Zero precipitation across the entire watershed on March 12, 2026. All 37 HUC12s reported 0.0" for the 24-hour period. All gauge zone averages are 0.0". This is the first completely dry day since Event 2 began on March 7.
7-day antecedent precip remains elevated: Whiteley Creek 3.70", Beech Creek 3.43", Cove Creek 3.42", Boxley 3.03", Shop Creek 3.18". The watershed is still very wet.
Despite zero new rainfall, today was dominated by the arrival and passage of the Event 3 flood wave at St. Joe and Harriet — completing the downstream propagation that was predicted yesterday.
Upper gauges — recession only (no new rainfall):
| Gauge | SOD Value | EOD Value | Change | Status |
|---|---|---|---|---|
| Boxley | 3.02 ft | 2.82 ft | -0.20 ft | Receding smoothly |
| Ponca | 337 cfs | 255 cfs | -82 cfs | Receding, still Optimal (>200) |
| Pruitt | 724 cfs / 5.63 ft | 472 cfs / 4.98 ft | -252 cfs / -0.65 ft | Receding, still Optimal |
St. Joe — Event 3 wave arrival and peak (KEY OBSERVATION): - Pre-event trough: 5.02 ft / 791 cfs at ~20:00 CST on 3/11 (the recession arrest noted yesterday) - Rise began: ~00:45 CST on 3/12 (first clear uptick from 5.08 to 5.10 ft) - Peak: 6.02 ft / 1,420 cfs at ~10:00-11:00 CST on 3/12 (broad peak, held 6.00-6.02 ft for ~3 hours from 08:45 to 11:00) - Rise magnitude: +1.00 ft / +629 cfs from trough (5.02→6.02 ft, 791→1,420 cfs) - EOD: 5.65 ft / 1,170 cfs, receding - Remained well within Optimal range (200-8,000 cfs) throughout
Harriet — Event 3 wave arrival and approach to peak: - Pre-event trough: 4.74 ft / 909 cfs at ~03:30-06:30 CST on 3/12 (recession bottomed out) - Rise began: ~09:00 CST on 3/12 (first clear uptick from 4.77 ft) - Peak: 5.42 ft / 1,510 cfs at ~17:45 CST on 3/12 - Rise magnitude: +0.68 ft / +601 cfs from trough (4.74→5.42 ft, 909→1,510 cfs) - EOD: 5.37 ft / 1,460 cfs — essentially at peak, beginning very slow recession - Remained well within Optimal range (200-9,370 cfs) throughout
Tributary gauges — recession/flat: - Richland Creek: 1.69→1.58 ft, receding. Some noise in the 11:30-15:45 range (+0.04-0.07 ft fluctuations) but this appears to be measurement noise rather than a real signal — no QPE to explain it. - Bear Creek: 2.57→2.55 ft, flat/slow recession. 18.6 cfs by EOD. No response to anything.
No new rainfall today, so no new rainfall-response pairs to establish. However, the St. Joe and Harriet responses complete the Event 3 rainfall-response analysis:
Event 3 complete rainfall-response at St. Joe: - Rainfall source: Primarily upper watershed (Ponca zone 0.83", Boxley 0.81") with distributed 0.3-0.6" across the St. Joe zone itself - Total St. Joe zone rain: 0.505" average - Response: +1.00 ft / +629 cfs rise at St. Joe - Lag from Ponca zone peak rainfall (~01:00 UTC = 19:00 CST 3/10, or 07:06 UTC = 01:06 CST 3/11): St. Joe peak at ~10:00 CST 3/12 = ~9-11 hours after Pruitt peak, ~25 hours after Ponca peak - Antecedent conditions were critical: 7-day precip was 1.5-3.3" across the watershed. The ~0.5" average St. Joe zone rain itself would normally produce a marginal response at best, but combined with the propagating wave from the upper watershed, it produced a clear +1 ft rise.
