Surface Water Curtailment for the State of California – Important Notice to Laboratories and Users with Special Equipment

On April 29, 2021, the State of California Department of Water Resources enacted Term 91, which is a water curtailment protocol to avoid diversion of surface water in seasonably dry conditions. In addition, due to low reservoir inflow, the Bureau of Reclamation designated 2021 a Shasta Critical Year which further reduces the amount of surface water available. Since July 2017, the University has supplied the campus domestic (drinking) water system with both groundwater from on-campus wells and surface water from the Sacramento River treated by the Woodland Davis Clean Water Agency (WDCWA) in partnership with the Cities of Woodland and Davis.  Term 91/Shasta Critical curtailment reduces the amount of surface water that can be diverted but does not curtail the groundwater sources.  On any given day, the University will use a number of water supply sources to meet the campus domestic water demand.  During normal conditions, surface water comprises approximately 85-90% of the daily campus demands; during Term 91 curtailment conditions this drops to below 50%. During a dual Term 91 and Shasta Critical Year curtailment, surface water will comprise approximately 25% of the daily campus demands. Term 91/Shasta Critical curtailment will reduce the amount of available surface water, likely through October 31, 2021 or later. Prior to 2021, Term 91 curtailment was enacted in 2018 and 2020. No water shortages were experienced by the campus in previous curtailment periods, nor are any shortages expected for this year’s Term 91/Shasta Critical curtailment.

Each source of domestic water has different water chemistry, which can vary over time.  Facilities Management’s Utilities division monitors specific water quality parameters at each source including the distribution system.  During curtailment, hardness and conductivity are two parameters that are regularly monitored and can be used as indicators for groundwater versus surface water make-up.  Hardness is a measure of the amount of dissolved minerals, typically calcium and magnesium.  While harder water does not cause adverse health effects, hard water can cause mineral deposits to accumulate in pipes and building equipment such as water heaters, dishwashers, and boilers.  Over time, the mineral deposits may cause clogs or other maintenance issues.  Conductivity is a measure of the ability of the water to conduct an electrical current.  This current is transported by dissolved ions in water; thus the conductivity increases as the amount of dissolved ions increases.  Typically water consumers do not prefer the taste of highly conductive waters, and because of this aesthetic reason the California State Water Resources Control Board, Division of Drinking Water suggests that water systems provide water with conductivity below 900 µS/cm. All of UC Davis’s water supplies are well below this recommended limit.

Facilities Management is aware of changes to the water chemistry and potential impacts to equipment, including water treatment systems that provide ultra-pure water or deionized water to campus laboratories. Maintenance will be adjusted as needed to ensure that users do not notice a change to the quality of water from these systems.

Equipment that is maintained by an individual department or outside vendor contracted by the department may require a more frequent preventative maintenance schedule to account for the changes to water chemistry.  The water chemistry may be, at times, comparable to the water chemistry that served campus prior to 2017 when surface water was added to the system.

To learn more about Term 91 visit: www.waterboards.ca.gov/waterrights/water_issues/programs/bay_delta/term_91