Water Rights for a Mine and the Problem of Dewatering
A mine consumes water to process ore and removes water simply to keep the workings open. Western water law was built around the first and has had to be stretched around the second, which is why dewatering produces more disputes than supply ever does.
The rule in short
In the western states a mine holds water under an appropriative right defined by priority, quantity and beneficial use, obtained by permit from the state water agency. Removing groundwater to keep workings dry is itself a use of water in most of those states and requires its own authorization. Drawdown that reaches senior wells, springs and streams creates liability under state law, and the water removed cannot be discharged or reinjected without federal and state permits.
Mining and water law grew up together. The appropriation doctrine that governs most of the western states came out of the diggings, where miners settled competing demands on a creek by the rule that the first to put water to use held the better right. Congress later confirmed those arrangements. The irony is that the industry which produced the doctrine now spends more of its legal effort on getting rid of water than on obtaining it.
The right a mine actually holds
East of roughly the hundredth meridian, water rights follow land ownership along a watercourse, and a riparian owner may make reasonable use of the stream. West of it, and in the hybrid states in between, water is appropriated: a user obtains a right by applying to the state agency, diverting water and putting it to beneficial use, and the right is defined by a quantity, a point of diversion, a purpose and a date of priority.
Priority does the work. In a shortage the senior right is satisfied in full before the junior receives anything, rather than everyone taking a proportional cut. A mine with a recent priority in an over-appropriated basin holds a right that is legally sound and practically worthless in a dry year, which is why acquisition of senior agricultural rights, and their transfer to mining use, is a routine part of project development. Transfers require a change application, and the test is whether other appropriators would be injured by the new pattern of use.
Why removing water counts as using it
An open pit or an underground working driven below the water table fills. Keeping it dry means pumping continuously, often at rates far exceeding anything the process plant consumes. The operator does not want the water and would happily leave it in the ground.
State law nonetheless treats the removal as an appropriation in most western jurisdictions, and for a sound reason: the effect on the aquifer is identical whether the pumper wants the water or not. The consequence is that a mine needs authorization to dewater, needs a place to put what it removes, and acquires an appropriative right in the removed water that it may be able to use, sell or exchange. Some states handle this with a dedicated dewatering permit; others fit it into the ordinary groundwater permit with conditions attached.
Drawdown and the neighbors
Sustained pumping creates a cone of depression that expands outward for as long as the pumping continues, and in a low-permeability setting it can reach miles. Wells within it lose yield, springs at the margin dry up, and streams that gained flow from groundwater begin to lose it.
The legal responses vary. Some states apply strict priority to groundwater, so a senior well owner may compel curtailment. Others apply a reasonable use standard, and still others require the pumper to make the affected user whole by deepening the well or supplying replacement water. What is common everywhere is that the obligation is now written into the permit rather than left to a lawsuit: monitoring networks, trigger levels, and a mitigation plan the operator must execute when a trigger is hit. Effects on surface flows are analyzed as part of the federal environmental review of a plan of operations, so the state water proceeding and the federal permitting proceeding examine the same hydrology on different schedules.
Two entirely separate authorizations are involved and they are issued by different bodies under different statutes. The state agency decides whether water may be removed from the aquifer. The discharge permit decides whether the water removed may enter a stream and on what terms. An operator holding the first and lacking the second must store or reinject everything it pumps.
Where the water goes
Water leaving the mine has four possible destinations, and each carries a different authorization.
| Destination | Authorization required | Principal constraint | Post-closure exposure |
|---|---|---|---|
| Discharge to a stream | Federal discharge permit with state certification | Effluent limits and water quality standards | Treatment may be needed indefinitely |
| Reinjection to the aquifer | Underground injection authorization | Protection of underground sources of drinking water | Monitoring obligations continue |
| Beneficial use by others | State change application and delivery agreement | No injury to other appropriators | The right lapses if use stops |
| Storage and evaporation | State approval of the impoundment | Seepage control and wildlife protection | The impoundment is a reclamation liability |
Reinjection is attractive because it returns water to the basin and dampens drawdown, but injected water must not degrade a drinking water source, and mine water often carries the metals and salinity that make that showing difficult. Discharge is administratively simpler and substantively harder, because the limits are set to protect the receiving water rather than to accommodate the mine.
