VI. C. 1. Types of Modification |
Dredging is typically conducted to provide and maintain adequate depth for vessels in navigation channels, slips, and berthing areas. Depending upon the location and proposed depth, dredging may convert intertidal and shallow subtidal habitat to deepwater habitat (Haring 2000). Dredging and disposal are regulated through state and federal permit systems. Dredged material containing low levels of contaminants may be disposed at designated open-water disposal sites under the Puget Sound Dredged Disposal Analysis (PSDDA) program. Dredged material with higher contaminant loads must be treated or disposed at a confined facility. Confined disposal sites are generally located in upland (i.e., landfill) areas.
Large filling projects are not as common in Puget Sound today. Historically, filling of nearshore areas was conducted to create new upland areas for development, which frequently resulted in loss of wetlands, beaches, and other habitat. However, small-scale filling of nearshore areas waterward of the MHHW line may occur during shoreline armoring, which buries nearshore habitat. Modern filling projects usually are conducted to create or restore habitat (i.e., beach nourishment; see section above) (Zelo and Shipman 2000), or to cap contaminated sediment.
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