SD Water Authority Mulls New Aqueduct

Addressing the San Diego region’s limited local water supplies with innovative ideas is something the San Diego County Water Authority has become known for. Using expertise gained from decades of successful planning and projects, the Water Authority is developing strategies to reduce the future cost of water that sustains the economy and quality of life across the county.

A $5 Billion Water Project Could Drill Through Anza-Borrego Park. Is It a Pipe Dream?

It would be arguably the most ambitious public works project in San Diego history.

The envisioned pipeline would carry Colorado River water more than 130 miles from the Imperial Valley — through the Anza-Borrego Desert State Park, tunneling under the Cuyamaca Mountains, and passing through the Cleveland National Forest — to eventually connect with a water-treatment plant in San Marcos. An alternative route would run through the desert to the south, boring under Mount Laguna before emptying into the San Vicente Reservoir in Lakeside.

Regional Conveyance System Study-Phase B-November 2020

Board Approves Next Phase of Regional Water Conveyance System Study

The San Diego County Water Authority’s Board of Directors today authorized staff to launch the next phase of a study assessing options for long-term water deliveries to sustain the region’s economy and quality of life.

The decision follows months of community dialogue about Phase A of the Regional Conveyance System Study, which was released in August. The study demonstrated the technical viability and economic competitiveness of two routes for an aqueduct to transport the Water Authority’s independent, high-priority Colorado River water to San Diego County.

Over the next 15 to 18 months, Water Authority staff will undertake Phase B, focusing on economic analysis of the two conveyance route alternatives and exploring partnerships that could provide significant benefits to an array of stakeholders and potentially reduce the cost of project development. At the end of Phase B, the 36-member Board will again decide whether to continue with regional conveyance project planning – and if so, how to proceed.

Long-term planning

“These issues are complex and the decisions never easy, but the Board chose today to keep all water supply and delivery options on the table in light of future uncertainties,” said Gary Croucher, chair of the Water Authority’s Board of Directors. “I look forward to learning from Phase B and working with the Board to decide on next steps when that study phase is done. We also look forward to working with MWD in coming months to explore long-term options for continued use of its Colorado River Aqueduct.”

The Water Authority is the long-term water planning agency for metropolitan San Diego County and the region’s wholesale water provider, serving 3.3 million people and a $245 billion economy in partnership with its 24 retail member agencies.

Half of the Water Authority’s supplies are from two landmark 2003 water conservation agreements – one that boosted water-use efficiency in collaboration with the Imperial Irrigation District and another to line sections of the All-American and Coachella canals with concrete to reduce seepage. Both agreements are part of the 2003 Quantification Settlement Agreement, the largest ag-to-urban water transfer in U.S. history.

Water supply reliability

Conserved water from the QSA is transferred to San Diego County through an Exchange Agreement with the Los Angeles-based Metropolitan Water District of Southern California. MWD owns the only facilities available to transport Colorado River water to San Diego County. The cost of using MWD facilities to deliver the Water Authority’s QSA water has increased 30% over the past five years alone.

The Water Authority’s Exchange Agreement with MWD ends in 2047, and the Water Authority is working to develop conveyance alternatives in order to manage future cost and risks.

“While 2047 may seem distant, major water infrastructure projects take decades to develop, plan and build,” said Croucher. “By advancing to Phase B of the conveyance study, the Water Authority is taking prudent steps to ensure long-term water supply reliability for the region.”

In order to address the cost and risk uncertainties associated with the use of MWD facilities, the Water Authority’s Board in June 2019 approved a study of the viability of a new regional conveyance system that would deliver water from the Colorado River to San Diego County and also might provide multiple benefits across the Southwest. Three potential pipeline routes were studied in Phase A, which concluded in August 2020 that two alternatives (3A and 5A) are cost-competitive with other options, such as continued use of MWD facilities.

Water Authority staff and consultants began in August an extensive series of briefings and outreach on Phase A results and consultant reports. The Board’s goal was to ensure a full exchange of information and viewpoints in a transparent process. Outreach across numerous platforms engaged member agencies, other local stakeholders, the Imperial Valley, and Borrego Springs.

Partnership opportunities

With today’s Board vote to approve Phase B, Water Authority staff will focus for the next several months on economics, partnerships, legal analysis, and stakeholder outreach. Phase B will help address questions about mitigating short-term rate impacts of a project, the benefits of  potential partnerships and funding opportunities, developing a plan of finance and the requirements of existing agreements, as well as explore with MWD options for long-term water deliveries to the San Diego region using MWD facilities.

 MWD issues to be addressed will include analysis of:

  • Historic and projected future increases in MWD’s water rates and charges
  • MWD’s current planning assumptions
  • Costs and water yield of MWD’s current and planned projects
  • Future demand for MWD water
  • Other MWD rate drivers

Phase B will apply the same rigorous analysis to Water Authority rate and cost projections. Water Authority staff will also begin the process of engaging more formally with stakeholders on potential partnership projects identified in Phase A, including public-private-partnerships, bi-national projects, renewable energy projects, regional operational storage projects, Salton Sea-related projects, and partnerships with tribes, federal and state governments, and member agencies.

For more details, go to

Water Authority to Host Public Session on Economics of Regional Conveyance Study

The San Diego County Water Authority will host an online public information session on Oct. 27 about economic considerations related to the proposed Regional Conveyance System. The virtual event will run from 10 a.m. to noon.



Regional Conveyance Study-RCS-Water Supply

Water Authority to Host Public Session on Economics of Regional Conveyance Study

The San Diego County Water Authority will host an online public information session on Oct. 27 about economic considerations related to the proposed Regional Conveyance System. The virtual event will run from 10 a.m. to noon. To reserve a spot, email .

Meeting participants can:

  • Learn about alternatives the Water Authority Board of Directors is studying to secure San Diego County’s future water supplies
  • Ask the experts about key issues
  • Understand the feasibility and costs of building a conveyance system to deliver San Diego County’s Colorado River supplies
  • Discuss potential next steps

In June of 2019, the Water Authority’s Board of Directors approved a study of the viability of a new regional conveyance system that would deliver water from the Colorado River to San Diego County and could provide multiple benefits across the Southwest.

Regional Conveyance Study

The Phase A report, released in August 2020, found that building a new conveyance system to transport the region’s supplies from the Quantification Settlement Agreement is cost-competitive with other long-term strategies for meeting the region’s water needs.

At its August 2020 meeting, the Water Authority’s Board decided to continue the regional discussion about the study until November 19, at which time the Board is expected to decide whether to move ahead with Phase B of the study.

To learn more about the Regional Conveyance System Study or to read the executive summary and the full report, go to

Potential pipeline routes

Regional Conveyance Study-RCS-Economics-Water Supply

A study of a new regional water conveyance system to deliver high-priority Colorado River supplies from the Imperial Valley shows three potential routes to move the water. Graphic: San Diego County Water Authority

Each of the potential conveyance routes would connect to the tail end of the All-American Canal where it meets the Westside Main Canal in the southwest corner of Imperial Valley.

Opinion: An Aqueduct to San Diego is Worth Studying

Fresh on the water scene in Imperial County is a proposal from the IID’s neighbor agency San Diego County Water Authority. The SDCWA is an umbrella organization that comprises 24 members including all the cities and water districts in San Diego County.