937. Among other powers, a conservancy district can obtain rights-of-way for works; contract with the United States or otherwise provide for construction of facilities; assume contractual or bonded indebtedness; administer, operate, and maintain physical works; have authority to conserve, control, allocate, and distribute water supplies; and have contracting and limited taxing authority to derive the revenues necessary to accomplish its purposes. There are currently 48 conservancy districts in Colorado.

Conservation

Obtaining the benefits of water more efficiently.

Conservation District

Established under specific statues by the Colorado General Assembly. There are currently three conservation districts in Colorado the Colorado River Water Conservation District, the Southwestern Water Conservation District, and the Rio Grande Water Conservation District. The mission is to oversee the conservation, use, and development of water in large geographical areas of the state.

Consumptive Use

Any use of water that permanently removes water from the natural stream system.

Continental Divide

An imaginary boundary line that runs north-south along the crest of the Rocky Mountains, separating river and drainages that flow west to the Pacific Ocean from those that flow south and east to the Gulf of Mexico.

Cubic Feet per Second (CFS)

A rate of water flow at a given point, amounting to a volume of one cubic foot for each second of time. Equal to 7.48 gallons per second, 448.8 gallons per minute, or 1.98 acre feet per day.

Decree

A final court decision regarding a water rights case. Once a decree has finalized a water right, the right is administered by Colorado’s Division of Water Resources.

Direct Flow (also Direct Right)

Water diverted from a river or stream for use without interruption between diversion and use except for incidental purposes, such as settling or filtration.

Diversion

The removal of water from its natural course or location, or controlling water in its natural course or location by means of a ditch, canal, flume, reservoir, bypass, pipeline, conduit, well, pump or other device.

Drought

A long period of below-average precipitation.

Due Diligence

The actions made to complete a conditional water appropriation that demonstrate good faith effort toward putting a water right to beneficial use within a reasonable time period.

Effluent

Water discharged after use, such as water leaving a waste water treatment plant.

Effluent Exchange

The practice of using waste water effluent from trans-basin water, non-tributary water sources, or other sources without causing injury to other water rights as a replacement source of water. Utilizing this effluent exchange for replacement may allow diversion of water farther upstream that would otherwise have been out of priority.

Endangered Species Act

The federal law that governs how animal and plant species whose populations are dangerously in decline or close to extinction will be protected and recovered. The law protects not only threatened and endangered species, but also the ecosystems and habitat upon which they depend.

Energy Policy Act (EPACT)

A 1992 federal law that states, among other things, that no toilet for household use manufactured after Jan. 1, 1994, shall use more than 1.6 gallons per flush and that shower heads and faucets manufactured after Jan. 1, 1994, may not use more than 2.5 gallons per minute.

Exchange

A process by which water, under certain conditions, may be diverted out of priority at one point by replacing it with an equal quantity of water at another point.

Firm Annual Yield

The yearly quantity of water that can be dependably supplied from the raw water sources of a given water supply system.

Futile Call

A situation in which a junior (more recent) priority is allowed to continue to divert in spite of a downstream senior call because curtailing the junior right would not reasonably produce any additional water for the senior.

Ground Water

Water found below the earth’s surface.

Hydrologic Cycle

The movement of water from the atmosphere to the earth and back again to the atmosphere. The three stages are precipitation, runoff or infiltration and evaporation.

Instream Flows

Water flowing in its natural stream bed, such as water required for maintaining flowing streams or for fish. See also the Colorado Water Conservation Board.

Interstate Compacts

See, Compact.

Junior Rights

Water rights that are more recently established than older or more senior rights. Junior rights may not have the right to divert if their diversion causes a senior user to lack the full beneficial use decreed to the senior water right.

National Environmental Policy Act (NEPA)

The federal law enacted to ensure the integration of natural and social sciences and environmental design in planning and decision-making for projects that may impact the quality of the human environment.

National Pollution Discharge Elimination System (NPDES) Permit

A permit required under Section 401 of the Clean Water Act regulating discharge of pollutants to the nation’s waterways.

Non-Consumptive Use

Water diverted for use that is not consumed or permanently removed from the river system. For example, water withdrawn for purposes such as hydropower generation is returned to the river. It also includes uses such as boating or fishing where the water is still available for other uses at the same site.

Non-Point Source

A discharge that is distributed over a wide land area, not from one specific location. Runoff from city streets, parking lots, home lawns, agricultural land, individual septic systems and construction sites that finds its way into lakes and stream is generally considered a non-point source of pollution.

Point Source

Discharge from any identifiable point, including pipes, ditches, channels, sewers, tunnels and containers of various types.

Potable

Water that is considered safe for domestic consumption; drinkable.

Prior Appropriation Doctrine

A legal concept in which the first person to appropriate water and apply it to a beneficial use has the first right to use that amount of water from that source. Each successive appropriator may only take a share of the water remaining after all senior water rights are satisfied. This is the historical basis for Colorado water law and is sometimes known as the Colorado Doctrine or the principle of “first in time, first in right.”

Priority

The right of an earlier (senior) appropriator to divert from a natural stream in preference to a later (junior) appropriator.

Priority Date

The date of establishment of a water right. The rights established by application have the application date as the date of priority.

Raw Water

Untreated water.

Re-use

To use again, to intercept for subsequent beneficial use–either directly or by exchange–water that would otherwise return to the stream system.

Reservoir

An impoundment of collected water controlled by a dam or storage tank. Return Flows The unused portion of water that returns to a stream or river after a beneficial use.

Runoff

Water that flows on the earth’s surface to streams, rivers, lakes, and oceans.

Safe Drinking Water Act (SDWA)

Federal legislation that regulates the treatment of water for human consumption. Requires testing for and elimination of contaminants to levels for the protection of human health.

Senior Right

Water rights that are decreed earliest in priority by the water court.

Surface Water

Water present on the earth’s surface; streams, lakes, and ponds.

System Loss

An amount of water, expressed as a percentage, lost from a water storage or distribution system due to leaks, evaporation, seepage and unauthorized use.

Trans-basin Diversion

The conveyance of water from its natural drainage basin into another basin for beneficial use.

Trans-Mountain Diversion

The conveyance of water from one drainage basin to another across the Continental Divide.

Treated Water

Water that has been filtered and/or disinfected; sometimes used interchangeably with “potable” water.

Tributary

A stream or river that flows into a larger one.

Tributary Drainage

The area from which water naturally drains by gravity into a water course.

Tributary Ground Water

The area from which water naturally drains by gravity into a water course.

Urban Runoff

Excess water that doesn’t infiltrate into the soil, but flows to a storm sewer or open waterway.

Water & Sanitation District

A special taxing district formed by the residents of the district for the combined purpose of providing potable water and sanitary waste water services.

Water Right

A property right to make specific beneficial use of a particular amount of water with a specified priority date.

Watershed

An area from which water drains to a given stream or river or river system.

Wellhead Protection Program

An amendment to the federal Safe Drinking Water Act in 1986. Initiated to minimize the potential for contamination of public ground water supplies.

Wetlands

Areas with standing water of a high water table either permanently or for some significant period each year. Generally includes swamps, marshes, bogs and areas with water-loving vegetation that grows in or around water.

Xeriscape

A landscape concept to describe beautiful landscaping that has low water needs. The term was developed by Denver Water in 1981. It is derived from the Greek word xeros, meaning dry.