Skip to main content

Water Resources

The Water Resources Division manages, develops and administers ongoing programs in areas such as: watershed management, groundwater recharge, water resources planning, sampling and water quality testing and reporting, management of the permits, assisting operations in reviewing reports to the state and federal water and sewer agencies, procedures and protocol development for lab work, developing, modifying and implementing the pretreatment program and assisting in grants and loans. The Water Resources Division also oversees EVMWD’s laboratory that provides test results for water and wastewater samples collected at EVMWD’s treatment, distribution, and collection systems.  The Water Resources Division is organized in three sections:

  • Water Resources Planning
  • Water Systems Engineering
    • Water Protection
    • Recycled Water
    • Laboratory and Water Quality
  • Wastewater System Protection

Water Sources

EVMWD’s water supply is a blend of local groundwater, surface water from Railroad Canyon Reservoir (Canyon Lake), and imported water. On average, 65% of our supply is imported. Annual water production in the Elsinore Division is about 27,000 acre-feet.


The Elsinore division has 14 active municipal wells that provide quality drinking water from 35% of our groundwater wells. Several additional wells are planned. Groundwater is disinfected with chlorine and chloramines at the wellhead and represents 40-50% percent of drinking water supplies in the Elsinore division. By early 2005 all water supplies to the Elsinore Division will be disinfected by chloramines, which is a disinfectant commonly used in the United States. For more information, view the Consumer Confidence Report, section 2, Water Contaminants and Your Health.

Temescal Division 

EVMWD’s Temescal Division was acquired in 1989 when the district purchased the Temescal Water Company. Residential customers are served from domestic wells in the Coldwater Basin. Domestic water supply is also supplemented by imported water from Lee Lake Water District. Agricultural customers in the Temescal Valley receive water from several wells in the Bunker Hill, Colton and Temescal Valley basins, and surface water from Lee Lake, which is fed by the Temescal Wash. Annual water production for this division ranges from approximately 6,000 to 7,000 acre-feet.

Railroad Canyon Reservoir 

EVMWD owns Railroad Canyon Reservoir, also known as Canyon Lake. The reservoir impounds local runoff from the 750 square mile San Jacinto River watershed. Canyon Lake holds nearly 12,000 acre-feet of water behind Railroad Canyon Dam.

Imported Water 

The Colorado River Aqueduct and State Water Project provide most of southern California’s water supply. EVMWD imports treated, disinfected water from Lake Skinner and Lake Mathews, located in Temecula and Riverside respectively. Both treatment facilities are operated by the Metropolitan Water District of Southern California (MWD). On average, imported water accounts for 65% of EVMWD’s supply.

Water Management Goals 

EVMWD has a comprehensive water supply master plan to enable the District to:

  • Meet future water quality standards
  • Optimize MWD supply and pricing
  • Promote reclamation
  • Improve service to older areas as necessary
  • Improve taste

Recycled Water

Water recycling extends the Southland’s imported supplies and ensures that we will have reliable water sources for the future. Recycling is good for the environment because it makes good use of scarce resources. It’s also the right thing to do. Most of us recycle our newspapers and aluminum cans, why not our water?

Recent dry years and droughts have sparked interest in the need to recycle water as a cost-effective way of sustaining water resources. Water recycling follows nature’s lead in treating water so that it can be used for agricultural, commercial and landscape irrigation. Recycling or reclamation provides a stable source of water that can offset future dry spells while shoring up the reliability of Southern California’s water supply.

Fact Sheets and Best Practices Management
EVMWD Recycled Water Fact Sheet
EVMWD Recycled Water Fact Sheet: Wildomar/Summerly Service Area
EVMWD’s Best Practices Management for Recycled Water

Frequently Asked Questions

Is recycled water safe?
Yes. After the extensive treatment process, recycled water is clean and safe to irrigate playgrounds, other outdoor recreation areas, selected crops, pastures and many other uses. The processed water is clear and odorless as it flows out of reclamation plants, into streams and, eventually, to the ocean.

How is wastewater treated?
Reclamation plants follow and enhance the recycling process that occurs in nature by simulating the filtration, decomposition and disinfection processes that occur underground. Wastewater plants use settling, biodegradation, and disinfection to make the water safe for discharge into the ocean. All reclaimed water receives these initial layers of treatment, plus additional treatment needed to protect our freshwater lakes, streams, and groundwater basins.

Taking cues from nature
All water is recycled in nature. Every drop is part of the natural cycle of evaporation, rainfall or snowfall, and run-off flowing to the ocean. When Mother Nature treats water, sunlight kills pathogens, plants trap solids and adds oxygen, and beneficial bacteria “clean” the water, which then seeps through the soil, further filtering it. Reclamation and recycling follows nature’s example in purifying water, but accelerates the process with chlorination and filtering to remove dissolved salts and other impurities. By taking advantage of how nature has always purified water, reclamation and recycling provide a reliable and safe source of water for the region.

