Dredging Study

Upper Newport Bay
	Introduction
	Do's and Don'ts
	History
	The Robinsons
	Habitats
	Watershed
	Dredging Project

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Background Information on Dredging Project

Upper Newport Bay is an estuary - a place where fresh and salt water mix. The fresh water enters the Upper Bay primarily via San Diego Creek in the north east corner of the Bay at Jamboree Blvd. and meets the tidal flow of the Pacific Ocean, entering from the Lower Bay at Pacific Coast Hwy. This tidal flooding and mixing is one of the main reasons for the abundance of the salt marsh vegetation that provides food and shelter for a diversity of wildlife including the largest population of the endangered Clapper Rail in the United States.

Historically only about 15 square miles of land drained into the bay via San Diego Creek. However, the drainage area was increased to about 118 square miles by the channelization of San Diego Creek as part of a major flood control project completed in 1968. One year later San Diego Creek, swollen by heavy rains, overwhelmed Upper Newport Bay and destroyed the salt works that had occupied the north east corner of the Bay since 1934 and poured hundreds of thousands of tons of sediment into the Bay. Every year more and more sediment is carried into the Bay. Several dredging projects have taken place since then, but without drastic action the Bay will eventually fill completely with sediment and become a meadow.

Remains of the Old Salt Dike as seen from Back Bay Drive.

The US Army Corps of Engineers, in cooperation with federal, local and state agencies studied ways in which to restore and maintain tidal movement in the Bay. A final report, the Upper Newport Bay Ecosystem Restoration Feasibility Study Final Report, was issued by the Corps in September 2000. The study initially considered six alternatives. Alternatives 2 and 3 involved the removal of both Skimmer Island and Tern Island in creating a bigger sediment catch basin in the north east corner of the Bay. These alternatives were dismissed during the study process as being too detrimental to the endangered California Least Tern population. The other four alternatives were studied in detail and Alternative 6 was finally recommended. In this alternative, Tern Island remains and Skimmer Island is removed and a new island is created downstream of the Old Salt Dike. (In the Corps report Tern Island is referred to as the "hot-dog shaped tern island" and Skimmer Island is referred to as the "kidney shaped tern island". Care is needed to distinguish between "Tern Island" and "a tern island" in conversations about island removal.)

Tern Island with Skimmer Island behind it.

The authorized project, which began in October, 2005, involves an initial dredging and restoration effort to be funded 65% by federal money and 35% by local money. Subsequent sediment monitoring and maintenance dredging will be paid exclusively by local funds. The initial project, including detailed plans and specifications, will cost roughly $38.5 million. The $13.5 million local share of this has already been funded with State of California Proposition 12 money. As of July 2008, Congress had only funded about half of the $25 million federal share. And total cost has escalated to about $45 million.

The Alternative 6 plan (see map) involves:

Expanding and deepening two sediment collection basins at the north end of the Bay.

Removal of Skimmer Island from the upper basin and creation of a replacement island on the north side of the lower basin.

Restoration of side channels around New Island, Middle Island, and Shellmaker Island.

Creation of new wetlands at Shellmaker Island and Northstar Beach and in the northwest corner of the Bay.

Approximately 2.1 million cubic yards of material will be dredged. As a result, the expected interval at which maintenance dredging is needed will be 21 years.