What could happen next?
There are no anticipated Colorado River reductions in water supply for Arizona in 2017. Reservoir storage in Lake Mead remains above shortage declaration levels. However, absent new actions and conservation, the outlook for future years show a probability of over 50% in 2018 of a shortage occurring on the system.
SRP reservoir levels on the Salt and Verde River system have held steady, are at storage levels above reductions in delivery, and are at a low probability of experiencing shortages in future years. SRP's water system is also comprised of an extensive network of groundwater wells. Conjunctive management of the surface water and groundwater systems have resulted in an extremely reliable water supply during this extensive dry period over the past 21 years.
Yet risks exist.
Colorado River shortage
Federal projections indicate there remains the probability of a shortage on the Colorado River over the next five years. Persistent drought and over allocation of the Colorado River’s water is causing water levels at Lake Mead to drop. Hydrologists have identified specific levels beyond which the health of the river and lake may be in crisis. The Arizona Department of Water Resources (ADWR), and the state’s largest Colorado River user, CAP, are taking steps to help ensure the lake’s long-term viability.
If a shortage is declared, CAP would be subject to reductions in Colorado River water because CAP holds a "junior" priority water entitlement among the Lower Basin states.
A near-term shortage would not, however, impact water supplies for Arizona's cities, towns, industries, mines or tribes using CAP water.
It would halt water deliveries for recharge and reduce a portion of the CAP water supply identified for groundwater replenishment, would impact agricultural users in central Arizona and cause an increase in CAP water rates.
Farmers in central Arizona may choose to offset supply reductions in their CAP supply by using local supplies, including pumping groundwater. If more severe shortages are declared and Arizona's supply of Colorado River water is reduced further, CAP, ADWR and the Arizona Water Banking Authority are developing plans to recover stored water and deliver these supplies should the need arise.
The Salt and Verde rivers systems and an extensive network of high-capacity groundwater wells have ensured SRP water supplies are resilient – able to meet customers’ water demand throughout SRP’s 100-year history and meet future demand as well. A reduction in the water allocation has been declared only twice, from 1950-1951 and, most recently, from 2003-2004.
Current conditions are such that SRP does not anticipate any reductions in delivery. SRP operates its water system each year as if the system is entering into a drought of record. This conservative approach to managing the reservoir and groundwater system has proven very effective in ensuring water allocations are not reduced.
In the instance of a shortage of stored water in SRP's reservoirs, SRP would reduce allocations to its customers, maximize the use of the groundwater wells, and exercise a dry year water lease option with the Gila River Indian Community to access a portion of the tribe's Colorado River water and have that water delivered through an interconnect system that links to the CAP canal.
What you should know
It is precisely because of the redundancy in water supply from CAP and SRP, a commitment to water conservation by water customers, and advanced planning that Greater Phoenix is so well-positioned to weather extended dry periods and droughts.
Here's what you should know now:
- Careful and proactive water management by both CAP and SRP has ensured Greater Phoenix has an adequate water supply to meet current and future demand.
- The SRP system has proven resilient, falling into shortage stages only twice during its 110-year history.
- SRP water deliveries have declined by approximately 20% over the past 15 years due to changing water use patterns and customer conservation efforts.
- SRP has initiated innovative water resource partnerships and continues to make additional investments in water infrastructure that further enhances supply reliability for its customers and regional partners.
- CAP is prepared for potential shortages on the Colorado River.
- Dropping levels in Lake Mead could seriously impact power generation and Arizona's water supply.
- CAP and ADWR are working diligently to protect levels in Lake Mead by negotiating the Drought Contingency Proposal (DCP) to improve the overall health of the river system while honoring all previous agreements.
- CAP will continue to take proactive steps to improve the long-term health of the river system in collaboration with the State of Arizona, CAP water customers, the Colorado River Basin states, the federal government, Mexico and other local and regional partners.
- You can help by educating yourself about your water supply, learning how you can conserve or improve water efficiency in your home or business and supporting the regional conservation plans, including those for the Colorado River.