Who uses recycled water?
California is a national leader in water recycling research and has developed progressive policies that promote water recycling and reuse. Recycled water keeps schools, nurseries, parks and roadside greenbelts looking sharp. It is also used for groundwater recharge and industrial uses such as snowmaking, cooling machinery, firefighting, and street cleaning.

What is EVMWD doing with recycled water?
Recycled water begins as wastewater from our homes and businesses. It is then treated, filtered and disinfected, often discharged into a water body such as a river, stream or ocean. EVMWD however, provides an additional level of treatment, called “tertiary” treatment which uses a state-of-the-art ultraviolet system to remove 99.9 percent of pathogens. “Tertiary” treated water is so highly cleaned that it is safe for human contact, and more than 27,000 acre-feet of recycled water are used throughout Riverside County each year. An acre-foot is approximately 326,000 gallons of water, enough water for two average families for one year. Recycled water uses include irrigating crops, golf courses, fishing lakes, landscape irrigation and wetlands enhancement.

Recycled water is an affordable and reliable resource and will play a significant role in Lake Elsinore’s future. Long plagued with severe seasonal evaporation losses, Lake Elsinore is a natural recreational lake that annually loses 14,000-acre feet of water to evaporation. In January 2002, the Regional Water Quality Control Board granted EVMWD a permit to discharge recycled water via its Regional Wastewater Treatment Plant into Lake Elsinore for two years under a pilot project to research the effects of recycled water on the lake—the treatment plant already discharges four million gallons of tertiary treated water a day into the Temescal Creek. On June 28, 2002, members of the Recycled Water Task Force, the EVMWD Board of Directors and staff and Lake Elsinore City officials joined to celebrate the first release of recycled water into Lake Elsinore. This is the first time that recycled water has been released into a recreational lake in California. About 2,000-acre feet of recycled water is being released in the remaining six months of 2002.


Introduction to PFAS

What Are PFAS?
Per- and polyfluoroalkyl substances (PFAS) are a group of man-made chemicals, including PFOA, PFOS and GenX, which is a chemical replacement for PFOA. For more than 70 years, PFAS have been manufactured and used in variety of industries worldwide. According to the Environmental Protection Agency (EPA), exposure to certain PFAS can lead to adverse health effects in humans.

Where Are PFAS Found?
PFAS are man-made contaminants that are found in thousands of products that are used daily, including our shampoo, clothing, cleaning products, food wrappers, non-stick cookware, firefighting foam and carpet. Most people worldwide have measurable amounts of PFAS in their blood and are typically exposed to PFAS through eating food grown in contaminated water/soil or consuming food from packaging that contains PFAS; breathing air with dust particles from contaminated soil, upholstery, clothing; inhaling fabric sprays containing PFAS; or drinking contaminated water.

What is EVMWD Doing to Treat and Remove PFAS?
Our customers are our top priority, and EVMWD is closely monitoring PFAS in our water supply. Our water is thoroughly treated and tested thousands of times per year to ensure it meets water quality standards for state and federal regulations. If PFAS are discovered at a reportable level, EVMWD will take immediate and appropriate action to ensure water meets state and federal regulations.

In March 2020, PFAS were detected in Canyon Lake above State Response Levels and the water source was taken offline. Until its PFAS levels are treated and reduced, EVMWD is replacing this supply with imported water from Metropolitan Water District. EVMWD has evaluated multiple treatment alternatives to treat for PFAS in Canyon Lake. EVMWD is pursuing a hybrid Granular Activated Carbon and Ion Exchange (GAC/IX) treatment to lower levels of PFAS and address other water quality concerns including taste and odor. Pilot testing is anticipated to begin in early 2021.

Additional Resources:
PFAS Fact Sheet
PFAS Information

Line Flushing

Elsinore Valley Municipal Water District (EVMWD) routinely opens fire hydrants to blast stagnated water and sediment from local water mains. The presence of fine sediment in the water system poses no public health hazard. However, the accumulation of sediment may cause water to become discolored or develop an unpleasant taste and odor.

Routine flushing ensures EVMWD is delivering safe and high-quality household water that meets California’s strict quality standards, which are enforced by the California Department of Public Health. Regular clearing helps protect pipelines from blockages and corrosion. More than 8,100 fire hydrants and 747.5 miles of water pipelines (ranging in size from 4-inch to 42-inch) cover EVMWD’s 97-square-mile service area.

Every year, EVMWD personnel collect more than 17,000 routine water samples from the water lines to test for salts, metals and potential contaminants. Chlorine is neutralized from the water. This is recorded and reported to the local Regional Water Quality Control board which determines water discharge requirements.

When does flushing occur?

