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Questions About the Project

+ Why was the project needed?

Woodland and Davis were two of only a very few cities in California that still relied entirely on groundwater for water supplies. In the past, groundwater was plentiful enough to meet community needs, and also state and federal water quality regulations. By itself, it was not expected that groundwater would be able to meet future state drinking water quality and wastewater discharge regulations. The quality of local groundwater supplies was deteriorating and had an increasing amount of salts and other minerals that threatened the environment and public health. The Cities determined they could not meet anticipated future regulations for the water coming into homes, or for water returned to the environment after leaving the wastewater treatment facilities, using groundwater only. An alternative, high-quality water source was needed to largely replace and supplement the groundwater supplies.

+ What are the benefits of the project?

The many benefits include health and safety of drinking water supplies, reduced costs from avoidance of wear and tear on water using appliances, compliance with treated wastewater discharge requirements, and environmental benefits associated with improvements to discharged wastewater and with the replacement of an antiquated intake on the Sacramento River with an intake with state-of-the-art fish screens. Resulting improvements in the quality of treated wastewater increase the opportunity for water reuse, advance environmental stewardship in the Yolo Bypass, and potentially lower wastewater treatment costs from what they otherwise would be in the future. Additionally, aquifer storage and recovery wells have been constructed in Woodland, which involves injecting high-quality, treated surface water into wells for later use. This allows Woodland to maximize the use of surface water supplies by storing the surface water in the ground during the winter months when more water is available, and delivering that water to customers during summer months and other dry times when surface water supplies are not as readily available.

+ Why couldn’t we continue to use groundwater as our sole water source? Isn’t there plenty of groundwater?

It’s the quality of the water – not the quantity – that prompted the shift from groundwater to surface water. It was getting more and more difficult to meet demands for water use and water quality regulations using existing infrastructure. A number of groundwater wells in Davis and Woodland were shut down and destroyed because they no longer worked and couldn’t be fixed, or because they exceed drinking water quality limits for nitrates and hexavalent chromium. Even with major improvements to groundwater facilities (wells and pumps, for example), the Cities would still fall short of meeting future water quality regulations for drinking water and treated wastewater. In short, the Cities needed a higher-quality source of water.

+ How much is an acre-foot of water, and how does it compare to how much water I use?

An acre-foot of water – a common unit of measure for water – is about 325,000 gallons. That’s roughly the amount of water used by two households in a year, including landscape water use.

+ How much water are we allowed through our water right permits?

WDCWA’s water right permit authorizes it to utilize up to 45,000 acre feet of water per year. However, diversions will be limited during summer months and other dry periods. During these times, WDCWA will utilize up to 10,000 acre feet of water under a senior water right purchased from the Conaway Preservation Group (see below).

+ What will happen in the summer months, when surface water under the project’s new water-right permits will not be available?

WDCWA purchased a senior water right for 10,000 acre feet of surface water from the Conaway Preservation Group. This water is subject to fewer restrictions between April and October and will be used during times when water under the primary water right is not available. Existing groundwater sources will continue to be used along with higher-quality groundwater from the deep aquifer to help meet peak summer demands. Combined use of surface and groundwater sources, referred to as “conjunctive use,” and the blending of supplies will result in substantial year-round improvements in water quality, including the summer months.

+ Does the treated water contain fluoride?

No, fluoride is not added to water supplies.


Questions About the Introduction of Surface Water to the Cities of Woodland and Davis

1 How is the surface water treated?

The surface water is treated in a new state-of-the-art Regional Water Treatment Facility designed to provide 30 million gallons of high‐quality drinking water per day under a variety of Sacramento River water conditions, including varying river levels and turbidity spikes. The facility includes proven treatment technologies used at nearby plants such as West Sacramento’s, including flash mixing, sand ballasted clarification, ozonation, granular media filtration and chlorine addition for disinfection. It is designed to meet or exceed current and potential future drinking water regulations.

