Implementation of Lower San Joaquin River Flow Objectives Yongxuan Gao Timothy Nelson William Anderson CWEMF Annual Meeting 2019 Folsom, California

Purpose of this Presentation Describe quantitative methods for adaptive implementation of flow objectives in the Lower San Joaquin River (LSJR) watershed Provide hypothetical examples to demonstrate adaptive implementation methods on the Stanislaus River, a tributary to the Lower San Joaquin River

Presentation Outline Background of the Lower San Joaquin River (LSJR) flow objectives Methods for Adaptive implementation Hypothetical examples of adaptive implementation

Background The State Water Board adopted the Amendments to the Water Quality Control Plan for the San Francisco Bay/Sacramento-San Joaquin Delta Estuary (Bay-Delta Plan) on December 12, 2018 The flow amendments are not self-implementing and will require a future water right or water quality proceeding to assign responsibility for implementation Stakeholders are currently discussing Voluntary Agreements that include flow and non-flow measures like habitat restoration as an alternative form of meeting the fish and wildlife objectives This presentation does not presuppose how the objectives will ultimately be met but only illustrates how adaptive implementation can be modeled

Flow Objectives on the LSJR (Feb – Jun) Narrative flow objective: maintain inflow conditions to support natural production of viable native San Joaquin River Watershed fish populations Numeric flow objective: maintain 40% of unimpaired flow (UIF), with an allowed adaptive range between 30% - 50%, inclusive, from each of the Stanislaus, Tuolumne, and Merced Rivers from February through June

Adaptive Implementation A feature of the LSJR program of implementation that allows for adjustment of the required percentage of unimpaired flow in specified ways to improve the functions of those flows and better achieve the water quality objective

Adaptive Implementation Methods The required percentage of unimpaired flow for February through June may be adjusted to any value between 30% and 50%, inclusive may be managed as a total volume of water and released on an adaptive schedule during Feb through Jun: total volume of water must be at least equal to the volume of water that would be released may be delayed until after June to prevent adverse effects to fisheries: only allowed when the unimpaired flow requirement is greater than 30%, and only a certain percentage of the flow can be shifted Vernalis base flow for Feb through Jun may be adjusted to any value between 800 and 1,200 cfs, inclusive

Example 1- Variable Quantity Adjusted from 40% to a Different % Adaptive Method a)

Example 2- Simple Flow Shaping Adaptive Method b)

Water Year 2002 Year Type Dry TAF Shaped 25 Feb (% of UIF) 30 40 Mar (% of UIF) Apr (% of UIF) 46 May (% of UIF) Jun (% of UIF)

Water Year 2002 Year Type Dry TAF Shaped 25 Feb (% of UIF) 30 40 Mar (% of UIF) Apr (% of UIF) 46 May (% of UIF) Jun (% of UIF)

Example 3- Flow Shaping and Shifting Adaptive Method c)

Floodplain Activation Water Year 1999 Year Type AN TAF Shaped 29 TAF Shifted 35 Feb (% of UIF) 30 40 Mar (% of UIF) Apr (% of UIF) 45 May (% of UIF) Jun (% of UIF) 25 Floodplain Activation

Water Year 1999 Year Type AN TAF Shaped 29 TAF Shifted 35 Feb (% of UIF) 30 40 Mar (% of UIF) Apr (% of UIF) 45 May (% of UIF) Jun (% of UIF) 25

Thank you Questions?