EVMWD field maintenance crews conduct their flushing program annually. This process requires crews to flush each hydrant or water line for approximately 1 minute, or 400 gallons of water, each time. Some “hot spots” are flushed as often as once a month to ensure EVMWD is delivering quality water to our customers.

What time of day will flushing occur?

Flushing can occur anytime we receive a water quality concern. Staff will investigate and, if it is determined flushing is needed, EVMWD personnel will flush the lines to improve the water quality.

How will the flushing affect me?

Try not to use water during flushing. If you do experience discolored water, stop using the water and open a hose bib as close to the meter as possible. This will minimize the amount of discolored water that enters your plumbing. Once the water is clear in the front hose bib, you can then open the faucets in the house to flush any remaining discolored water. The discolored water is not harmful but it is not recommended for human consumption. Your water service should not be interrupted. However, if you notice any difficulties with water flow, color or taste that do not resolve please notify EVMWD at the number listed below.

Isn’t line flushing a waste of water?

EVMWD is always mindful of the amount of water being used during the flushing program. Water flushed from the lines is not wasted. Instead, water is sent to the District’s sewer collection system, where it will be conveyed to one of the District’s three wastewater reclamation plants, treated to a level acceptable to the Water Resources Control Board and returned to our system as recycled water. If the collection system is not within reach, the flushed water will be collected at the local storm drain and diverted to one of our two lakes, Canyon Lake or Lake Elsinore.

For further questions or assistance, please call the District Operations Department at (951) 674-3146 ext. 8305.

Flushing Fact Sheet



EVMWD customers expect high quality water that is pure and healthful. Water purveyors spend millions of dollars to purify and treat water before it is delivered to consumers. However, many consumers are not aware that District personnel work diligently to protect potable water from pollution and contamination as it flows through the distribution system.

Cross-Connections and Backflow Prevention 

Unprotected cross-connections can pollute or contaminate potable water on a customer’s property or the distribution system from backflow. Examples of cross-connections are a water supply line connected to equipment containing a non-potable (unfit to drink) substance, or the end of a hose submerged in a bucket containing cleaning solution (photo).







Using a garden hose without backflow prevention can pollute or contaminate a water system from backsiphonage.

Backflow is a reversal in the normal flow of water within a potable water system. Water systems are designed to allow water to flow in one direction from sources, such as a treatment plant or well, to the points of use. Examples of points of use are landscape irrigation system, hose spigot, sink faucet, or toilet.

One cause of backflow is backsiphonage. Under certain circumstances, there can be an unexpected loss of system pressure in the distribution system. For example, a water main break or firefighting operation can lower distribution system pressure and cause the normal flow of water to reverse. Another cause of backflow is backpressure. Backpressure occurs when higher water pressure overcomes normal system pressure. Backpressure can result from a booster pump, interconnected water well, or pressure washing equipment. Backpressure or backsiphonage can cause backflow and pollute or contaminate the customer’s water system and public water system.

There are many possible situations that can create backflow. The important point is that without a properly functioning backflow prevention device, water can unexpectedly reverse in flow, drawing with it any undesirable materials from the points of use into the drinking water system.

The Importance of Prevention

Water has many domestic, agricultural, commercial, and industrial uses. Anywhere water is used, it may be mixed with undesirable materials. For example, landscape irrigation water me be contaminated with fertilizer or animal wastes. Commercial and industrial process water may be mixed either intentionally or inadvertently with chemicals or foreign materials.

Backflow prevention devices located immediately after the meter are required on all new commercial, industrial, and landscaping water services. District personnel conduct routine surveys of all existing commercial, industrial and agricultural services to assure that connections and uses are properly protected from cross-connection and backflow. Additionally, residential properties are occasionally surveyed for compliance with backflow prevention requirements.

Backflow Prevention Devices

Anywhere there is a potential for contamination or pollution of the drinking water system, a backflow prevention device is required. Devices can be small and simple, such as an anti-siphon vacuum breaker (AVB) on a hose spigot (photo), or large and complex, like those used on fire sprinkler systems (photo).








Backflow prevention devices used to protect the distribution system must be installed immediately after the water meter. These devices are owned and maintained by the customer or property owner. Installation of a backflow prevention device immediately after the water meter is often required on agricultural, landscape, commercial or industrial water services. This device only protects the water distribution system. Most of these types of services have a reduced pressure principle (RPP) assembly (photo). This type of device is installed above ground and has the necessary test connections to determine if each part of the device is operating correctly. It is important to note that the test valves on a backflow prevention device are only to be used by authorized personnel for testing the device. Connections to the test valves defeat the purpose of the backflow prevention device, and could damage it.






