Restoring Estuarine Processes to the Nisqually Delta

During the late 1800s and early 1900s, large areas of the Nisqually delta and estuary in south Puget Sound were, diked, ditched, and drained to convert salt marshes to pasture and crop land. More than 50 percent of the historic intertidal emergent marsh habitat was lost, leading to a dramatic decrease in estuarine habitat for various fish and wildlife species, some of which are now federally listed under the Endangered Species Act. In 1996, the Nisqually Indian Tribe, as a part of its efforts to recover salmon through habitat restoration, took the first step to reverse this damage by breaching a 160-foot section of dike and restoring tidal influence to am 11-acre site.

In 2002, the Tribe further restored full and unimpeded tidal influence to that site, and to an additional 39 acres by removing all dikes that surrounded the two areas. The goal is to restore estuarine functions by reestablishing estuarine processes rather than by restoring individual physical, biological, and chemical elements of the estuary. We believe that passive restoration will recreate estuarine functions over time if processes are restored, and if the appropriate tidal action, water quantity, water quality, sediment, flora, and fauna are available.

To evaluate the success of this strategy, we are monitoring several elements, including hydrology, water quality, changes in micro-topography (accretion and erosion), changes in vegetation, and use of the site by aquatic and (with the Nisqually Reach Nature Center) avian wildlife.

In the future, the Tribe plans to remove dikes that surround an additional 110 acres of estuary land.

Abbreviated from a paper by Florian Leischner and Jeanette Dorner (Natural Resources Department, Nisqually Indian Tribe), and Bob Wiltermood and Joanne Bartlett (Wiltermood Associates, Inc., Port Orchard WA).