Publication Date

Spring 2025

Degree Type

Thesis

Degree Name

Master of Science (MS)

Department

Environmental Studies

Advisor

Lynne Trulio; Metha Klock; Rachel O'Malley

Abstract

Streams and their riparian zones in the San Francisco Bay Area have been degraded, severely harming salmonid populations in the region. Ecological restoration is a common approach to return stream function. Such restoration projects vary widely in intensity, from low-impact vegetation removal/planting to highly engineered projects involving structures and grading. This research investigated the effectiveness of streams restored using engineered versus non-engineered solutions in supporting salmonid habitat viability in San Francisco Bay Area streams. Fourteen streams, seven from each of the two types of restoration, were sampled in the wet and dry season in 2024, three times each season. Data on temperature, dissolved oxygen, pH, nitrite, turbidity, canopy density, vegetation species richness/diversity, stream depth, and width were collected and analyzed with a range of descriptive and inferential statistics. Results showed that none of the parameters differed between the two restoration types in the dry season and differed only with respect to temperature in the wet season. Riparian vegetation species diversity did differ between engineered and non-engineered sites in either season. In both seasons, all restored streams tended to meet established salmonid quality thresholds. This study indicated that: 1) both engineered and non-engineered restoration sites were able to, under appropriate conditions, meet salmonid habitat water quality targets and 2) restoration designers should only perform engineered projects when absolutely necessary.

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