There are other types of devices to protect the water distribution system or on-site potable system. The type of device to be installed to protect the potable water system is determined based on water use and backflow potential. Types of backflow prevention devices are listed below:

  • Air Gap
  • Reduced Pressure Principal (RPP) Assembly
  • Hose Bib or Irrigation System Atmospheric Vacuum Breaker (AVB)
  • Double Check (DC)
  • Dual Check
  • Pressure Vacuum Breaker (PVB)
  • Spill-Resistant Vacuum Breaker (SVB)

Backflow Prevention Program 

Health agencies, water purveyors, contractors, and customers each have an important role in preventing unprotected cross-connections and backflow.

Federal and State law requires water suppliers to protect their water systems from contamination and pollution. Under the California Code of Regulations (CCR), all water purveyors must have a Cross-Connection Control Program. To view these regulations, please visit the website listed below, choose California Code of Regulations, and search for cross-connection control program.

Regulations and requirements for cross-connection control and backflow prevention in CCR Title 17 are found here.

As part of EVMWD’s cross-connection program, District cross-connection control specialists routinely conduct surveys of new and existing facilities to determine which type of backflow prevention is necessary to protect the water system.

EVMWD must assure that the distribution system is protected from contamination and pollution from backflow. If backflow prevention is required at the water meter, these devices must be tested initially and annually to assure they are operating correctly. In our area, tests and maintenance of backflow prevention devices must be conducted by County of Riverside Department of Environmental Health certified testers. For customer convenience, EVMWD maintains a list of testers with contact information. This list is included in the notification when annual testing is due, and is also available under Backflow Documents at the end of this section.

Certified testers are responsible for performing accurate tests, and repairing or replacing devices that fail. Additionally, testers must report all repairs and test results to EVMWD. After the testing is complete, the tester should give a copy of the test report to the customer and send the original report to EVMWD Backflow Prevention and Cross-Connection Control.

Plumbers, landscapers and other contractors are required to follow the latest publication of the Uniform Plumbing Code (UPC) regarding backflow and cross-connection prevention. Customers should contact state licensed contractors for modifications to their plumbing.

EVMWD considers any water that passes through the water meter as “used.” This is because EVMWD has lost control of the quality. After this point, the responsibility for preventing contamination and pollution of the drinking water system rests with the property owner or customer.

Backflow Prevention Device Test and Certification 

Annually, thousands to millions of gallons of water can pass through a backflow prevention device. Devices can be subjected to summer heat and freezing winter cold. Water chemistry can affect the performance of a device. For example, water that is even slightly hard can form deposits on moving parts. Small debris, such as sand particles can foul check valves and prevent moving parts from operating correctly. Additionally, moving water does wear on components over time. For these reasons, backflow prevention devices must be tested and maintained to assure they will work properly.

The backflow prevention device test only takes a few minutes. The test assures that each part of the device is operating correctly. If the device fails the first test, the tester must investigate the reasons for the failure, and if necessary, repairs must be made. Often, cleaning will correct the problem. To maintain proper protection, devices that fail the initial test must be repaired and re-tested within 15 days.

Customers who have questions regarding the annual notices they receive can call our Water Protection Department at (951) 674-3146 x8401, or  e-mail


Potable Water: Potable (POE-tuh-bull) water is water that does not contain objectionable pollution, contamination, minerals, or infective agents and is considered satisfactory for drinking and other domestic purposes.

Pollution: An impairment of the quality of the water to a degree which does not create a hazard to the public health but which does adversely and unreasonable affect aesthetic qualities.

Contamination: An impairment of the quality of the water which creates an actual hazard to public health through poisoning or through the spread of disease by sewage, industrial fluids, waste, etc.

Distribution System: The water system begins with the source of water such as groundwater or surface water. Wells, pumps and treatment facilities are part of the water system which delivers water to the distribution system. The water distribution system consists of tanks and pipes which store and deliver treated water to customers.

Backsiphonage: The term “backsiphonage” shall mean a form of backflow due to a reduction in system pressure which causes a sub-atmospheric pressure to exist at a site in the water system.

Backpressure: The term “backpressure” means any elevation of pressure in the downstream piping system (by pump, elevation of piping, or steam and/or air pressure) above the supply pressure at the point of consideration which would cause, or tend to cause, a reversal of the normal direction of flow.

Backflow Documents

Backflow Specification W-21A

Backflow Specification W-21B

Backflow Specification W-21C

List of Certified Backflow Testers

Backflow Test Report

Fluoride Information

EVMWD’s drinking water is a blend of three water sources: imported, ground and surface water. Nearly 65% of the District’s water supply is imported from the Metropolitan Water District of Southern California (MWD).

Starting in late October the MWD, under mandate from the state, will begin fluoridating its water supplies to a level that health experts say will provide the optimal protection against tooth decay. After vigorous debate and study, MWD determined that fluoridation would provide Southern California residents with an additional level of public health protection. EVMWD connections, at Lake Mills and Lake Skinner, will be among the first group of plants to start fluoridation.

