The Imperial Irrigation District (IID) has signed implementation agreements formalizing its commitment to join both the existing Western Energy Imbalance Market (WEIM) and the planned Extended Day-Ahead Market (EDAM) that will launch next spring.
In announcing its decision on the IID website, the utility cited reduced costs for customers, enhanced system reliability, and the ability to modernize its systems as key reasons for its decision.
"As a large public power provider in California, IID is pleased to join both the Western Energy Imbalance Market and the Extended Day-Ahead Market," said IID General Manager Jamie Asbury. "This is a significant step toward modernizing how we purchase and manage power, which will translate into savings for our ratepayers annually by giving us the ability to react much faster to energy market conditions. This also aligns IID more closely with emerging regional energy practices, yet allows us to retain our independence as an energy Balancing Authority."
With implementation agreements now signed, IID becomes the first utility to concurrently pursue joining both ISO-operated markets. When IID's participation begins in 2028 as targeted, it will mark the first time all California balancing authorities are participating in ISO-operated electricity markets.
IID is the largest irrigation district in the nation and a key player in managing the Colorado River water supply chain. The 114-year-old utility supplies electricity to 166,000 customers in the Imperial Valley and surrounding areas of Southern California.
Elliot Mainzer, president and CEO of the ISO, said he was "honored to welcome the IID to the WEIM and EDAM family.
"It is exciting to know that for the first time all of the California balancing authorities will be participating in the ISO markets. Together with our regional partners outside of California, this will provide even greater reliability and financial benefits across the EDAM footprint."
In addition to the Turlock Irrigation District, which also has recently committed to join EDAM, four other energy providers have signed EDAM implementation agreements committing their market participation. PacifiCorp and Portland General Electric will join the market in 2026. The Los Angeles Department of Water and Power and the Balancing Authority of Northern California, which includes the Sacramento Municipal Utility District, have signed agreements to join in 2027.
The ISO and its stakeholders have designed the day-ahead market to build on the proven track record of the WEIM. Just under $7 billion in cost-saving efficiencies have been delivered to the WEIM's 22 participants across 11 Western states since the market began managing real-time, least-cost energy transactions in 2014.
The real-time market has also helped to avoid more than one million metric tons of greenhouse gas emissions and continues to grow, with two additional participants expected to begin participating in 2026.
The EDAM has been set up to unlock those benefits for WEIM participants in the day-ahead timeframe, where the bulk of energy transactions occur, and the reliability, economic and environmental benefits will be even greater.
The California Independent System Operator (ISO) is a nonprofit public benefit corporation dedicated, with its partners, to continuous improvement and secure operation of a reliable grid operated for the benefit of consumers. It provides comprehensive grid planning, open and nondiscriminatory access to one of the largest networks of high-voltage transmission power lines in the world, and operates a $9 billion competitive electricity market. Recognizing the importance of the global climate challenge, the ISO is at the forefront of integrating renewable power and advanced technologies that will help provide a sustainable energy future efficiently and cleanly.
The Western Energy Imbalance Market (WEIM) is a real-time wholesale energy trading market that enables participants anywhere in the West to buy and sell energy when needed. The Western Energy Markets Governing Body is the governing authority designed by regional stakeholders and has shared authority with the ISO Board of Governors to resolve rules specific to participation in the WEIM.