Day 17 (2026-03-17) — Second consecutive dry day, extended recession continues
Zero precipitation across all 37 HUC12s. This is the second consecutive day with no rainfall (Days 16-17). The 7-day antecedent precip is declining slowly as the March 11 Event 3 rainfall rolls out of the window. Current 7-day values range from 0.43" (Water Creek) to 1.28" (Beech Creek), with most zones in the 0.5-1.0" range. The watershed is transitioning from "moderate" to "dry" antecedent conditions.
All gauges are in sustained recession with no rainfall input. This is a clean, uninterrupted recession — the longest we've observed in the study (now ~6 days post-Event 3 peak for upper gauges).
End-of-day values and 24-hour changes:
| Gauge | Start of Day | End of Day | 24hr Change | Rate |
|---|---|---|---|---|
| Boxley | 2.40 ft | 2.33 ft | -0.07 ft | Steady decline |
| Ponca | 171 cfs | 155 cfs | -16 cfs (-9.4%) | Continuing decline |
| Pruitt | 272 cfs / 4.39 ft | 224 cfs / 4.22 ft | -48 cfs (-17.6%) / -0.17 ft | Accelerating decline |
| St. Joe | 594 cfs / 4.63 ft | 512 cfs / 4.45 ft | -82 cfs (-13.8%) / -0.18 ft | Decline accelerating from plateau |
| Harriet | 656 cfs / 4.40 ft | 649 cfs / 4.39 ft | -7 cfs (-1.1%) / -0.01 ft | Near plateau, very slow |
| Richland | 1.38 ft | 1.29 ft | -0.09 ft | Continuing decline |
| Bear Creek | 2.45 ft / 13.7 cfs | 2.44 ft / 13.2 cfs | -0.01 ft / -0.5 cfs | Near baseflow floor |
Notable observations:
Ponca has reached 155 cfs at end of day — now at the boundary of "Low but Floatable" (150-200 cfs) and very close to "Too Low" (<150 cfs). This gauge has declined from 171→155 cfs today. At this rate (~0.7 cfs/hr), Ponca will cross below 150 cfs (Too Low) within approximately 7 hours, i.e., early morning of Day 18.
Pruitt declined from 272→224 cfs, a 17.6% drop. Still Optimal (>200 cfs) but approaching the lower boundary. At the current recession rate (~2 cfs/hr), Pruitt should exit Optimal in approximately 12 hours (midday Day 18).
St. Joe broke decisively below the apparent 580-590 cfs plateau identified on Day 16. It declined from 594→512 cfs today, a clear acceleration after the plateau. This is significant — the Day 16 hypothesis that St. Joe was approaching a baseflow floor at ~580 cfs was premature. The plateau was likely a slow-draining interflow component that has now exhausted, allowing the recession to resume. St. Joe's decline rate today (~3.4 cfs/hr) is comparable to its Phase 2 rate.
Harriet shows a very different pattern — nearly flat at 649-656 cfs all day, with only slight decline in the final hours. This contrasts sharply with St. Joe's accelerating decline. The divergence between St. Joe (falling) and Harriet (nearly flat) on Day 17 suggests Harriet is receiving sustained baseflow from its local zone (430 km²) and Bear Creek zone (239 km²) that is buffering the declining mainstem input.
Richland Creek fell to 1.29 ft — the lowest level observed in the study. This is approaching true dry-season baseflow for this karst-influenced tributary.
Bear Creek at 13.2 cfs / 2.44 ft — also the lowest observed. Appears to be at or very near its baseflow floor.
None — no rainfall today.
No event propagation to track. However, the recession behavior reveals an interesting pattern: the upper gauges (Ponca, Pruitt) are declining faster than the lower gauges (Harriet), consistent with the smaller-watershed/faster-drainage hypothesis. St. Joe's break below its plateau today creates a useful data point — the "plateau" lasted approximately 2 days (Days 15-16) at ~580-590 cfs before the recession resumed.
This is now Day 6 of the post-Event 3 recession (Event 3 peaked at Ponca on 3/11). The extended dry period is extremely valuable for characterizing recession behavior and baseflow floors.
Recession trajectory summary (Days 14-17, Event 3 post-peak):
| Gauge | Day 14 | Day 15 | Day 16 | Day 17 | Total Decline (Days 14-17) |
|---|---|---|---|---|---|
| Ponca | ~197 cfs | ~186 cfs | ~171 cfs | ~155 cfs | -42 cfs (-21%) |
| Pruitt | ~308 cfs | ~278 cfs | ~272 cfs | ~224 cfs | -84 cfs (-27%) |
| St. Joe | ~732 cfs | ~613 cfs | ~589 cfs | ~512 cfs | -220 cfs (-30%) |
| Harriet | ~878 cfs | ~763 cfs | ~670 cfs | ~649 cfs | -229 cfs (-26%) |
St. Joe plateau breaking: The most significant finding today is that St. Joe's apparent baseflow plateau at ~580-590 cfs (reported Day 16) was not a true baseflow floor — it was a temporary interflow pause. The gauge declined sharply through 570→550→530→512 cfs through the day. This revises the baseflow floor estimate downward significantly. The true baseflow floor for St. Joe is unknown but likely lower than 500 cfs based on the current trajectory. This is an important correction to the hypothesis.
Harriet's resilience: While St. Joe fell ~82 cfs, Harriet fell only ~7 cfs. On Day 16, Harriet was at 670 cfs while St. Joe was at 589 cfs. Today, Harriet is at 649 cfs while St. Joe is at 512 cfs. The Harriet/St. Joe ratio has gone from 1.14 to 1.27 in just one day. This strongly suggests Harriet has substantial local baseflow contributions (springs, deep groundwater) from its 430 km² zone and the Bear Creek zone that are independent of mainstem propagation. This is relevant for recreational planning — the lower river holds its water much longer than the upper reaches.
Local knowledge comparison: The upper river's faster drainage is consistent with the local knowledge about the "pool and drop" nature of the river above Boxley. If the upper watershed has less deep storage and more rapid drainage, this would explain why Ponca and Pruitt dry out proportionally faster than St. Joe and Harriet.