Fluoride is naturally found in all water at levels ranging from none detected to 0.5 mg/L (parts per million). With the addition of fluoride from our imported water sources this level will increase slightly, to around 0.7 to 0.8 mg/L. Since EVMWD’s water supply is a mixture of water sources, the amount of fluoride in the District’s drinking water will remain at low levels and will not exceed the Department of Health Services’ (DHS) maximum contaminant level of 2 mg/L.

Adding fluoride to drinking water is considered a cost effective way to improve the health of the community, and costs less than two dollars per acre foot. Fluoride can reverse newly formed cavities and strengthen the enamel on your teeth. In addition to brushing your teeth, fluoride has been proven to help prevent tooth decay in communities that add fluoride to drinking water as opposed to those who don’t. While many studies exist about fluoride and your health, the American Dental Association (ADA) concluded that “the overwhelming…evidence indicates that fluoridation of community water supplies is both safe and effective.”

For more information on fluoridation, visit Metropolitan Water District of Southern California

Fluoridation Fact Sheet

Fluoridation Frequently asked Questions

Urban Water Management Plan

As part of the 2020 Urban Water Management Plan, the California Department of Water Resources (DWR) proposed six water shortage stages to be included in WSCPs.  As such, several of the response actions prescribed in Ordinance 225 and 233 (based on the five water shortage stages from the District’s 2015 WSCP) are no longer applicable. Therefore, Draft Ordinance – Water Shortage Contingency Plan/Water Conservation Program below is being proposed to replace the outdated ordinance. While EVMWD adopted a WSCP via Resolution 21-06-03 on June 10, 2021, the Draft WSCP below has been revised to align with the updated Draft Ordinance, and six water shortage stages consistent with the updated DWR recommendations.

2023 Water Shortage Contingency Plan
Ordinance 278 – Water Shortage Contingency Plan/Water Conservation Program

For Reference:

The Elsinore Valley Municipal Water District (EVMWD) prepared and adopted its 2020 Urban Water Management Plan (UWMP) and Water Shortage Contingency Plan (WSCP) as required by the Urban Water Management Planning Act (UWMP Act). EVMWD also amended its 2015 UWMP as this is a requirement of the Delta Plan for agencies that receive water from the Sacramento–San Joaquin Delta (Delta) to demonstrate consistency with the Delta Plan policy to reduce reliance on the Delta through improved regional water self-reliance.

The 2020 UWMP, WSCP, and 2015 Addendum have been successfully submitted to DWR and are available for download below:

2020 UWMP
2021 WSCP
2015 UWMP Addendum

Elsinore Basin Boundary Revision

Background – Sustainable Groundwater Management Act (SGMA)

The Elsinore Valley Municipal Water District (EVMWD) relies on local groundwater basins for a significant source of its water supply. Recognizing the importance of groundwater to communities like those served by EVMWD, the state legislature enacted the Sustainable Groundwater Management Act of 2014 (SGMA). SGMA provides local water agencies with important new groundwater management tools not previously available for the purpose of achieving sustainable groundwater use.

In order to implement SGMA, the California Department of Water Resources (DWR) has prioritized all of the Designated Groundwater Basins in California as high, medium, low, or very low. In accordance with SGMA, DWR requires the formation of Groundwater Sustainability Agencies (GSAs) that cover the entire basin for all medium and high priority Groundwater Basins. A GSA can be a single agency, or a group of agencies coordinating the sustainable planning and management of the basin.

In 2005, EVMWD adopted a Groundwater Management Plan (GWMP) for portions of the DWR-designated Elsinore Groundwater Basin (Basin No. 8-4), on which EVMWD relies for water supply. DWR has designated the Elsinore Basin as high priority. EVMWD has been actively managing groundwater resources in most of the Elsinore Basin for decades. However, the mapped boundaries of the basin are not well-aligned with the alluvial materials in the Elsinore Valley. Moreover, the EVMWD service area and GWMP do not cover a hydraulically distinct northwestern portion of the Elsinore Basin (No. 8-4), referred to locally as the Bedford-Coldwater area. EVMWD, in coordination with the City of Corona (City) and the Temescal Valley Water District (TVWD), has long been responsible for managing groundwater in the Bedford-Coldwater area, primarily through legal agreements between the City and EVMWD for managed withdrawals from the Coldwater area.

Basin Boundary Modifications 

Successful groundwater management relies on accurate delineation of groundwater basins. DWR has defined and designated 515 groundwater basins and subbasins in California. However, DWR and SGMA recognize that some of the groundwater basin designations are imperfect and, in some cases, could better support sustainable management with revised boundaries. SGMA includes a process for modifying groundwater basin boundaries from the current official delineations in DWR Bulletin 118. This process allows local agencies to request Basin boundary modifications from DWR, and provides opportunities for public and agency input. In November 2015, DWR finalized regulations for requesting modifications for basin boundaries and initiated a 90-day basin boundary modification period on January 1, 2016.

