1. PRECIPITATION SUMMARY: Zero precipitation across all 37 HUC12s. This is the 6th consecutive dry day (since the end of Pulse 3 on Apr 4). 7-day antecedent precip remains unchanged from yesterday at 1.4-2.8" across the watershed, but these totals will begin rolling off the 7-day window starting tomorrow (Apr 3 Pulse 1 rain drops out of the window on Apr 10).
2. GAUGE RESPONSES: All gauges continue monotonic recession. No significant rises at any gauge.
| Gauge | Start of Day | End of Day | Daily Decline | Daily % Decline | Status |
|---|---|---|---|---|---|
| Boxley | 2.53 ft | 2.43 ft | -0.10 ft | -3.9% | Approaching pre-event (1.84 ft) slowly |
| Ponca | 171 cfs | 157 cfs | -14 cfs | -8.2% | Low-but-Floatable (150-200). Approaching 150 cfs threshold. |
| Pruitt | 254/4.28 ft | 221/4.16 ft | -33 cfs/-0.12 ft | -13.0% (cfs) | Optimal (>200) but declining toward threshold |
| St. Joe | 753/4.92 ft | 613/4.64 ft | -140 cfs/-0.28 ft | -18.6% (cfs) | Optimal — well above 200 cfs |
| Harriet | 990/4.84 ft | 793/4.59 ft | -197 cfs/-0.25 ft | -19.9% (cfs) | Optimal — well above 200 cfs |
| Richland | 1.81 ft | 1.68 ft | -0.13 ft | -7.2% | Continued slow recession |
| Bear Creek | 14.1 cfs/2.46 ft | 10.6 cfs/2.39 ft | -3.5 cfs/-0.07 ft | -24.8% | Approaching baseline (~4 cfs pre-event) |
Key observations:
Ponca crossed below Optimal on Apr 7 and is now approaching the Low-but-Floatable floor (150 cfs). At 157 cfs at end of day and declining ~8%/day, Ponca will cross below 150 cfs (Too Low) within ~1 day (~Apr 10-11). This matches the Day 39 projection.
Pruitt CFS continued declining while height showed a new pattern. Height dropped from 4.28 ft to ~4.15-4.16 ft through the middle of the day, but then appeared to stabilize/slightly rebound in the evening (4.15→4.16→4.17 ft from ~18:00 onward). CFS also showed slight stabilization in the evening at 219-221 cfs. This is the second consecutive day of late-day height stabilization at Pruitt. This reinforces the Day 39 observation about Pruitt height behavior at intermediate flows — the river-right flow redistribution noted in local knowledge may be creating a plateau effect where the gauge on river left becomes less sensitive to small flow changes in this range. Confidence increases from low-moderate to moderate.
Pruitt is approaching 200 cfs (Optimal floor). At 221 cfs declining ~13%/day, Pruitt should cross below 200 cfs around Apr 10-11. Total Optimal duration for Pruitt from Event 4 will be approximately 108-120 hours (4.5-5 days).
St. Joe recession rate continued decelerating. Day 4 was 21.2%, Day 5 is 18.6%. The deceleration pattern is holding — subsurface/baseflow is sustaining flow. At 613 cfs, St. Joe remains well within Optimal (200-8000) and at the current trajectory (~15%/day by tomorrow), will remain above 200 cfs for approximately 7-8 more days.
Harriet recession also decelerating. Day 4 was 22.1%, Day 5 is 19.9%. At 793 cfs, similar long tail expected.
Bear Creek approaching true baseline. At 10.6 cfs, down from peak of 203 cfs — 94.8% decline from peak. Pre-event baseline was 4.2 cfs. Bear Creek will reach baseline within ~2 more days. This confirms Bear Creek as the flashiest gauge in the network with the fastest return to baseline.
3. RAINFALL-RESPONSE PAIRS: No new pairs — dry day.
4. DOWNSTREAM PROPAGATION: No new propagation to track. Pure baseflow recession across all gauges.
5. MULTI-DAY EVENTS: This is Day 6 of the clean dry recession from Event 4. Updated recession table:
| Gauge | Peak Value | Day 5 End (Apr 9) | % from Peak | Days since peak |
|---|---|---|---|---|
| Boxley | 3.89 ft | 2.43 ft | -37.5% | 5.4 |
| Ponca | 823 cfs | 157 cfs | -80.9% | 5.3 |
| Pruitt | 867 cfs | 221 cfs | -74.5% | 4.9 |
| St. Joe | 2,630 cfs | 613 cfs | -76.7% | 4.4 |
| Harriet | 2,720 cfs | 793 cfs | -70.8% | 4.2 |
| Richland | 3.58 ft | 1.68 ft | -53.1% | 5.0 |
| Bear Creek | 203 cfs | 10.6 cfs | -94.8% | 5.3 |
Updated recession rates by day (% decline in CFS or height per day):
| Gauge | Day 1 | Day 2 | Day 3 | Day 4 | Day 5 | Trend |
|---|---|---|---|---|---|---|
| Boxley (ht) | ~7% | ~5.4% | ~4.5% | ~3.9% | ~3.9% | Stabilizing ~4% |
| Ponca | ~21% | ~13% | ~11.3% | ~8.2% | ~8.2% | Approaching asymptote |
| Pruitt | ~27% | ~19% | ~15.1% | ~13.0% | ~13.0% | Continued deceleration |
| St. Joe | ~40% | ~29% | ~21.2% | ~18.6% | — | Continued deceleration |
| Harriet | ~41% | ~26% | ~22.1% | ~19.9% | — | Continued deceleration |
| Bear Creek | ~50% | ~33% | ~24.2% | ~24.8% | — | Flattening ~25% |
6. ANOMALIES OR SURPRISES:
Pruitt height stabilization now a two-day pattern. On both Apr 8 and Apr 9, Pruitt height declined through the day and then stabilized or slightly rebounded in the late afternoon/evening. On Apr 8 it stabilized at 4.28-4.30 ft; on Apr 9 at 4.15-4.17 ft. This is consistent with a diurnal pattern possibly related to evapotranspiration reduction in the evening (less ET = more water reaching the gauge) or, more likely, the river-right flow redistribution noted in local knowledge where the gauge becomes less sensitive at these intermediate levels. The CFS also shows some evening stabilization, suggesting the rating curve may be mapping this height plateau to a flow plateau. Not a concern for research validity — just a calibration artifact to note when interpreting Pruitt at flows below ~250 cfs.
Ponca recession rate appears to be asymptoting. Both Day 4 and Day 5 showed ~8.2% decline — the deceleration has effectively stopped, and Ponca is now in a near-linear decline phase. At this rate (~13 cfs/day), Ponca will reach 150 cfs around Apr 10 and approach baseline (~88 cfs pre-event) around Apr 17-18.