Drought

Font Size: + -

Feedback Print

Drought in San Luis Obispo

The City of San Luis Obispo's long-standing history of water-supply investments and water conservation efforts have resulted in the City’s water supply being in a better position now than ever before to withstand extended periods of drought. The City of San Luis Obispo is currently in the Monitor stage of its Water Shortage Contingency Plan.

This webpage will help you understand what the City of San Luis Obispo has done and continues to do to prepare for drought. This webpage also provides resources for residents, businesses, and visitors who want to learn about the City’s water supplies and how they can help conserve our valuable resources.

STAGE	WATER SUPPLY STATUS¹
Monitor	5+ years of available water supply	< Current Water Supply Status!
Watch	< 5 years of available water supply (up to 10% water shortage)
Warning	< 4.5 years of available water supply (up to 20% water shortage)
Alert	< 4 years of available water supply (up to 30% water shortage)
Severe	< 3.5 years of available water supply (up to 40% water shortage)
Extreme	< 3 years of available water supply (up to 50% water shortage)
Critical	< 2.5 year of available water supply (>50% water shortage)

¹City of San Luis Obispo Water Shortage Contingency Plan

Water Supply Outlook

The City of San Luis Obispo has four primary water supply sources including Whale Rock Reservoir, Salinas Reservoir (Santa Margarita Lake), Nacimiento Reservoir, and recycled water (for irrigation). The Utilities Department manages its water supplies by following the City’s State-approved, governing documents: Urban Water Management Plan (UWMP), Water Shortage Contingency Plan (WSCP), as well as the Water and Wastewater Management Element of the General Plan.

Currently, the City’s waters supply portfolio is in stable condition, with over 5 years of available water projected to be available for community use, putting the City in the Monitor Phase of its WSCP.

In fact, the City of San Luis Obispo’s drinking water system is the least vulnerable to supply impacts in San Luis Obispo County, according to a report released by the San Luis Obispo County Flood and Water Conservation District. In response to previous drought conditions, and in anticipation of future drought conditions, the County developed the Regional Water Infrastructure Resiliency Plan, for mitigating vulnerabilities and enhancing reliability, resilience, and optimum utilization of existing and future regional water infrastructure. The report ranked the City of San Luis Obispo with the highest resiliency risk ranking of all water purveyors in the county.

Plans and Policies

The California Department of Water Resources requires urban water purveyors to develop Urban Water Management Plans (UWMP) for long-term water resource planning to ensure that adequate water supplies are available to meet existing and future water needs.

The City of San Luis Obispo's Urban Water Management Plan describes and evaluates current and projected water supply sources through the year 2040, encompassing and going beyond the City’s projected General Plan build out. The water needed to serve the population projected in the General Plan is known as the City’s “Primary Supply”. Water needs to meet the City’s Primary Supply are projected using computerized models. These models simulate anticipated growth and development, anticipated water use by residents and businesses, and projected reservoir levels, including impacts from climate change. Because there are limitations in the ability to predict water demand in the future, conservative estimates of total community water use are made, resulting in the modeled water demands being higher than what is likely to occur.

In addition to the water needed to meet current and future water demand, City policy also requires water be set aside to act as a buffer for unforeseen or unpredictable long-term impacts. This is known as the City’s “Reliability Reserve”. As a result of several generations focused on water supply planning and the community’s conservation efforts, the City’s water supply portfolio exceeds both its Primary Water Supply and Reliability Reserve. This excess water is referred to as the City’s “Secondary Supply”. The City's water supply and demand projections help to ensure that there is enough water to support future community growth with a buffer to account for climate change and other unforeseen impacts to water supply availability.

Existing and Future Development

City staff understand that there may be increased concerns about development and growth in the City during periods of dry weather. However, it is important to remember that the large development projects currently being constructed within the City are a part of the City’s General Plan, which projects growth through 2035, and that the City’s “Primary Water Supply” ensures there is enough water to sustainably provide the water needed to support this increased population, even during periods of extended drought. Development projects are only approved when the City is certain adequate water supplies are available to serve the project.

In addition to planning for future population growth, the City’s Water Projection Model projects future reservoir levels, the volume of water that can be safely withdrawn from reservoirs each year, and how climate change may impact water resource availability. These planning practices ensure the City’s water resources remain adequate as the City grows. More information on how the City calculates it’s “Primary Supply” can be found in the Planning & Policies section above.

Expanding Our Water Supply

The City of San Luis Obispo’s multi-source water portfolio reduces the risk of a potential water shortage due to drought, loss of delivery infrastructure, or poor source water quality. The City has invested in a diverse water supply including three surface water reservoirs, recycled water produced at the City’s Water Resource Recovery Facility (WRRF), and groundwater production wells. Today the City’s water supply portfolio includes over 10,000 acre-feet of available water each year. The City’s the total water use for all uses is currently about 5,000 acre-feet of water per year, approximately half of what can be sustainably utilized each year.