The pit lake and what outlasts the mine
When pumping stops, the water table rebounds and an open pit below it becomes a lake. In arid basins that lake evaporates continuously, drawing water toward it in perpetuity. Regulators in several states have concluded that this is a consumptive use requiring its own water right, held forever, which converts a closure feature into a permanent appropriation that must be acquired and dedicated.
Water chemistry compounds it. A pit lake concentrating dissolved metals through evaporation may exceed standards for wildlife and for any use downgradient, and the response — treatment, backfilling, or a permanent right and monitoring commitment — is negotiated as part of closure planning rather than at the end of it. These commitments are secured through the same financial assurance machinery described in reclamation permitting and bond release, and where the obligations were never funded the result is the problem set out in abandoned mine liability and the Good Samaritan question. On or near a reservation, the additional question of who may regulate a non-member operator's effect on tribal water runs through the limits on tribal civil authority over non-members, and it is answered before the state permit is worth anything. Even the underlying mineral tenure is unaffected by all of this: a valid mining claim conveys no water at all.
Points to carry away
- Western mine water is held under prior appropriation, where priority in time governs and a right is measured by beneficial use rather than by land ownership.
- Mining custom on the public domain produced the appropriation doctrine, and Congress confirmed those vested rights by statute.
- Dewatering is treated in most western states as an appropriation requiring its own permit, even though the operator wants the water gone.
- Drawdown from sustained pumping can reach senior wells and springs, and mitigation obligations are commonly imposed as permit conditions.
- Discharging mine water to surface waters requires a federal pollutant discharge permit, and reinjecting it requires an underground injection authorization.
- A pit lake that continues to evaporate after closure represents a consumptive use that outlasts the mine.
Questions readers ask
Is water pumped from a pit owned by the mine that pumped it?
Not in the sense of ownership in an object. In an appropriation state the operator holds a right to a quantity of water for a stated purpose with a priority, and the water itself remains a public resource. That distinction matters when the operator wants to sell surplus dewatering flows to a municipality or a farmer, because the transfer requires a change application testing whether other appropriators would be injured. Water that leaves the mine on those terms is moving under a modified right, not being sold as property.
Do federal reserved rights affect a mine's supply?
They can, decisively. When the United States reserves land for a reservation, a park or another federal purpose, it implicitly reserves water sufficient to accomplish that purpose, with a priority dating from the reservation rather than from any diversion. Those rights are frequently senior to everything a mining company holds and are often unquantified until a general adjudication resolves them. A project drawing from a basin with unquantified reserved claims is planning against an unknown senior demand, which is a supply risk rather than a permitting one.
What happens to mine water obligations after closure?
They rarely end. Workings that filled during operation continue to produce water, and treatment systems built to meet discharge limits may need to run indefinitely. Regulators respond by requiring long-term funding assurances covering post-closure treatment, separate from the reclamation guarantee for earthwork. The operator's water rights also need attention at closure, because a right not exercised for the statutory period can be forfeited under state abandonment rules, and a company that stops pumping may lose the priority it will want if operations resume.
Sources
- Cornell Legal Information Institute — 30 U.S.C. 51, Vested Water Rights RecognizedCongressional recognition of water rights acquired by priority of possession under local custom.
- Cornell Legal Information Institute — 33 U.S.C. 1342, National Pollutant Discharge Elimination SystemThe permit required before mine water is discharged to waters of the United States.
- Cornell Legal Information Institute — 33 U.S.C. 1341, State Water Quality CertificationThe state certification a federal license or permit affecting discharges requires.
- Cornell Legal Information Institute — 42 U.S.C. 300h, Underground Injection ControlThe program governing reinjection of water into the subsurface.
- Cornell Legal Information Institute — 30 U.S.C. 1265, Environmental Protection Performance StandardsRequires coal operations to minimize disturbance to the hydrologic balance.
- United States Geological Survey — Water ResourcesFederal hydrologic data and groundwater monitoring used in drawdown analysis.
- Cornell Legal Information Institute — 43 CFR Part 3809, Surface ManagementRequires plans of operations to address water quality and reclamation of water resources.
Justice Partners Journal is a publication, not a law firm. This article states general rules and cites its sources; it is not advice about any particular case, and the law differs by state and changes over time.
