Earlier this month, FISHBIO wrote about the history of the California Delta on The Fish Report, its weekly newsletter. The article describes how the Delta has been transformed from a freshwater wetland 200 years ago to an agricultural zone today:
Building levees was a learning process, mostly due to the highly sought-after peat soil. While peat soil was rich for farming, it lacked any structure to serve as a solid barrier. Initial levee walls were four feet high and 12 feet wide at the base. They were built by hand, primarily by Chinese immigrant laborers. Unfortunately, when the peat dried, it would crack and even blow away, making it very difficult to maintain levee walls. By the late 1870s, steam-powered dredges replaced hand labor, and helped to move in stronger alluvial soils (such as clay, silt, or gravel) from the river channel. The process was more efficient, cost effective, and created a longer-lasting levee.
While the work of building levees and creating “pseudo-islands” has turned the Delta into a highly productive agricultural region, it has had some unintended consequences. Back when the Delta was transformed, the levee builders didn’t think to expect rising sea levels.
The Fish Report is focusing on the California Delta over the next several weeks. Start with the history article, then be sure to check out Disrupting the Delta Food Web and A Happy Accident: Restoration at Liberty Island for a look at how the Delta’s past has shaped its present, and what farmers, fisheries managers, conservationists and others are doing to protect the Delta’s future.