Proposed Boundary Modifications 

EVMWD has long managed the groundwater resources of the Elsinore Valley, including most of the DWR-designated Elsinore Basin. The DWR description of the Elsinore Basin identifies its extent as corresponding to the alluvial material mapped by the United States Geological Survey (USGS). However, the area of the Elsinore Basin mapped by DWR is not well-aligned with the alluvium currently represented in USGS maps. EVMWD is coordinating closely with the City of Corona and TVWD (formerly Lee Lake Water District) to explore a potential basin boundary modification request from DWR to realign the existing Elsinore Basin boundaries to match the alluvium of the Elsinore Valley and Temescal Wash areas, as mapped by the United USGS. This boundary modification request would also include creation of a new groundwater basin covering the northwestern portion of the Elsinore Basin from which Corona and EVMWD pump groundwater. This area is within the Temescal Wash watershed, and is locally referred to as the Bedford-Coldwater area.

Notification of the intent to explore a basin boundary modification request is being submitted to DWR in accordance with the requirements of SGMA. EVMWD, Corona, and TVWD plan to submit a single request for boundary modifications, as required DWR.

The basin boundary modification request will document the benefits and need for the Elsinore Basin boundary modifications and creation of the new Bedford-Coldwater Basin:

  • The Elsinore Basin and proposed new Bedford-Coldwater Basin boundaries would be modified to align with the alluvial deposits as mapped by the USGS, a change that would result in better correlation between the description in DWR Bulletin 118 and the mapped extent of the basins.
  • Groundwater within Elsinore Basin and the proposed Bedford-Coldwater Basin is hydraulically connected primarily beneath a narrow channel (referred to as Temescal Canyon) of Temescal Wash, and to a limited extent through shallow upland alluvial material. This limited connection provides a natural break for a basin boundary.
  • The proposed new boundary between the Elsinore Basin and the Bedford-Coldwater Basin  is located across this channel, generally separating two regional groundwater flow regimes.
    • Although some groundwater flow occurs across this boundary towards the Bedford-Coldwater area, most of the groundwater in the Elsinore Basin flows towards the basin center.
    • Groundwater flow north of this boundary is primarily towards the northwest and the center of the proposed Bedford-Coldwater Basin.
    • The canyon contains shallow bedrock and thin alluvial sediments, which restrict the volume of subsurface inflow across the boundary.
    • Recharge within both the Elsinore Basin and the Bedford-Coldwater area occurs primarily from runoff in adjacent hills east and west of the area rather than from flow between these distinct groundwater areas.
  • The Elsinore Basin south of the Bedford-Coldwater area is within the service area of the EVMWD, but the Bedford-Coldwater area is outside of EVMWD.
  • The TVWD and City service areas cover almost all of the Bedford-Coldwater area; those portions outside of these service areas are not within the service area of any local water agency. EVMWD, the City, and TVWD will coordinate with Riverside County for these currently unmanaged areas as required under SGMA.
  •  EVMWD, in coordination with the City and TVWD, has long been responsible for managing groundwater conditions in the Bedford-Coldwater area in accordance with legal agreements with the City of Corona for managed withdrawals from the Coldwater area.
  • Creation of this new basin would allow the area to be managed separately from the remainder of the current Elsinore Basin. This arrangement would facilitate activities for sustainable management of the groundwater within the Bedford-Coldwater area.

The modified basin boundary will be more consistent with both the hydrogeologic structure and historical and ongoing management of this shared groundwater resource. A map that shows the current and proposed basin boundaries can be accessed here Elsinore Basin Boundary map.

Public Notification and Consultation 

EVMWD is coordinating with the City of Corona and TVWD to prepare a combined boundary modification request package, as required. The Elsinore Valley Municipal Water District has notified and is coordinating with all other affected public water systems regarding this basin boundary modification request. EVMWD is also submitting to DWR a notification of intent to pursue basin boundary modifications in the Elsinore Basin.

EVMWD will consider adopting a resolution to submit the package to DWR at a Board meeting. Within five working days of DWR acceptance of the request, EVMWD will provide a notification of the submittal to local agencies and public water systems within the affected basin and any person or entity that has made a written request. This notice will include information regarding the procedural requirements and deadlines for public input regarding the basin boundary modification request.

For additional information or to request notifications on the proposed Basin Boundary Modification, please email or submit in writing to the following address:

Elsinore Valley Municipal Water District
Attn: Mr. Parag Kalaria
31315 Chaney Street
Lake Elsinore, CA 92530

Sustainable Groundwater Management Plan

The Elsinore Valley Municipal Water District (EVMWD) relies on local groundwater basins for a significant source of its water supply. Recognizing the importance of groundwater to communities like those served by EVMWD, the state legislature enacted the Sustainable Groundwater Management Act of 2014 (SGMA). SGMA provides local water agencies with important new groundwater management tools not previously available for the purpose of achieving sustainable groundwater use.