Surface Water

The majority of the City’s water comes from the three surface water reservoirs: Whale Rock Reservoir, Salinas Reservoir (Santa Margarita Lake), and Nacimiento Lake. Having three surface water supplies allows for greater overall water storage and resiliency if one reservoir is unable to supply water. Furthermore, because these reservoirs are located in different watersheds, the City is able to capture water from rainfall events in different geographic areas of the county. The City prioritizes using water from Nacimiento Reservoir because its large watershed allows it to fill substantially year to year, and its total storage volume is nearly six times that of Whale Rock and Salinas Reservoirs combined. Maximizing the use of Nacimiento allows also the City to preserve water in its other reservoirs for use during critical water shortage periods.

Recycled Water

In 2006 the City began the production of recycled water at its Water Resource Recovery Facility (WRRF). Today about 5% of the City’s total annual water use comes from drought-resilient recycled water. Offsetting the use of potable water by utilizing recycled water for irrigation at local parks, business parks, and in common areas of large developments reduces the demand on potable surface water supplies by approximately 250 acre-feet per year.

Groundwater

The City overlies the San Luis Valley Subarea of the San Luis Obispo Valley Groundwater Basin. Once a major component of the City’s water supply portfolio, groundwater has not been utilized in significant volumes since the 1990s. All public supply production of groundwater ceased in 2015, however the City intends to renew its use of groundwater pending completion of several groundwater-related studies that will help the City understand the volumes of water that can be sustainably extracted from the basin each year and what treatment technologies would be most efficient to ensure high quality water is delivered to the community. Initial estimates indicate that groundwater could increase the City’s water supply portfolio by approximately 20% once fully utilized. More information about the City’s groundwater basin can be found within the recently completed Groundwater Sustainability Plan.

Other Sources

The City understands the water security we experience today is a result of many years dedicated to water resource planning and water conservation. The City takes action by planning today to ensure there is adequate water supplies for generations to come. The City remains engaged in discussions related to regional water resiliency through participation on the Water Resources Advisory Committee (WRAC), the Integrated Regional Water Management Group (IRWM), and through working closely with the County of San Luis Obispo and other local water purveyors to maintain and expand local water supplies.

Beyond expansion of local groundwater supplies, and sustainable management of surface water supplies, the City is nearing completion of a major upgrade to the Water Resource Recovery Facility (WRRF). The upgrade will help position the City to potentially utilize recycled water for groundwater recharge in the future. This will allow the City to recharge nearly 1,800 acre-feet of recycled water into the groundwater basin for storage and subsequent use.

Conservation - A Way of Life in San Luis Obispo

Conserving water is the most effective, immediate action the community can take to extend its water supply portfolio. The City is grateful to our community for its continued commitment to being good stewards of our water supplies. It may be surprising to know that the community’s total potable water use today is actually substantially lower than it was in past decades despite significant population growth over the last 50 years. In fact, residential indoor water use for the City of San Luis Obispo during 2021 was well below the 2020 State-mandated amount. Indoor water use was approximately 30 gallons per person per day on average in 2021 while the State-mandated amount was 55 gallons per person per day.

Water conservation regulations are often set at the State level and required to be implemented by local jurisdictions. Emerging from drought in the early 1990s, the State began adopting water conservation and water use efficiency regulations, including efficiency standards for indoor fixtures such as toilets and faucets and outdoor fixtures such as sprinklers and drip irrigation systems. In 2010 and 2015 the State adopted and updated its Model Water Efficient Landscape Ordinance (MWELO) to limit the amount of water that can be used on new landscapes and ensure that water used for irrigation is used efficiently. In many cases the City has adopted local ordinances to address wasteful water use beyond what has been required by the State.

What the City is doing?

The City is continuously looking for ways to conserve water, reduce water loss from distribution system leaks, secure new water supplies, and build greater resiliency into our treatment plant and distribution system. For example, did you know that recycled water is primarily used to irrigate parks, medians, and other community areas around the City? The use of recycled water at these locations allows the City to preserve approximately 250 acre-feet (over 81 million gallons) of valuable drinking water in the City’s reservoirs each year. The Utilities Department also provides complementary water-efficient items free of charge to water customers, including low-flow showerheads, faucet aerators, hose nozzles, and leak detection tablets. In 2021 the City also invested in a software platform that will help to pinpoint public outreach efforts to inefficient water users within the community.

In addition to these items, the City works to manage and implement effective programs to ensure compliance with the most current State regulations. Once a year, the City conducts a Water Loss Audit to help identify and reduce the water lost due to leaks within its distribution system. Water loss audits help the City prioritize the replacement of aging infrastructure to reduce the risk of water main breaks, and to also identify internal City operations that could be modified to reduce water use. Similarly, the City recently began upgrading its aging mechanical water meters to digital meters that have the ability to register small water leaks that occur within the community.

