Restoring Delta Tule Marshes Is More Complicated than Typically Assumed - John Zentner
The Take Home: a Summary
Restoring the Delta’s tule marshes can alleviate rising sea levels, create endangered species habitat, and reduce global warming, but making restoration projects work in the Delta will be more difficult than simply breeching the adjacent levees. Much of the Delta has subsided well below mean sea levels. Breeching local levees will result in large expanses of shallow water that are not likely to soon transform into marshes.
Faced with just this situation in the east Delta, we tried transplanting large plugs of tule marsh, seeding and a variety of other methods on a flooded Delta site over several years. A unique nursery product coupled with careful water level management finally worked. The take-home lessons:
- Good hydrologic analyses with local tidal gauging are essential.
- Seeding is not an efficient strategy for tule marsh restoration.
- Similarly, distributing a few large clumps of excavated tule marsh won’t produce large expanses of tule marsh even over 4 to 5 years.
- Nursery-grown “superplugs” may be the most effective strategy in tule marsh restoration.
- Whatever method is chosen, maintaining control over water levels until an appropriate equilibrium is reached is critical.
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