Tidal wetlands at Ni-les’tun, Year 9 after restoration

By Laura Brophy

April 2021

The Estuary Technical Group (ETG) monitors tidal wetland restoration projects to track their effectiveness, glean "lessons learned" to guide future restoration work, and generally improve our understanding of estuarine ecology. On the southern Oregon coast, ETG, Oregon State University, and the Confederated Tribes of Siletz Indians (CTSI) co-lead monitoring at the Ni-les'tun Tidal Wetland Restoration project at Bandon Marsh National Wildlife Refuge. Along with the Southern Flow Corridor project in Tillamook County (also monitored by ETG, OSU and CTSI), Ni-les'tun is one of the largest tidal wetland restoration projects on the Oregon coast. This project on the lower Coquille River has restored over 166 hectares (411 acres) of tidal marsh and tidal swamp that had previously been diked and cut off from the estuary for many decades. You can watch a very interesting video about the restoration at https://youtu.be/Dgyta4TDaEc.

The main work of restoration at Ni-les'tun – removal of dikes and other tidal flow barriers, and excavation of a tidal channel network -- was completed in 2011. During 2013-2015, many more tidal channels were added. In the nine years since the dikes were removed, native salt marsh vegetation has spread throughout the site, demonstrating that brackish tidal flows and the associated natural processes have been re-established. ETG and CTSI are also monitoring fish use of the site, water characteristics such as salinity and water temperature, channel characteristics, and soils. Look for more results in future ETG news!

The Ni-les'tun tidal wetland restoration site (center of photo) is located just north of the city of Bandon, Oregon along the lower Coquille River. (Imagery ©2021 Google)

Before restoration in 2003, the Ni-les'tun site was diked and used for agriculture, primarily cattle pasture. Note the Highway 101 bridge in the distant background – this is a big site! (Photo by Laura Brophy.)

To bring the tides back into the Ni-les'tun restoration site in 2011, contractors excavated openings through the site's perimeter dike. (Photo by USFWS.)

During restoration activities in 2010-2011, ground crews dug miles of tidal channels to carry the incoming tides throughout the site. (Photo by Roy W. Lowe, USFWS.)

In 2020, after 9 years of recovery, Ni-les'tun has abundant growth of native tidal wetland plants, such as salt-tolerant pickleweed (Sarcocornia perennis)...

...and seaside arrowgrass (Triglochin maritima). (Photos by Laura Brophy.)

During the 9 years since tides came back to Ni-les'tun, extensive meadows of Lyngbye's sedge (Carex lyngbyei) have become established. The lush growth of this sedge captures large amounts of carbon from the atmosphere, much of which is stored in the soil, helping to mitigate climate change. (Photo by Laura Brophy.)

Beaver have built an intertidal dam on Fahys Creek on the north edge of the Ni-les'tun restoration site. The dam is visible only at low tide (left); ....

...as the tide rises, the dam is inundated (right). Intertidal beaver dams are increasingly recognized as providing important habitat for young salmon. (Photos by Laura Brophy.)

ETG's monitoring at Ni-les'tun is funded primarily by the Oregon Watershed Enhancement Board (OWEB), with in-kind contributions from many partners and volunteers. We are grateful for their generosity and for the opportunity to study the results of restoration at Ni-les'tun!

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