Did You Know
This picture, taken near the Delta Science Center, at Big Break Regional Shoreline, shows the remains of a very old clamshell dredge. Clamshell dredges were used to build many levees throughout California, especially in the Delta. These "mechanical cable excavators" use a 2-sided, hinged bucket (the "clamshell") attached to the dredge crane with cables. Clamshell dredges are still used widely throughout the Delta today.
Wetlands are areas covered with water all or part of the time. The many wetlands throughout the Delta help protect and enhance water quality, wildlife, and human safety and welfare. Wetlands filter runoff water, fertilizers, pesticides and more, protecting drinking water. Wetlands provide essential habitat for 90% of the fish species consumed by humans, as well as a multitude of endangered species, and a myriad of other plants and animals, especially invertebrates and birds.
A levee is a barrier, or wall, of dirt constructed to contain the flow of water and help keep out tidal saltwater. Levees have been built throughout the Delta, beginning 150 years ago with "shoestring" levees constructed manually by shovel. Around 1900, the clamshell dredge greatly eased levee projects. Today, over 1100 miles of levees protect Delta agriculture, communities and freshwater from flood and saltwater intrusion.
The Delta consists of 52 major islands and approximately 1000 miles of waterways. Some of the waterways are deep water channels that allow oceangoing ships to sail up the Delta as far as the ports of Stockton and Sacramento. Although some Delta islands are accessible only by boat, more than 50 bridges connect most of the islands.
International waterways, like the Delta, are especially rich gateways and stongholds for non-native, or exoctic plants. Exoctic plants compete with native plants for resources and can outcompete plants that are food supplies for fish and other animals. Exoctic plants in Delta have been transported from local and faraway gardens by the Delta winds, Delta currents, wildlife and residents. Ships from around the world have inadvertently discharged seeds or plant material, allowing exoctic plants to gain a local beachhead in the Delta. The Pyracantha (pictured) is an exoctic plant that is now common. In wetlands that are being restored, plants like the Pyracantha are being replaced with native species.
Riprap is used to protect the banks of rivers and levees in the Delta from erosion. Riprap is often made from granite boulders or recycled concrete rubble. Although it is quick and effective to place, riprap is poor habitat for wildlife.
Big Break Regional Shoreline was formed by a levee break approximately 80 years ago that flooded an asparagus farm. Most of the shoeline has returned to its natural state of rich riverside wetlands. Now subject to tidal action, Big Break's waters rise and fall, distributing nutrients and sediments, and keeping the wetlands lush, green and vibrant.