In order to implement SGMA, the California Department of Water Resources (DWR) has prioritized all of the Designated Groundwater Basins in California as high, medium, low, or very low. In accordance with SGMA, DWR requires the formation of Groundwater Sustainability Agencies (GSAs) that cover the entire basin for all medium and high priority Groundwater Basins. A GSA can be a single agency, or a group of agencies coordinating the sustainable planning and management of the basin.

SGMA enables eligible local agencies to form Groundwater Sustainability Agencies (GSAs), develop Groundwater Sustainability Plans (GSPs) for designated basins in their jurisdiction, and achieve groundwater sustainability within 20 years of GSP implementation. A GSA is responsible for developing and implementing a GSP to meet the sustainability goal of the basin to ensure that it is operating within its sustainable yield, without causing undesirable results.

EVMWD has formed a GSA and has begun the process of developing and implementing a GSP for the Elsinore Valley Subbasin. In order to prepare a prepare a comprehensive GSP, the EVGSA must consider the interests of all beneficial uses and users of groundwater. The EVGSA wishes to learn about your interests in the Elsinore Valley Subbasin and will conduct a series of public workshops for this purpose. EVMWD, in partnership with City of Corona and Temescal Valley Water District, formed the Bedford-Coldwater Groundwater Sustainability Authority, which is also preparing a GSP.

SGMA requires a communications plan to reach and involve the community and stakeholders around the Groundwater Sustainability Plan. The District recognizes that this is a critical aspect of ensuring that this process is transparent, engaging, effective, and fully available to the members of the community. Interested community members are encouraged to sign up to receive email updates including notices of upcoming community workshops. The workshop schedule will also be posted on this website.


The first GSP Stakeholder Meeting was held on November 5, 2019 at 4:00 p.m.

EVGSP Stakeholder Meeting #1 Appendix

The second GSP Stakeholder Meeting was held on Tuesday, September 15, 2020 at 4:00 p.m. virtually via Zoom.

EVGSP Stakeholder Meeting #2 Summary and Appendices

EVGSP Stakeholder Meeting #2 Attendees List

The third GSP Stakeholder Meeting was held on July 21, 2021 at 4:00 p.m. virtually via Zoom.

GSP Development 

All interested parties provided comments on the Elsinore Valley Subbasin GSP during the scheduled 90-day public comment period from July 7, 2021 – October 11, 2021.

The Public Hearing to adopt the Groundwater Sustainability Plan was held on December 16, 2021. You may view the notice here.

Final GSP and Annual GSP submitted to California Department of Water Resources can be found here:

GSP Appendices
Elsinore Valley Subbasin 2023 Annual Report
Elsinore Valley Subbasin 2022 Annual Report
Elsinore Valley Subbasin 2021 Annual Report

GSP Coordinator:
Jesus Gastelum
P.O. Box 3000
31315 Chaney Street
Lake Elsinore, CA 92531



A recent news story suggested pregnant women should avoid exposure to trihalomethanes in tap water – is this a concern?  

There isn’t a simple answer until more research is available. Trihalomethanes (THMs) are formed as a by-product of disinfection when chlorine, used to control disease-causing contaminants in drinking water, reacts with naturally occurring organic matter in the source water. In one new study, pregnant women who drank five or more glasses of tap water at THM levels of 75 parts per billion or higher were found to have a higher risk of miscarriage. The California Department of Health Services conducted the study, and says their results need to be replicated before specific health recommendations can be made. Pregnant women who have questions should consult their physician.

EVMWD’s average for Total Trihalomethanes is below the state and federal MCL of 100 ppb, though sample ranges can vary above and below this limit. EVMWD has reduced THM levels through treatment plant improvements and is studying disinfection alternatives, such as ozone to further reduce THM levels.

Does the District test for cryptosporidium? 

Yes, EVMWD monitors its water supplies and treatment plant for evidence of Cryptosporidium, a microorganism that inhabits lakes and rivers and can resist disinfection. It may cause gastrointestinal illness in humans if steps are not taken to remove it during water treatment. Upgrades to EVMWD’s water filtration system will ensure that Crypto is not a threat to our drinking water. Fortunately, Crypto is uncommon in groundwater, which supplies about half our drinking water. Cryptosporidium has not been detected in EVMWD tap water samples.

How can I improve the taste of my water?

Chill a pitcher of tap water for at least two hours to improve taste. Keep a chilled supply in the refrigerator so it will always be ready when you’re thirty.

I have a fish aquarium, what can I do to ensure that my tap water does not contain chlorine or chloramines, which can be harmful to fish?

Chloramine and chlorine are two of the safest chemicals used to kill bacteria, sometimes detected in water supplies. This valuable water treatment method is safe for humans but can be toxic to fish. Your pet store can recommend proper water treatment to remove chloramine or chlorine from your tap water. People who use blood dialysis equipment must also filter chloramines from their water supply.

