At the June meeting of the Delta Stewardship Council, Delta Watermaster Jay Ziegler updated the Council on the implementation of the Delta Alternative Compliance Plan for compliance with SB 88 and the Delta Dry Year Response Plan.
Delta Alternative Compliance Plan
In 2015 the legislature passed SB 88, requiring water diversions to be measured and reported statewide. At the time, water users in the Delta had a poor reporting rate. However, due to the efforts of previous Delta Watermaster Michael George, along with others, the Delta now has the highest rate of compliance in the state. This, despite the difficulty of measuring diversions in the Delta due to cost and feasibility issues.
SB 88 had three pathways to comply:
- Direct metering of diversions
- Develop an individual alternative compliance plan, which would be based on metrics provided by a single or integrated set of users, such as in the case of Suisun Marsh, where they worked together to develop metrics that accurately reflected their actual diversion and water use practices.
- Build an integrated platform that is an open-sourced alternative compliance program that uses technology to determine water use. The result is the Open ET platform.
The Open ET effort involved various stakeholders from across the spectrum, including NASA, JPL, engineering firms that work in the Delta, the Delta water agencies, and academic institutions.
“What this technology platform has delivered for the first time in California is alignment with water rights, a place of use, and reporting of the actual applied water in that place of use,” said Mr. Ziegler. “Think of the Delta as approximately 2300 points of diversion with applied water use, riparian rights, and a polygon map that aligns a place of use with the actual applied water … It’s 2300 puzzle pieces fitting together where the water is applied on the ground. And we can validate the exercise of legal water rights aligned with the place of use in a way that’s never been done before in the state.”
“Those participating in this program in the Delta are frankly best in class in providing a model and how to use open ET technology to provide the best highest quality water use, and then overall consumptive use information in the Delta of anywhere in California.”
Currently, about half of the Delta is using the Open ET platform, which Mr. Ziegler attributed to the leadership and support of the South and Central Delta water agencies.
“Next year, I want this entire graph to be all in light blue, meaning that all reporters in the Delta are on the platform,” he said. “About half the filers are on the platform, and there are polygon place of use files for another 20% of diverters, which are still working on finalizing their shape files and reporting into the website. So we’re hopeful that in year one, we might get close to 70% reporting on the Delta ACP platform, which would really be extraordinary. … And that’s significant because then we can have an apples-to-apples conversation about consumptive use of water in the Delta if all reporters are actually reporting on the same platform.”
Refinement of the platform is ongoing. The Delta Measurement Experimentation Consortium includes Delta diverters, the Delta water agencies, and statewide water agency interests, who continue doing experiments to further refine the Open ET platform, such as experiments on tail water measurements and the effects of different elevations and geographies in the Delta.
“The beauty of open ET is that we can actually get under the hood and look at the assumptions that built the software,” said Mr. Ziegler. “So we can work with individual farmers. And we’re hearing from farmers that they’re actually using this as a tool to think about practices that may enhance their crop productivity or crop substitution. So it has really provided some additional benefit to Delta users in this process.”
Delta Drought Response Pilot Program
The Delta Drought Response Pilot Program was launched in January 2022 in response to consecutive dry years, low reservoir storage, and drought-constrained water deliveries to project contractors. The program was developed in partnership with the Department of Water Resources, the Office of the Delta Watermaster, and The Nature Conservancy, and in coordination with Delta water users. The collaborative program helps improve mutual understanding of agricultural practices and water conservation opportunities in different regions within the Delta.
Under the program, farmers receive financial incentives to reduce their water use and protect wildlife and water quality in the Delta. The fields were monitored using Open ET, Eddy covariance instruments, and satellite data to verify the amount of water conserved.
DWR allocated $8 million for grants for the program’s first round, in which more than 8,700 acres were enrolled. A report published in March 2023 describes the initiation, solicitation, selection, and analysis of incentivized water conservation actions taken by Delta agricultural water users during the program’s first round. Thirty-three projects were identified that used practices that could be used to reduce water use in the Delta, such as deficit irrigation, crop substitution, and fallowing. The hypothesis was that those projects could save 20,000 acre-feet of water; however, actual results yielded less than 25% of those projected water savings.
With funding allocated in the Budget Act of 2022, the program launched a second phase with an additional $10.8 million in grant funding available for the water year 2023 (October 1 to September 30), with 16,116 acres enrolled in water-saving practices and 6,400 acres enrolled in bird benefit practices.
“This project now continues into one of the wettest years on record in California,” said Mr. Ziegler. “So in that, I think we’ll learn a bit more about the hydrodynamics of the Delta in working across this lens of this extraordinary dry year to an extraordinary wet year. … Additionally, we also have six field stations doing telemetry and ET modeling to also validate our water savings outcomes. That’s another interesting application of Open ET – to better understand water budget dynamics in the Delta.”
Looking forward
In this year of whiplash hydrology, Mr. Ziegler said the question on all our minds is, how does that inform more sustainable investments across the Delta? So there is an informal dialogue occurring across the Delta Conservancy, the Department of Water Resources, the Stewardship Council, the State Water Board, the Office of the Delta Watermaster, and others to brainstorm projects with local support that can be put forward as viable, sustainable projects in the context of a potential climate resilience bond for the 2024 ballot.
“We’re trying to work ahead of the curve, if you will, in identifying important projects throughout the Delta that can contribute to water quality, flood safety, habitat enhancement, recreational benefits, as well as overall sustainability in the context of the Delta Plan,” said Mr. Ziegler. “We’ve had record flows down the San Joaquin for months now that are really stressing the system. What will we learn from that? How much sedimentation will we see at the head of Old and Middle Rivers? Do we need a more strategic program for dredging to protect both water quality and hydrology in the south Delta?”
“The future is more science collaboration,” he said. “I look forward to working with you all at the Stewardship Council and the Delta Science Program as we strive to promote a more sustainable Delta and work to achieve results,” he said.
