Dierdre Des Jardins, CALIFORNIA WATER RESEARCH
On Wednesday, August 28, 2019, the Sacramento Press Club hosted a panel discussion, “Droughts, tunnels & clean water.” The panel included Wade Crowfoot, Secretary of Natural Resources, Jeffrey Kightlinger, general manager and CEO of Metropolitan Water District, and Jennifer Pierre, general manager of the State Water Contractors. Stuart Leavenworth from the LA Times moderated the panel.
The Newsom administration has committed to modernizing Delta Conveyance to protect water supplies from earthquakes and sea level rise. In a July 8 update to the Metropolitan Water District’s Water Planning and Stewardship Committee, Crowfoot stated, “if you are a state agency and you are building infrastructure that you want to exist and be operating in 2100, you need to plan for between 5 and 10 feet of sea level rise.” Crowfoot emphasized that sea level rise was one of the reasons the Newsom administration supported the Delta tunnel, stating, “when we’re talking about really protecting our water supply against sea level rise and saltwater intrusion, the underground conveyance or the tunnel becomes quite important.”
The Newsom administration has relied on assertions by the Department of Water Resources that the North Delta is 15 feet above sea level. But as explained in California Water Research’s August 12 blog post, this assertion is misleading. In the North Delta, only the top of the Sacramento River levee is 15 feet above sea level. Elevations at Courtland and Hood range from -1 to 8 feet above sea level, and the bottom of the Sacramento River is over 20 feet below sea level. California Water Research has recommended that new modeling be done of the performance of the North Delta intakes with high sea level rise.
During the Q&A period at the Sacramento Press Club luncheon,Deirdre Des Jardins advised the attendees of these facts. She asked Kightlinger and Pierre if they would commit to modeling the performance of the North Delta intakes with 10 feet of sea level rise and widespread levee failure. In response, Kightlinger stated that MWD is looking at moving the Delta tunnel intakes 20-30 miles north to accommodate sea level rise. Kightlinger stated that MWD is evaluating the increased costs of a longer tunnel, versus the benefits of extending the lifetime of the project.
It is unclear what intake locations Kightlinger was referring to. But in 2010, the Department of Water Resources evaluated two sets of locations north of Freeport, which would resist salinity intrusion with 10+ feet of sea level rise. The first set includes two locations on the west bank of the Sacramento River in South Sacramento, the second set, two locations upstream of the American River confluence. A third set of alternative locations was downstream of the confluence with Steamboat Slough. (see below.) These would benefit salmon but have less resistance to salinity intrusion.
These alternative locations were considered and rejected in 2010, partly on the basis of modeling by Resource Management Associates (RMA) which was interpreted to show no impacts from salinity intrusion at any of the proposed intake locations. But as explained in California Water Research’s August 6 blog, the 2010 RMA modeling is obsolete and has major limitations. The 2010 RMA modeling assumed 55 inches of sea level rise, and no failure of North Delta levees. The California Ocean Protection Council’s current estimate of maximal sea level rise by 2100 is 10 feet or 120 inches. This is over twice the 2010 estimate.
As part of “assessment of efforts to modernize Delta Conveyance,” California Water Research has recommended that the Newsom administration document that the WaterFix intake locations need to be reassessed for performance with 10 feet of sea level rise and widespread levee failure.
Source: https://cah2oresearch.com/2019/09/02/delta-tunnel-mwd-weighs-moving-intakes-20-30-miles-north-for-sea-level-rise/