Is fluoride added to our drinking water?

No. Fluoride is naturally occurring in water and soil in varying amounts. Fluoridation of public drinking supplies has been widely shown to prevent tooth decay. New legislation requires water districts to add fluoridation if outside funding sources, other than water rates, are available.

Is our drinking water safe? 

Yes. EVMWD is doing its part to consistently meet all state and federal water quality standards. Each year a report on drinking water quality is sent to customers to keep them informed about drinking water issues.

The water at my house seems to have a lot of minerals that leave deposits on my appliances and leaves spots on my glassware. What can I do about this?

Imported water sources from the Colorado River contain minerals that contribute to the hardness of the water. If you are considering installing a treatment device to soften the water, please refer to California Health and Safety Code Section 116785 to identify what, if any, restrictions apply.

What do the standards mean?

Drinking water standards are based on consuming water every day over a lifetime, without any harmful effects. They also take into account exposure to substances found in the air and in the foods we eat. Our drinking water supply is regularly tested for minerals, inorganic and organic compounds, radioactivity, bacteria, and other substances. Laboratories use state-of-the-art equipment to detect very small amounts of substances in water using the standards as guidelines for safety.

Where does our drinking water come from? 

EVMWD’s water supply is a blend of local groundwater, surface water from Canyon Lake reservoir and imported water from the Colorado River Aqueduct and the State Water Project. On average, nearly half our water supply is imported.  Refer to the Water Sources section of the website for more information.

Who regulates drinking water quality?

The United States Environmental Protection Agency (USEPA) establishes and enforces national drinking water standards. In California, enforcement of drinking water standards falls under the Department of Health Services, Drinking Water Field Operating Branch. Both agencies set Maximum Contaminant Levels (MCLs) for various compounds in water to provide for safe drinking water supplies.

Why are there taste differences during the year? 

Since our water is blended from different sources, taste, odor and appearance may vary occasionally. The blend between imported and local water varies most in the summer, when demand for imported water is highest. The age and condition of home plumbing can also affect the taste of drinking water.

Why does my tap water occasionally smell like rotten eggs? 

A sewer, or “rotten egg” odor, from your tap water could be the result of several problems in your own home, and may not be directly related to the water supply. If you detect the odor in your kitchen faucet, it could be the result of a partially clogged drain or a dirty garbage disposal. The easiest way to verify this is to check another faucet in the house. If the water from the other faucet smells fine, then, more than likely, the bad odor is a result of a dirty garbage disposal. Another common cause for a “rotten egg” odor from house tap water can be associated with your hot water heater. A hot water heater can produce a rotten egg odor from the hot water faucets if it is not set at the proper temperature. To determine if the odor is from the hot water heater, go the a sink closest to the water heater and fill a glass with water from the hot water faucet and a second glass from the cold water faucet and smell them. If the offending odor is detected only from the glass of water taken from the hot water faucet, the problem is most likely originating from the water heater. Flushing the water heater yourself, or contacting a plumber to perform the flushing, and then resetting the water heater to the correct temperature will, in most cases, solve the problem. Sewer gas can also enter your house through a sink drain, floor drain, shower or bathtub drain, if these fixtures are used infrequently and the water in the U-trap connected beneath the drain has dried up. The odor problem can be taken care of by running the faucet for several minutes to flush out the drain and to allow the water in the U-trap to refill. This, in turn, provides a water barrier within the trap that will keep sewer odors from entering your home through the drain.

Why does my tap water sometimes appear cloudy?

In areas served by wells, pumping can trap tiny air bubbles that temporarily cause water to appear cloudy. Tap water will clear if left to stand until the air bubbles are gone. Cloudy water is safe to drink. For more information, visit the water quality section of the website.

Why is my tap water occasionally brown or discolored?

Discolored or brown water from your tap can be caused by changes or disturbances in the water distribution main lines. Excessive fire hydrant use, a break in a water main line, area maintenance work, or a fire hydrant hit by a car, are possible events that can cause this condition. If you are experiencing discolored water from your tap, allow water to settle down for a short time and then flush all faucets in your house for several minutes. If the water does not clear up after the initial flushing, repeat the flushing two to three times every half hour. The problem should clear within 2-4 hours; however, if it doesn’t, please contact an EVMWD representative for further assistance.

Will a home treatment device help?

The best reason to install a point-of-use (POU) system is to remove objectionable tastes and odors. Most devices don’t make water more healthful. If you already use a POU system, be sure to follow the manufacturer’s service schedule. A poorly maintained POU system may actually increase the risk of microbial contaminants in drinking water.

Advancements with Ted Danson Promo Video

EVMWD joins Advancements with Ted Danson to discuss the impacts of climate change on local water supply and the innovative processes EVMWD is implementing to improve water quality and help the local environment.
(Aired August 19, 2023)