This document reports on findings, conclusions and recommendations derived from scientific literature and knowledge regarding the effectiveness of tide gate removal or upgrade in improving conditions for Oregon’s native migratory fish species, particularly salmonids, and other plant and animal species that utilize estuarine ecosystems. The project was commissioned by the Oregon Watershed Enhancement Board (OWEB) to foster better understanding of the effectiveness of their past investments in estuary habitat restoration involving tide gates, and to aid in targeting future investments. This will be especially important because many less-complicated projects (e.g. those on public land, smaller, single-action projects, those with consensus on land use) have already been completed, and restoration efforts are becoming increasingly complex and resource intensive. Additionally, restoration actions and benefits can vary considerably according to local conditions. Thus, key questions going forward involve project prioritization and design to achieve maximum return on investments in an environment where demand for projects exceeds available resources. Users of this information may include applicants submitting tide gate and estuary restoration proposals to OWEB, reviewers of these proposals, other OWEB staff, and the OWEB Board of Directors.