Nevada water rights
Recently, there has been a lot of discussion about surface water rights and groundwater rights.
This discussion has been exasperated by the fact that surface water flow of the Humboldt River at Battle Mountain on April 29, 2022 was measured at 79.7 cubic feet per second (ft3/sec.) and the flow of the river at Comus was at 54.5 ft3/sec.
However, the river flow at Imlay was 15.1 ft3/sec. and only 0.29 ft3/sec. at the upper end of the Rye Patch Reservoir.
It should also be noted that a United States Geological Survey (USGS) study has documented that over pumping of groundwater is affecting the surface water flow in the middle and lower reaches of the Humboldt River Basin (https://www.usgs.gov/centers/nevada-water-science-center/science/evaluation-streamflow-depletion-related-groundwater).
In order to help readers understand how over utilization of groundwater affects surface water flow, we need to understand how they are connected.
Groundwater and surface water are essentially one resource, physically connected by the hydrologic cycle.
Although water law and water policy often consider groundwater and surface water as separate resources, groundwater and surface water are functionally inter-dependent.
Groundwater and surface water interactions are controlled by their hydraulic connection.
If the groundwater table is in physical contact with the stream bed, it is a hydraulically “connected” system.
The exchange of water between the groundwater system and a stream is controlled by the difference in elevation between groundwater table and the water level in the stream.
Under natural conditions, prior to the pumping of groundwater from wells, streams are the primary discharge outlet for groundwater: rainfall percolates into the ground and recharges the groundwater system, and then water flows very slowly through the groundwater system, eventually discharging to streams.
Groundwater discharge to streams provides the base flow of streams and is often a primary component of the total streamflow.
When groundwater wells are developed, pumping captures water that would otherwise discharge to streams, which decreases the base flow to the streams. This decrease in groundwater discharge to streams, caused by pumping, is called stream depletion.
So, the question is, “How do surface water rights and groundwater rights interact?”
Nevada water law is based on two basic principles: prior appropriation and beneficial use. Prior appropriation – also known as “first in time, first in right” – allows for the orderly use of the state’s water resources by granting priority to senior water rights in times of shortage.
This concept ensures senior water users are protected, even as new uses for water are allocated. A water right permit may only be granted for beneficial uses as provided in chapters 533 and 534 of the Nevada Revised Statutes.
The State Engineer is the head of the Nevada Division of Water Resources, a division within the Nevada Department of Conservation and Natural Resources.
The State Engineer is responsible for administering and enforcing Nevada water law, which includes the appropriation of surface and ground water in the state, and the adjudication of pre-statutory vested water rights, dam safety, and other duties.
For groundwater allocation, the tern “Perennial Yield” is an important term to understand. Perennial yield is the maximum amount of groundwater that can be salvaged each year over the long term without depleting the groundwater reservoir. The perennial yield cannot be more than the natural recharge of the groundwater reservoir and is usually limited to the maximum amount of natural discharge.
Approximately 45 basins in Nevada are over-appropriated; this means that more groundwater is allocated for use than is available. There is a historical reason for why these basins are considered over-appropriated. Some were already over-appropriated prior to the perennial yield being known. New data changed the perennial yield in some basins, which meant that the basins ‘became’ over-appropriated.
What can be done? The State Engineer’s Office is using a range of management tools to bring groundwater systems back into balance. These include:
• Grant changes of irrigation rights for consumptive portion only
• Cancel water rights for failure to show due diligence
• Forfeit unused certificated rights
• Deny all extension of time requests and call for proofs of beneficial use
• Substitutive uses in the case of mine dewatering
• Exchange of treated effluent for potable water
• Conjunctive use of all sources
• Regulate by priority
Due to the limits of space, I will provide information on how Nevada water rights laws differ between surface water rights and groundwater rights in my next article.
For more information on this topic, you can go to: http://dcnr.nv.gov/documents/documents/nevada-water-law-101/