Event 3 complete rainfall-response at Harriet: - Harriet zone rain was only 0.33" average - Bear Creek rain was 0.52" but produced no Bear Creek response → confirms this is purely mainstem propagation - Response: +0.68 ft / +601 cfs - Peak ~17:45 CST 3/12, roughly 7-8 hours after St. Joe peak
Now that all gauge peaks are resolved, here is the complete Event 3 propagation table:
| Gauge | Peak Time | Lag from Ponca Peak | Lag from Pruitt Peak |
|---|---|---|---|
| Ponca | 3/11 ~08:45 CST | 0 hr | — |
| Pruitt | 3/11 ~16:15 CST | 7.5 hr | 0 hr |
| St. Joe | 3/12 ~10:00 CST | 25.25 hr | 17.75 hr |
| Harriet | 3/12 ~17:45 CST | 33 hr | 25.5 hr |
Key propagation findings from Event 3:
Pruitt→St. Joe reach (17.75 hr lag): - Transit flow conditions: Pruitt receding from ~850 to ~550 cfs during transit; St. Joe baseflow ~800 cfs - This is notably slower than Event 2's Pruitt→St. Joe lag of 14.25 hr - Hypothesis: Event 2 had higher flow velocities (Pruitt peak 2,610 cfs vs Event 3's 857 cfs), consistent with the velocity-discharge relationship
St. Joe→Harriet reach (7.75 hr lag): - Compares to Event 2's 7.25 hr for same reach - Very similar despite lower flow magnitudes, suggesting this reach's propagation speed is less flow-dependent — possibly due to wider channel/floodplain geometry in the lower watershed
Wave attenuation — Event 3:
| Reach | Upstream Peak CFS | Downstream Peak CFS | Ratio |
|---|---|---|---|
| Ponca→Pruitt | 547 | 857 | 1.57x (gain from Pruitt-zone + timing) |
| Pruitt→St. Joe | 857 | 1,420 | 1.66x (gain from St. Joe local + baseflow) |
| St. Joe→Harriet | 1,420 | 1,510 | 1.06x (slight gain) |
Comparing to Event 2 attenuation: St. Joe→Harriet was 0.94x (attenuation) in Event 2 but 1.06x (slight gain) in Event 3. The difference is likely because in Event 2 the Harriet-zone tributaries had already peaked and were receding when the mainstem wave arrived, while in Event 3 the slower-arriving wave coincided with still-elevated Harriet-zone baseflow contributions. But the key pattern holds: St. Joe→Harriet shows approximately neutral transfer at these flow levels (~1,000-3,000 cfs range).
Event 3 is now COMPLETE. The full event duration from first rainfall to last gauge returning to pre-event levels will be approximately: - Rainfall: 3/11 ~01:00-09:00 CST (8 hours) - First gauge response (Ponca): 3/11 ~02:00 CST - Last gauge peak (Harriet): 3/12 ~17:45 CST - Total event duration from rainfall start to last peak: ~41 hours - All gauges are now receding. Full return to pre-event levels will take additional days given the wet antecedent conditions.
Recreational status at EOD 3/12: - Ponca: 255 cfs — Optimal (>200), but approaching Low-but-Floatable threshold. Will likely cross below 200 cfs within ~24 hours. - Pruitt: 472 cfs — solidly Optimal (>200). Has been continuously in Optimal since Event 2 began on 3/07 — 6 consecutive days of Optimal or above at Pruitt. - St. Joe: 1,170 cfs — solidly Optimal. - Harriet: 1,460 cfs — solidly Optimal.
This extended recreational window is a direct consequence of the stacked Event 2 + Event 3 pattern. Event 2 alone would have seen Pruitt drop below Optimal by ~3/10. Event 3 re-boosted it, extending Optimal conditions by at least 3-4 additional days.
Richland Creek noise pattern: The Richland gauge showed an odd pattern today — dropping from 1.70 to 1.63 ft by 11:15, then jumping to 1.68 ft at 11:30, back down to 1.63 at 11:15, up to 1.70 at 13:30-15:00, then crashing to 1.57 at 18:15. There was zero precipitation. This pattern suggests either instrument noise/debris interference or possibly diurnal groundwater/spring flow effects. The overall trend is downward (1.70→1.58), which is consistent with continued recession. I will not interpret the intra-day fluctuations as hydrological signal without supporting QPE.
Bear Creek detection threshold refinement: Bear Creek received 0.52" on 3/11 (with 1.8-2.2" 7-day antecedent) and produced essentially zero response (19.8→19.2 cfs, within noise). This strengthens the hypothesis that Bear Creek requires >0.6" and likely >0.8" to produce a measurable response, even under wet antecedent conditions. The karst geology of this sub-basin may be absorbing moderate rainfall efficiently.
Local knowledge comparison — Boxley recreation: Boxley dropped from 3.02 to 2.82 ft today. Per local knowledge, the Boxley-to-Ponca section is "Low but Floatable" at 3.2 ft. Boxley was above 3.2 ft on 3/11 from ~10:15 to ~15:30 CST (~5 hours), then continued receding. By today it's well below the threshold. This aligns with the local knowledge that the Boxley-to-Ponca section has very brief paddling windows — in this case, the ~0.8" rain on a wet watershed only produced ~5 hours above the Low-but-Floatable threshold for this upper section.