The Dutch Slough Tidal Marsh Restoration Project site, located in the Sacramento-San Joaquin Delta near Oakley, California. Jonathan Wong / DWR

MEETING: Delta Council told current pace of habitat restoration in the Delta unlikely to meet state’s ambitious goals for decades

Habitat restoration projects in the Delta have become increasingly important as our understanding of their role in supporting native aquatic and providing flood protection deepens.  As such, several state agencies and initiatives have set goals for restoration in the Delta, such as the Central Valley Flood Protection Plan, the 30×30 initiative, and the voluntary agreements. 

In particular, the Delta Stewardship Council’s Delta Plan sets a goal of 60,000 – 80,000 acres of diverse habitats in the Delta, which, if completed, would be over 100 square miles.   However, if the current pace of restoration continues, it will be decades before this goal can be achieved, Steve Rothert, Chief of the Division of Multi-Benefit Initiatives for the Department of Water Resources (DWR), told the Delta Stewardship Council at their January meeting.

The Department of Water Resources has made substantial progress restoring habitat in the Delta over the last decade.  Currently, the Department has 36,600 acres of restoration underway; 28,000 acres are either completed or under construction, and another 8,500 acres are in the planning stages and will be completed by 2030.   These projects are done for several reasons: Some are for mitigation, others are for enhancement, and some are funded through grants. 

However, these are complex projects with many moving parts, which accounts for some of the lengthy timeframes.  “These projects can represent decades of planning,” said Charlotte Biggs, DWR Program Manager.  “Sometimes, we talk about projects in terms of groundbreakings, but there’s so much work in the planning process to get to those points.”

The risk of high water events is a constant challenge.  DWR tends to prioritize the sites that haven’t had recent investments in levees, as those are usually good sites for restoration.  However, the Grizzly Slough project and the Prospect Island project were flooded during the recent storms. 

The problem is, the longer it takes to restore them, the more risk we have,” said Ms. Biggs.  “These sites can be very vulnerable.  Now we’re facing more costs to reclaim the sites after high water events.  So we have to take that into consideration, especially when we’re using grants or special funding.”

Making the connection

As projects are completed, they are starting to connect together to provide corridors of restored habitats.  One example is the Big Notch project at the Fremont Weir, which broke ground in June 2022. 

In the heart of our flood control system, we’re modifying a hundred-year-old flood control system to be friendlier for fish and to create seasonal floodplain habitat that’s desperately needed,” said Ms. Biggs.  “The project will help achieve the inundation target for the Yolo Bypass.

Importantly, the Big Notch project connects to the Cache Slough, where tidal wetlands are being restored.  “Because as we create more connectivity through the bypass, we are eliminating those fish passage barriers, so that restoration in Cache Slough will create the habitat, the food source, and the shelter to help the fish survive through those areas.

Similarly, the Lookout Slough project started in May of 2022 and connects to two smaller completed projects.  “So while some of these projects can seem kind of small, in the big picture, when we start to connect them, they become more significant, and the benefits will be more significant,” said Ms. Biggs.

Decades to meet the state’s ambitious restoration goals

The Department of Water Resources has several projects currently under construction, with the Prospect Island project nearing the construction phase.  Nonetheless, Mr. Rothert, pointed out that the pace and the scale of restoration needs to increase to achieve the state’s restoration goals. 

If we roughly average the pace of restoration that we’ve been managing over the last couple of decades, it’s about 1,500 acres a year,” he said.  “So achieving the 60 to 80,000 acre restoration goal at that pace would take 40 to 50 years.”

Mr. Rothert closed by saying, “Given the overlay and the alignment of DWRs restoration projects with the priority areas of the Delta Stewardship Council, our agencies are very much working together to achieve the restoration goals and that the success of our projects translates into success for the Delta Stewardship Council in making progress towards the overall vision.”

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