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Trinity County-backed winter-variable flow plan explained; county won 4-day notice and outreach pledges
Summary
TRP staff presented the county'backed winter-variable-flow proposal approved by the Trinity Management Council. The plan includes a "synchronized storm pulse" window with a 4-day advance notice requirement and an elevated-baseflow period. Board members and residents pressed for outreach and clarification about when the plan would take effect.
Patrick Flynn, environmental compliance specialist with Trinity County Natural Resources and coordinator for the Trinity Restoration Program flow work group, briefed the board on the county's winter-variable-flow proposal (approved Sept. 18 by the Trinity Management Council) and how it would be implemented in water year 2025.
Flynn described two parts of the winter action: a flow synchronization period (Dec. 15'Feb. 14) where a forecast trigger (45,100 cubic feet per second at the North Fork Trinity gauge) could cause a synchronized storm pulse that releases up to 60,000 acre-feet and peaks at 65,100 cfs; and an elevated-baseflow (wet-season flood) period (Feb. 15'Apr. 14) driven by the B120 forecast tool that could add between 60,000 and 180,000 acre-feet depending on forecasts. Flynn noted the county successfully negotiated several accommodations into the TMC-approved proposal, including a maximum of one synchronization event during the Dec. 15'Feb. 14 window, a request to minimize rapid receding (abrupt decreases after a peak), and a county-requested minimum of four days advance notice before synchronization releases.
Flynn said the Bureau of Reclamation had not yet signed the related environmental assessment as of Dec. 3; Reclamation leadership had requested further tribal engagement and the county expected resolution within days. The presenter reviewed sample hydrograph shapes tied to different trigger timings, explained that synchronized releases are intended to piggyback on natural storm flows rather than fully mimic a natural hydrograph, and walked the board through how outreach would be handled (mailings to riverfront landowners, TRP and Bureau of Reclamation press releases and social media posts, sandwich-board signage at access points, and an email/Google-group subscription feed for release orders).
Board members asked about the probability of a synchronization event under the proposed rule-set (work-group analysis suggested it would have occurred about six times in a 14-year span from 2005'2019), and about whether recent early-season storms would have triggered releases; Flynn said an earlier November storm would have triggered under the forecasting tool but the synchronization period begins Dec. 15. The board requested continued outreach and asked staff to post notices at river access locations and to coordinate signage in Lewiston.
Patrick Flynn (first reference included role). Kiana and other TRP staff were listed as backups for questions. Flynn and TRP staff explained the technical forecasting tools and outreach commitments; no formal county vote or policy change was taken at the meeting.
