Presentation Abstract

Lone Tree Creek is located on the Swinomish Indian Tribal Community (SITC) Reservation. The creek’s watershed includes pocket estuary habitat, discharges over shellfish beds, an important resource for the Swinomish People, and flows into northern Skagit Bay. In 2006, extensive creek restoration replaced culverts, restored tidal influence to the pocket estuary, and planted riparian buffers, successfully restoring rearing habitat for juvenile Chinook salmon. Beyond fish habitat benefits, SITC wanted to assess long-term restoration effects on creek water quality and its associated pocket estuary, lagoon and bay. Water quality monitoring for conventional parameters and bacteria spanned 1997-2016 (10 years pre- and post-restoration). The primary creek monitoring site was moved upstream following restoration. To maximize available data for analysis, pre-restoration data was from the initial monitoring site (LON1) and post-restoration data from the current monitoring site (LON10). Data were analyzed using the nonparametric Wilcox signed-rank test and a pseudomedian was used to estimate the difference in pre and post-restoration medians. Results at all sites showed significant post-restoration increases in dissolved oxygen (DO). Creek daily average water level and discharge were also significantly higher at LON10 (post-restoration) compared to LON1 (pre-restoration). Since higher discharge is correlated with higher DO, pre- and post-restoration water quality was also compared at LON1 only to help determine whether changes might be attributed to restoration or to monitoring site location. Though using LON1 data only required a smaller sample size, there was significantly higher DO post-restoration at this location. The restoration therefore appears to have improved creek DO, either independent of, or as a result of increased water flow. The Lone Tree Creek watershed is influenced by run-off and these data suggest that water quality will be influenced by discharge in the ecosystem. Such findings provide considerations for future restoration efforts and have implications for climate change effects.

Session Title

Water Quality and Hydrodynamics

Keywords

Water quality, Lone Tree watershed, Swinomish

Conference Track

SSE1: Habitat Restoration and Protection

Conference Name

Salish Sea Ecosystem Conference (Seattle, WA : 2018)

Document Type

Event

SSEC Identifier

SSE1-412

Start Date

4-4-2018 2:15 PM

End Date

4-4-2018 2:30 PM

Type of Presentation

Oral

Contributing Repository

Digital content made available by University Archives, Heritage Resources, Western Libraries, Western Washington University.

Geographic Coverage

Salish Sea (B.C. and Wash.)

Rights

This resource is displayed for educational purposes only and may be subject to U.S. and international copyright laws. For more information about rights or obtaining copies of this resource, please contact University Archives, Heritage Resources, Western Libraries, Western Washington University, Bellingham, WA 98225-9103, USA (360-650-7534; heritage.resources@wwu.edu) and refer to the collection name and identifier. Any materials cited must be attributed to the Salish Sea Ecosystem Conference Records, University Archives, Heritage Resources, Western Libraries, Western Washington University.

Type

text

Language

English

Format

application/pdf

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Apr 4th, 2:15 PM Apr 4th, 2:30 PM

Water quality effects of fish habitat restoration at Lone Tree Creek

Lone Tree Creek is located on the Swinomish Indian Tribal Community (SITC) Reservation. The creek’s watershed includes pocket estuary habitat, discharges over shellfish beds, an important resource for the Swinomish People, and flows into northern Skagit Bay. In 2006, extensive creek restoration replaced culverts, restored tidal influence to the pocket estuary, and planted riparian buffers, successfully restoring rearing habitat for juvenile Chinook salmon. Beyond fish habitat benefits, SITC wanted to assess long-term restoration effects on creek water quality and its associated pocket estuary, lagoon and bay. Water quality monitoring for conventional parameters and bacteria spanned 1997-2016 (10 years pre- and post-restoration). The primary creek monitoring site was moved upstream following restoration. To maximize available data for analysis, pre-restoration data was from the initial monitoring site (LON1) and post-restoration data from the current monitoring site (LON10). Data were analyzed using the nonparametric Wilcox signed-rank test and a pseudomedian was used to estimate the difference in pre and post-restoration medians. Results at all sites showed significant post-restoration increases in dissolved oxygen (DO). Creek daily average water level and discharge were also significantly higher at LON10 (post-restoration) compared to LON1 (pre-restoration). Since higher discharge is correlated with higher DO, pre- and post-restoration water quality was also compared at LON1 only to help determine whether changes might be attributed to restoration or to monitoring site location. Though using LON1 data only required a smaller sample size, there was significantly higher DO post-restoration at this location. The restoration therefore appears to have improved creek DO, either independent of, or as a result of increased water flow. The Lone Tree Creek watershed is influenced by run-off and these data suggest that water quality will be influenced by discharge in the ecosystem. Such findings provide considerations for future restoration efforts and have implications for climate change effects.