2 What testing is done to test for contaminants?

Drinking water quality standards in California are established by the Federal government under the Environmental Protection Agency (USEPA) and the State Water Resources Control Board (SWRCB). To ensure the safety of drinking water, the WDCWA and Cities are required by the California Division of Drinking Water (DDW) to take samples regularly and test them for a multitude of compounds to ensure they meet drinking water quality standards. Samples are taken both at the connection points between the WDCWA pipelines and the Cities distribution systems and also within the Cities at locations agreed to by DDW. WDCWA is requiring that the Regional Water Treatment Facility produce high quality water that will exceed current drinking water standards.

Each year, the Cities each send out a water quality report that details the results of ongoing water quality testing. If for any reason your drinking water does not meet state or federal water quality standards at any time during the year, you will promptly receive a notice from your City detailing any precautions you should take before using the water.

3 How do I report problems?

If for any reason you believe your water quality is in question, please contact your City immediately as follows:

City of Davis water users: Call Public Works at (530) 757-5686. The City requests water users call to report water quality problems so they can be quickly addressed. Please do not email to report water quality concerns.

City of Woodland water users: Please call 530-661-5962 (7 a.m. – 4 p.m., Monday-Friday). After hours, the call will roll over to Yolo County Communications, which is available 24 hours per day, 7 days per week. Water users may also email Public Works at [pubworks@cityofwoodland.org][5], or submit a report through the “myWoodland” mobile app.

4 Do I need a water filter?

Most people will not need to use a water filter. A water filter can provide additional protections for people with severely compromised immune systems.

5 Do I need a water softener?

Surface water is naturally much softer than groundwater, so a water softener in most cases will likely not be necessary. Water hardness is expected to be reduced by approximately 80 percent. Additionally, removing water softeners will improve the quality of treated wastewater discharges to the environment. Water softeners add salts to wastewater discharge and ultimately impact the cities’ ability to meet state and federal wastewater quality discharge requirements. If you choose to continue to use a water softener, please contact your service provider to ensure it is programmed properly for reduced water hardness.

6 I have a severely compromised immune system. Is tap water safe for me?

Consult with your doctor about additional protections that may be required for those with severely compromised immune systems, such as in-home filtration units.

7 Can I still use tap water for my fish aquarium?

Tap water should be specially treated for use in aquariums. Check with your local pet supply store for recommendations.

8 Are there chloramines in my drinking water?

No. Currently, finished water from the new treatment plant is designed to add chlorine, not chloramines, based on the needs of each City. Chlorine will be added to meet the minimum chlorine residual required by the Division of Drinking Water (DDW) to ensure that the distribution system is clear of harmful bacteria. Finished water chemicals (sodium hypochlorite, sodium hydroxide, orthophosphate corrosion inhibitor and phosphoric acid) can be added at the Regional Water Treatment Facility to the pipelines delivering treated surface water to Woodland and Davis. Each City has the ability to select individual values for finished water pH, chlorine residual, orthophosphate corrosion inhibitor, and phosphorous residual to be served to its distribution system.

9 What is zinc orthophosphate?

Zinc Orthophosphate (ZO) is used as a corrosion inhibitor against the release of iron, copper, and lead into our drinking water distribution system. ZO has successfully been used as a dissolved metals inhibitor in municipal water systems for more than 50 years. The US Environmental Protection Agency (USEPA) identified ZO as one of the best available technologies to minimize leaching of metals into drinking water. The Cities have begun injecting very low levels of ZO to ensure a smooth transition to surface water. The new Regional Water Treatment Facility will continue to inject ZO to prevent corrosion in the future.

ZO works by creating/coating a film or scale barrier on the inside of the distribution pipe and trapping the underlying metals below. The control of this microscopic scale in an existing water system is one of the primary factors in maintaining water quality that is low or free from excessive dissolved metals.

ZO’s use is well known, reliable, and safe. It has been recommended for use in drinking water by American National Standards Institute/National Sanitation Foundation (ANSI/NSF) Standard #60 Drinking Water Treatment Chemicals, and has been widely approved for use in potable water systems by the State Division of Drinking Water (DDW). Proper use of ZO easily adapts to existing and changing water conditions without changing water chemistry or taste.