Pre-analysis per-gauge facts (D78, 2026-05-17): - Boxley: first 1.96 ft @ 00:00; max 1.96 ft @ 00:00 (first reading = max, pure recession); last 1.89 ft @ 23:30. Net -0.07 ft. - Ponca: first 82.8 cfs @ 00:00; max 82.8 cfs @ 00:00 (pure recession); last 75.2 cfs @ 23:30. Net -7.6 cfs. - Pruitt: first 3.57 ft / 79.3 cfs @ 00:00; max 3.58 ft / 81.1 cfs @ 00:30; last 3.50 ft / 67.4 cfs @ 23:30. Intraday low 3.50/67.4. Net -0.07 ft / -11.9 cfs. - St. Joe: first 3.63 ft / 242 cfs @ 00:00; max 3.65 ft / 248 cfs @ 00:15 (also recurred 02:45); last 3.56 ft / 222 cfs @ 22:45. Intraday low 3.55/219. Net -0.07 ft / -20 cfs. - Harriet: first 3.81 ft / 300 cfs @ 00:00; max 3.81 ft / 300 cfs @ 00:00 (pure recession); last 3.74 ft / 265 cfs @ 22:45. Net -0.07 ft / -35 cfs. - Richland: first 1.31 ft @ 00:00; max 1.31 ft @ 00:00 (pure recession); last 1.24 ft @ 23:00. Net -0.07 ft. - Bear Cr: first 2.09 ft / 13.7 cfs @ 00:00; max 2.10 ft / 14.1 cfs @ 01:00 (minor noise); last 2.08 ft / 13.2 cfs @ 23:15. Net -0.01 ft / -0.5 cfs.
1. PRECIPITATION SUMMARY: Zero rainfall basin-wide. All 37 HUC12s record 0.000" 24-hr QPE. All gauge zones at 0.000". A completely dry day — the first such day in several weeks. Antecedent 7-day values are still elevated in the Bear Cr / Harriet / lower-watershed zones from the D77 lower-watershed convective scatter (Hickory Cr 0.407", Brush Cr 0.462", Bear Cr Outlet 0.472", Headwaters Bear 0.471", Davis Cr 0.412") but those signals never produced gauge response.
2. GAUGE RESPONSES: All gauges in pure recession. Uniform ~-0.07 ft drop across Boxley, Pruitt, St. Joe, Harriet, and Richland over ~23 hours — striking consistency. Discharge falls: Ponca -7.6 cfs, Pruitt -11.9 cfs, St. Joe -20 cfs, Harriet -35 cfs. Bear Cr essentially flat (-0.01 ft).
New study-period lows established at every gauge: - Boxley 1.89 ft (prior low 1.96, D77) - Ponca 75.2 cfs (prior 82.8, D77) - Pruitt 3.50 ft / 67.4 cfs (prior 3.55/75.8, D77) - St. Joe 3.55 ft / 219 cfs (prior 3.62/239, D77) - Harriet 3.74 ft / 265 cfs (prior 3.82/305, D77) - Richland 1.24 ft (prior 1.32, D77) - Bear Cr 2.08 ft / 13.2 cfs (prior 2.10/13.7, D77)
Pruitt now below 100 cfs for two consecutive days — firmly in Too Low range (<100 cfs). St. Joe at 219 cfs is approaching the bottom of its Optimal range (200 cfs threshold).
3. RAINFALL-RESPONSE PAIRS: None — zero QPE today.
4. DOWNSTREAM PROPAGATION: N/A — no event today. However, the synchronized -0.07 ft drop across all five mainstem-chain gauges within the same 24-hour window is itself a useful baseflow-recession observation: when no event is propagating, all mainstem gauges decline at roughly parallel rates in height terms (though discharge rates scale with channel size, as expected).
5. MULTI-DAY EVENTS: Today is Day 7 post-Event-10-peak (Harriet primary D73 03:00 → today D78). Recession is now in deep groundwater-baseflow phase. Comparing recession rates to Event-9 sequence:
The recession is asymptotic, not floored. Each successive day shows smaller absolute decline (geometric decay), but a new low is set every day. This is the deepest baseflow observed in 78 days of study.
6. ANOMALIES OR SURPRISES: - Bear Creek decoupling: Bear Cr held essentially flat today (-0.01 ft / -0.5 cfs) while all other gauges dropped ~-0.07 ft. Bear Cr has been the slowest-recessing gauge for three consecutive days. Possible explanation: Bear Cr's antecedent 7-day (0.47") is the second-highest in its zone group thanks to the D77 lower-watershed convective scatter, which delivered 0.108" zone-avg there. Subsurface storage from that pulse may be sustaining baseflow even though no surface response occurred. This is the first empirical evidence that sub-threshold rainfall provides measurable subsurface baseflow support without triggering gauge rise. Worth flagging for further observation. - The Pruitt-zone 7-day (0.139-0.206") is the lowest in the basin — and Pruitt has the steepest absolute % decline in discharge. Consistent with the Bear Cr observation: subsurface antecedent matters more than visible event response for late-recession baseflow. - The St. Joe height noise at 3.65 ft @ 00:15 and 02:45 (above the otherwise-monotonic descent) appears to be the same kind of measurement noise pattern seen previously, not a real pulse — no corresponding upstream signal and no QPE.