Fourth year of drought brings extreme limits to water supply

The U.S.  Bureau of Reclamation asks Central Valley Project water contractors to plan for extremely limited water supply conditions after the new year

SACRAMENTO, CALIF. – As California is preparing for their fourth year of drought, the Bureau of Reclamation warns Central Valley Project water contractors of lessened water allocations.

Two months after the start of the new water year on Oct. 1, the Shasta Reservoir, the state’s largest reservoir and cornerstone of the Central Valley Project (CVP), is currently at 31% capacity. With the reservoir being so low, the Bureau of Reclamation is asking its contractors who are receiving water from the CVP for municipal and industrial use to begin planning for “potentially extremely limited water supply conditions” after the start of the new year.  

As a result of the severity of the drought and with water storage reservoirs near historic lows, under Reclamation’s Municipal and Industrial (M&I) Water Shortage Policy (WSP), the CVP’s M&I contractors are asked to provide specific formulas to calculate public health and safety numbers. The formula is the addition of domestic, commercial/institutional and industrial usage as well as system losses together. Evaluation of the numbers will help determine the amount of water considered necessary for public health and safety (PHS) for each area.

With the drought continuing, it will be increasingly more difficult, if not impossible for the bureau to meet the competing needs for water. Unfortunately drought conditions continue in California despite storms experienced earlier this month. 

Conservative planning efforts will help better manage the limited water resources in the event conditions remain dry and the state moves into a fourth consecutive drought year. As a result the bureau will need to begin implementation of additional and more severe water conservation actions for the CVP. This is where the M&I WSP throughout the CVP comes into play.

The Bureau of Reclamation created the M&I WSP to help define water shortage terms and conditions for applicable CVP contractors. The policy primarily focuses on the administrative process and calculations of public health and safety (PHS) and possible adjustments to a contractor’s historical use. The guidelines are intended to be objective and clear to allow CVP contractors to know when, and by how much water deliveries may be reduced by water supply conditions or in this case the drought. 

Provided there is CVP water available, the bureau will strive to deliver CVP water to M&I water service contractors at no less than the amount needed to meet PHS needs if there is in fact a state of emergency declared. 

In order to determine the amount each contractor needs to sustain PHS needs, the M&I WSP uses an equation. The equation is the addition of the amount of domestic usage (D), commercial and institutional usage (CI), industrial usage (I) and system (conveyance) losses (L) together. Domestic use is the total of the current population times 55 gallons per capita per day; commercial and institutional is 70% of projected commercial demand; industrial is 70% of projected industrial demand; and system (conveyance) losses (L) is equivalent to 10%. 

According to the bureau, based on the severity of the condition of shortage, reclamation may adjust the CI, and I percentages of demands to ensure domestic use needs are met. 

For those who have a separate contract or a combined contract for irrigation purposes goes through a similar project with a separate equation. Before any allocation of M&I water is reduced, allocation of irrigation water will be reduced below 75% of the contractors contract total. 

The bureau continues to closely monitor hydrologic conditions and will provide regular updates in the coming months. Initial water supply allocations for the Central Valley Project will be announced in February.

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