White, J.S., Garvin, L.E.S., Wallick, J.R., Maher, A., and Bervid, H., 2023, Comparison of environmental flow recommendations for the Willamette Basin Sustainable Rivers Program, WYs 2008-2022: U.S. Geological Survey data release, https://doi.org/10.5066/P9A46G20.
The Willamette River Basin, Oregon is one of several a demonstration sites within the SRP, a national partnership between the US Army Corps of Engineers (UASCE) and The Nature Conservancy (TNC), to provide ecologically sustainable flows downstream of dams while still meeting human needs and congressionally authorized purposes (Warner, 2014). The SRP is an adaptively managed environmental flow program, whereby initial flow recommendations are made using the best available knowledge of flow and ecological relations, and then subsequently refined by through monitoring, evaluation, and stakeholder input (Higgins and others, 2011; Warner and others, 2014). As part of the Willamette SRP, stakeholder workshops were convened between 2007-2012, which culminated in stakeholder-defined environmental flow recommendations for the Middle Fork Willamette, McKenzie, and Santiam River Basins (Gregory and others, 2007; Risley and others, 2010; Bach and others, 2013, respectively). Within each basin, the major rivers below USACE dams were divided into hydrologically distinct reaches, and stakeholders developed reach-specific environmental flow recommendations. Each environmental flow recommendation consists of a flow target linked with a specific element of the annual hydrograph (for example, the annual peak flow) and an associated ecological objective (see Wallick and others, 2018 for detailed explanation). Altogether, the Willamette SRP consisted of 63 environmental flow recommendations encompassing a diversity of hydrological conditions and ecosystem processes. From 2010 thru 2015, USACE prepared a series of studies investigating how environmental flow recommendations could be operationalized. The goal was to show feasibility of implementing select SRP flow recommendations while not violating water management constraints or increasing risk levels. In July of 2015, USACE water control manuals were updated to reflect the most attainable of the SRP environmental flow recommendations, but do not include all 63 of the stakeholder-generated environmental flow recommendations. USACE dam operations to support the SRP environmental flow recommendations reflect a wide range of considerations, priorities, and hydrologic conditions; hence conditions conducive to implementation of SRP environmental recommendations may not be present each year. The Willamette SRP is in the implementation phase whereby flows are monitored to assist stakeholders, USACE, and TNC in adaptively managing the environmental flow recommendations (Higgins and others, 2011; Wallick and others, 2018). The first step in the monitoring and evaluation process is implementation monitoring, whereby stakeholder-defined flow recommendations are compared against actual measured flows to determine the degree to which flow targets for each recommendation were achieved. Implementation monitoring provides the foundation for effectiveness monitoring, which determines whether flow targets are successful at achieving stated ecological goals (Higgins and others, 2011). This data release supports adaptive management of the Willamette SRP by providing summary information describing stakeholder-defined flow recommendations and how measured streamflow compares to those recommendations for water years 2008-2022. This data release includes text files (comma separated values) describing three components needed to evaluate SRP implementation: a) text describing the flow recommendations, b) metrics for each flow recommendation, and c) results from a comparison of streamflow data with flow recommendations. Additionally, graphs are provided which compare measured streamflows with SRP targets for each reach. The information compiled in this data release is also intended to streamline future implementation monitoring for the Willamette SRP. The first component is a spreadsheet compilation of all 63 stakeholder-defined environmental flow recommendations (WillametteSRP_flow-recs-text.csv) as originally reported in three reports describing outcomes of stakeholder workshops held in the Middle Fork Willamette, McKenzie, and Santiam Basins (Gregory and others, 2007; Risley and others, 2010; Bach and others, 2013, respectively). This compilation of flow recommendations uses the exact language for each flow recommendation from the various stakeholder workshop reports. Secondly, each of the 63 SRP flow recommendations were summarized into machine-readable, quantifiable flow metrics (WillametteSRP_flow-recs-metrics.csv) and associated with corresponding USGS streamflow gaging stations where each metric should be applied. Thirdly, the flow metrics were compared with USGS streamflow gaging data, and the results (WillametteSRP_flow-recs-results.csv) of these analyses are provided to document the degree to which each flow recommendation was achieved in the period of 2008-2022. Finally, a series of graphs were produced to compare measured streamflow at each reach where SRP environmental flow recommendations were developed, with SRP flow targets for that reach; graphs for each water year for the period of 2008-2022, provide visual depiction of measured flow and SRP targets.
