Day 20 (2026-03-20) — Continued Dry Recession, Day 9 Post-Event 3 Peak
Zero precipitation across the entire watershed for the 5th consecutive day. All 37 HUC12s report 0.0" 24-hour totals. 7-day antecedent moisture is unchanged from Day 19, remaining at the driest levels observed in the study: 0.14-0.56" across HUC12s, with most sub-basins below 0.3".
All gauges continue monotonic recession with no rainfall-driven responses. End-of-day status:
| Gauge | Day 19 EOD | Day 20 EOD | Change (cfs) | 24-hr Rate (%/hr) | Recreational Status |
|---|---|---|---|---|---|
| Ponca | 136 cfs | 129 cfs | -7 | ~0.21%/hr | Too Low (<150) |
| Pruitt | 177 cfs | 153 cfs | -24 | ~0.56%/hr | Low but Floatable (100-200) |
| St. Joe | 394 cfs | 353 cfs | -41 | ~0.43%/hr | Optimal (200-8000) |
| Harriet | 473 cfs | 425 cfs | -48 | ~0.42%/hr | Optimal (200-9370) |
Height observations (more reliable per local knowledge): - Boxley: 2.21→2.16 ft (-0.05 ft). New study low. - Pruitt: 4.05→3.96 ft (-0.09 ft). Dropped below 4.00 ft for first time in study (~10:30 CST). New study low. - St. Joe: 4.13→4.02 ft (-0.11 ft). New study low. - Harriet: 4.12→4.04 ft (-0.08 ft). New study low. - Richland: 1.20→1.16 ft (-0.04 ft). New study low. - Bear Creek: 2.40→2.39 ft (-0.01 ft), discharge 11.3→10.6 cfs. New study low.
None — no precipitation occurred.
No event propagation. However, the recession data continues to provide useful information about baseflow dynamics.
Extended dry recession analysis (Day 20 — 9 days post Event 3 peak):
Recession rate evolution over the last 3 days:
| Gauge | Day 18 Rate | Day 19 Rate | Day 20 Rate | Trend |
|---|---|---|---|---|
| Ponca | ~0.27%/hr | ~0.27%/hr | ~0.21%/hr | Decelerating — first sign of approaching baseflow |
| Pruitt | ~0.33%/hr | ~0.56%/hr | ~0.56%/hr | Steady — no deceleration yet at this noisy gauge |
| St. Joe | ~0.70%/hr | ~0.37%/hr | ~0.43%/hr | Fluctuating around 0.4% — baseflow transition |
| Harriet | ~0.70%/hr | ~0.49%/hr | ~0.42%/hr | Continuing to decelerate |
Key observation — Ponca deceleration: Ponca recession rate dropped from 0.27%/hr (Days 18-19) to 0.21%/hr today. At 129 cfs end-of-day, this is the first clear sign of recession deceleration at this gauge. If rate continues to slow at this pace, Ponca may stabilize around 120-125 cfs within 2-3 more dry days.
Pruitt continues anomalously fast recession. At 153 cfs, Pruitt is now reading only 24 cfs above Ponca (129 cfs) despite draining an additional 123 km² (Cove Creek + Hoskin Creek). This Pruitt-Ponca gain of only 24 cfs (19% gain) is the lowest ratio observed in the study and is consistent with the local knowledge about channel scouring directing flow to river right, away from the gauge at river left. At low stages, this gauge artifact appears to grow.
Pruitt-Ponca gain tracking (extended):
| Day | Pruitt CFS | Ponca CFS | Gain (cfs) | Gain (%) |
|---|---|---|---|---|
| Day 18 | 206 | 145 | 61 | 42% |
| Day 19 | 177 | 136 | 41 | 30% |
| Day 20 | 153 | 129 | 24 | 19% |
The gain percentage is declining as flows drop, which is consistent with the local knowledge that the Pruitt gauge reads artificially low at low stages. At moderate-to-high flows (Events 1-3), the Pruitt-Ponca gain was 50-80+ cfs. The shrinking gain at low flows is almost certainly a measurement artifact, not a real hydrological change.
Ponca has crossed below the "Too Low" threshold (<150 cfs). This is the first time Ponca has been in "Too Low" during the study. It crossed below 150 on Day 19 (around 15:45 CST at 138 cfs) and has continued declining.
Pruitt approaching "Too Low." At 148 cfs minimum today (19:45 CST), Pruitt briefly touched just below 150. With current recession trajectory, Pruitt could cross below the 100 cfs "Too Low" threshold within a few days if no rain arrives, though the Pruitt low-stage readings should be treated with lower confidence per local knowledge.
St. Joe recession rate shows mild irregular behavior — fluctuating 0.37-0.43%/hr over the last 3 days rather than monotonically decelerating. This may reflect the complexity of baseflow contributions from 14 HUC12s with different aquifer characteristics draining at slightly different rates.