Ecological Responses to Streamflow: Tracking the Outcomes of Water Transactions

The Columbia Basin Water Transactions Program (CBWTP) was started in 2002 to address a chronic regional challenge. As a result of legal water withdrawals during the peak growing season, stretches of many streams and rivers run low – and sometimes dry – with significant consequences for imperiled salmon, steelhead, trout and other biota. Using permanent acquisitions, leases, investments in efficiency and other incentive-based approaches, the CBWTP supports program partners in Oregon, Washington, Idaho and Montana to assist landowners who wish to restore flows to existing habitat. The CBWTP is managed by the National Fish and Wildlife Foundation, a not-for-profit organization dedicated to the conservation of fish and wildlife, working in partnership with the Bonneville Power Administration.  Over the life of projects that the CBWTP has supported to date, about 5.28 million acre-feet of water is committed to enhancing stream flows throughout the Columbia River Basin. To assess the effectiveness of flow restoration on improving stream habitat for salmonid populations, CBWTP is implementing a four-tiered nested monitoring program.  The first tier of monitoring applies to all investments and ensures compliance with the terms of transaction. The second tier of monitoring verifies that the quantity of flow secured through water transactions remains in the stream through the intended reach.  The third tier of monitoring seeks to determine the thresholds at which changes in habitat can be detected as a result of flow restoration.  This tier will utilize indicators of ecological function to track changes in habitat conditions.  The fourth and most intensive monitoring tier aims to quantify relationships between changes in ecological function and flow restoration.  This tier will be integrated within broad collaborative partnerships and will focus on several select streams throughout the Columbia River Basin with an initial pilot effort in the Methow Basin.  Annual monitoring results from each of the tiers will be synthesized to track ecological outcomes of water transactions, to shape strategies and priority areas for future transactions and stream flow restoration, and to contribute to the growing movement to secure environmental flows.