In the event a water shortage is declared by the State, or by the City Council if local supply conditions meet criteria set forth in the City’s Water Shortage Contingency Plan (WSCP), the City will implement several long and short term water conserving measures. The City’s water shortage response is dependent on the ability to temporarily augment water supplies and to reduce water demand. This means combining a variety of strategies including community outreach, indoor water efficiency regulations, and outdoor irrigation restrictions, each increasing in intensity as the City’s water supplies are further restricted. During periods of extreme drought. restrictions may be necessary to conserve the City’s water supply for vital services including domestic uses, sanitation, and fire protection. Details of the actions the City would take at each stage are outlined in the City’s WSCP.

What can you do to help?

Water conservation saves customers money through reducing costs associated with water treatment, water distribution, and the deferral of expensive source water acquisition projects. Conservation also lowers greenhouse gas emissions by reducing the amount of water that the City has to treat and distribute, the amount of wastewater that is required to be collected and treated, and by reducing gas and electricity use required to heat this water within homes and businesses. The City of San Luis Obispo has long benefited from serving a community that cares about water. In fact, the investments that the community made in reducing its total water use from approximately 8,000 acre-feet per year in the late 1980s to approximately 5,000 acre-feet per year today is a large reason why the City has remained secure through the current drought. This 3,000 acre-foot per year reduction in water use occurred during the same period that the City's population grew by approximately 10,000 people, truly underscoring how powerful ongoing conservation is in ensuring a water-secure future.

Check out our Conservation Tips and Tricks page for ways you can save water at your home or business.
Remember, California needs trees, and trees need water! Learn how to maintain your trees during drought with the California Urban Forests Council.
Be a leak detective! Discover ways you can catch costly water leaks on our Check for Leaks page.
Report leaks and instances of water waste through our online Water Waste Violation form.

Moving into the Future

The City understands that concerns about drought are growing across California and are likely to continue being common place as California experiences the highest variability in rainfall of any state in the United States. We remain focused on securing new water supplies, building greater resiliency into our treatment plant and distribution system, and reducing water use within the community.

Although we are currently water secure, we know that this security is in large due to continued investments in water supply projects over many generations. In order to continue to expand the City's water supply portfolio, ensuring security for future generations, staff are working on several projects that will result in increased water supply availability. Most notably, the City is currently finalizing its grant-funded groundwater contaminants delineation study, which is the first step in ensuring that local groundwater supplies are safe to drink and readily available to our community. Additionally, the City is in the middle of upgrading its Water Resource Recovery Facility in order to position the City to utilize highly treated recycled water for groundwater augmentation or surface water augmentation in the future. These two projects are the first steps in maximizing the use of local groundwater and recycled water supplies.

City of San Luis Obispo Water Conservation Rules

Water cannot be wasted due to substandard, leaky, or faulty water fixtures.
Water cannot flow off a property to constitute water waste runoff.
Restaurants must continue only serving water upon request.
Drinking water cannot be used to wash down sidewalks, driveways, or parking areas except to alleviate immediate fire or sanitation hazards.
Drinking water cannot be used for major construction activities, such as grading and dust control.
Outdoor watering within 48 hours after at least 1/4 inch of rainfall is prohibited.
The State of California is continuing to prohibit commercial, industrial, and institutional sites, including property irrigated by Homeowner Associations, will be prohibited from using drinking water to irrigate “non-functional turf”.
- Non-functional turf is defined as turf, or grass, that is solely decorative and not regularly used for recreation or civic and community events.
- Watering that ensures the health of trees and other perennial non-turn plantings (plants that live more than two years) or to address immediate health and safety needs is exempt from the turf irrigation regulations.
- Sites irrigated with recycled water are exempt from this restriction.

Archived News

City of San Luis Obispo, CA

FIND A SERVICE

I WANT TO...

Stay Connected

Drought

Drought in San Luis Obispo

Surface Water

Recycled Water

Groundwater

Other Sources

City of San Luis Obispo Water Conservation Rules

June 2 Council Meeting Recap

Mayor to Deliver 2026 State of the City Address Next Week

SLO in Motion Update – May 30, 2026

SLO in Motion Update – May 23, 2026

This Week, SLO Celebrates the People Behind Public Works & Utilities

SLO in Motion Update – May 16, 2026

Save the Date: State of the City on June 9

SLO in Motion Update – May 9, 2026

May 5 Council Meeting Recap

SLO in Motion Update – May 2, 2026

SLO in Motion Update – Apr. 25, 2026

Apr 21 Council Meeting Recap

What are People Asking SLO About? Here are the Top 10 Requests

SLO in Motion Update – Apr. 18, 2026

Volunteers Celebrated at Appreciation Lunch

SLO Installs ‘Clean CA Community’ Sign at Highway 1

Apr 7 Council Meeting Recap

City of San Luis Obispo Joins 2026 Wyland National Mayor’s Challenge for Water Conservation

SLO in Motion Update – Mar. 21, 2026

Public Information Session: Understanding Utility Rates