1. PRECIPITATION SUMMARY:
Negligible precipitation across the entire watershed. All gauge zones received <0.05" for the day. The highest HUC12 total was Boxley at 0.047" — well below any detection threshold. Seven-day antecedent precip has dropped substantially as the Event 4 rainfall (Apr 3-4) rolls out of the 7-day window. Most HUC12s now show 0.04-0.27" 7-day totals, with the exception of the Harriet direct zone (Water Creek 1.099", Tomahawk 0.780") where Event 5 rainfall from Apr 10 remains in the window. The watershed is drying out rapidly.
2. GAUGE RESPONSES:
All gauges continued uninterrupted recession. No significant rises detected.
| Gauge | Start of Day | End of Day | Change | Daily Decline Rate |
|---|---|---|---|---|
| Boxley | 2.39 ft | 2.34 ft | -0.05 ft | ~2.1% |
| Ponca | 145 cfs | 136 cfs | -9 cfs | ~6.2% |
| Pruitt | 4.12 ft / 211 cfs | 3.99 ft / 174 cfs | -0.13 ft / -37 cfs | ~17.5% (cfs) |
| St. Joe | 4.23 ft / 433 cfs | 4.17 ft / 409 cfs | -0.06 ft / -24 cfs | ~5.5% |
| Harriet | 4.31 ft / 608 cfs → 594 cfs (midnight) | 4.21 ft / 529 cfs | -0.10 ft / -65 cfs | ~11.0% (using 594 start) |
| Richland | 1.48 ft | 1.42 ft | -0.06 ft | ~4.1% |
| Bear Creek | 2.29 ft / 5.0 cfs | 2.26 ft / 3.8 cfs | -0.03 ft / -1.2 cfs | ~24% |
Key threshold crossings: - Pruitt exited Optimal (>200 cfs) during the day. It crossed below 200 cfs at approximately 04:30-05:30 CST on Apr 12 and continued declining. At EOD, Pruitt is at 174 cfs — firmly in "Low but Floatable" (100-200 cfs). This finalizes Pruitt's Event 4 Optimal duration: the brief Event 5 re-entry on Apr 11 evening (~17:30-~04:30 Apr 12) lasted approximately 11 hours before falling below 200 again. - Ponca dropped below the "Too Low" threshold (<150 cfs) during the day, reaching 136 cfs by EOD. Ponca is now in "Too Low" territory for recreational purposes. - St. Joe remains in Optimal (409 cfs, well above 200 cfs threshold). - Harriet remains in Optimal (529 cfs, well above 200 cfs threshold).
3. RAINFALL-RESPONSE PAIRS:
No new rainfall-response pairs. This is a clean recession day.
Notable observation on St. Joe: There's a small rise visible in the first few hours (4.20 → 4.24 ft, 421→437 cfs, peaking around 00:45 CST), followed by resumed recession. This is the expected arrival of the Event 5 Pruitt pulse propagating downstream. The rise is tiny (~0.04 ft / ~16 cfs) and occurred approximately 3-4 hours after the Pruitt Event 5 peak (21:00 CST Apr 11). This is consistent with the Pruitt→St. Joe propagation time observed in previous events (~10-22 hours for peak-to-peak at higher flows), though at these low flows the signal is barely detectable.
St. Joe recession rate analysis (Event 4, Day 9-10): - Day 9 (Apr 11): 504→433 cfs = ~14.1%/day decline - Day 10 (Apr 12): 433→409 cfs = ~5.5%/day decline
The dramatic deceleration from ~14% to ~5.5% is notable. However, the Day 10 value may be artificially low due to the small Event 5 propagation bump arriving in early hours. If I use the afternoon values only (where recession is cleaner), St. Joe was ~417 cfs at noon declining to ~409 cfs at midnight = ~1.9%/half-day → ~3.8%/day equivalent. This suggests St. Joe recession is slowing dramatically as it approaches what may be a sustained baseflow level. At this rate, St. Joe would remain above 200 cfs for considerably longer than previously projected — possibly through late April.
Harriet recession rate (Event 4 continued, post-Event 5): - Post-Event 5 clean recession resumed: 594→529 cfs over 24 hours = ~10.9%/day. This is more in line with the previous trajectory than yesterday's noisy data.
4. DOWNSTREAM PROPAGATION:
The small St. Joe bump at 00:00-01:00 CST Apr 12 likely represents the tail end of Event 5 Pruitt pulse propagation. Too small to accurately time, but consistent with expected behavior.
5. MULTI-DAY EVENTS:
Event 4 recession is now in Day 10. Event 5 effects have fully dissipated at all gauges.
Event 4 finalized recreational durations (updated): - Ponca floatable (>150 cfs): Exited on Apr 12 between 15:00-19:00 CST (when it dropped to 136-138 cfs and stayed there). Total floatable duration from Event 4: ~11:00 Apr 4 to ~17:00 Apr 12 = ~8 days (includes the Event 5 bump on Apr 11). - Pruitt Optimal (>200 cfs): Final exit confirmed ~04:30 Apr 12. Last Optimal period was the Event 5 re-entry from ~17:30 Apr 11 to ~04:30 Apr 12 (~11 hours). Total Optimal time from Event 4 onset: initial period ~20:30 Apr 4 to ~11:45 Apr 10 (~135 hr) + Event 5 re-entry ~11 hr = ~146 hours total. - St. Joe Optimal (>200 cfs): Still active at 409 cfs. At ~5.5%/day decline rate (decelerating), projected to remain above 200 cfs through approximately Apr 24-28. Revising upward from previous estimate of Apr 17-18. - Harriet Optimal (>200 cfs): Still active at 529 cfs. At ~11%/day decline rate, projected to remain above 200 cfs through approximately Apr 20-24.
6. ANOMALIES OR SURPRISES:
The St. Joe recession rate deceleration is more pronounced than expected. Going from ~14.5%/day on Days 7-8 to ~5.5% on Day 10 suggests either: (a) significant baseflow contribution from the 1,342 km² of contributing sub-watersheds is sustaining flows, or (b) delayed groundwater/karst return flow is supplementing surface recession. This is consistent with the general pattern that larger watersheds have slower, more sustained recessions, but the degree of deceleration is noteworthy. At this rate, St. Joe's Optimal duration from Event 4 could exceed 20 days — substantially longer than initial projections.
Comparison with local knowledge: The extended Optimal duration at St. Joe and Harriet (projected 20+ days from a single ~1.5" watershed-wide event on wet antecedent conditions) underscores how the large contributing areas of these gauges sustain recreational flows far longer than the upper watershed gauges. This has no direct local knowledge calibration target, but it's an important finding for recreational use planning.