Little Snake River

Evolution of the network

Gage flow trend & changepoints

Of the 6 gages with enough record, 1 is trending down and 0 up, and 2 carry a detected shift. The clearest is YAMPA RIVER AT DEERLODGE PARK, CO, -28.0 points of its long-term median per decade over 42 years (p=0.0018). The other 4 show no clear signal either way.

4 other gage(s) show no significant trend or changepoint (not shown).

How the measurement network itself changed

This basin was not always measured the way it is today — the API-era record is dense and recent, the early record sparse. 3 gage(s) and 18 structure(s) report in 2026, but structure reporting only reached half its modern level around ~1974. Every historical claim below is checked against this: long-term shifts that co-move with the growth of the network carry an explicit measurement-evolution caution, and abandonment screens whose idleness begins before the modern reporting era are flagged †.

Mass-balance (network closure) trend

Structure divrec-history backfill coverage as of the last check: 15% of 142 schematic-relevant structures. 0 year(s) clear the 30% coverage gate so far -- the trend activates automatically once qualifying years span a full decade. No action needed; the nightly backfill keeps extending the record.

Reach gain/loss shifts (1988–2003)

Mass-balance kinks computed for every summer month back to 1988 (40 reach-snapshots) — which reaches gain or lose water, and how that has shifted across decades. Each shift is cross-checked against the observation record above: as more diversions became metered, "unaccounted" water shrinks mechanically, which can masquerade as a hydrologic shift.

No reach shows a statistically significant long-term gain/loss shift.

Groundwater now has its own tab: 1 monitored well(s), water-table trends, stream corridors, and the advisory depletion screen.

Cross-gage pattern fingerprint

Over the 26-year window with full coverage (2001–2026), the dominant shared pattern across 3 gage(s) explains 74% of year-to-year variance (almost certainly a basin-wide climate/snowpack driver).

All gages in this window move with the shared pattern -- no localized outlier.

6 water-level measurements across 1 monitored well(s) — 0 alluvial, 0 bedrock — plus 2 administered well(s) reporting metered pumping.

Well map

3D aquifer x-ray

Every aquifer unit as its own head surface, animated through time.

Water-table trends

Of 0 well(s) with enough record for a trend test: 0 declining, 0 rising.

Wells labeled by administrative world before anything else is said about them: tributary alluvium participates in the priority system; designated-basin and Denver Basin bedrock aquifers are governed differently and are excluded from stream-connection reasoning. Read bedrock declines differently too: deep bedrock aquifers recharge negligibly on human timescales, so a falling bedrock level is storage mining — effectively permanent — not a drought response that a wet year undoes. All screens advisory.

If a call were placed at a given seniority, which structures in this basin would be out of priority, and how much of their decreed rate would be curtailed? Computed from this basin's cached decrees.

Pick a calling right

Real decrees from this basin, ordered by administration number — that is, by actual seniority. The years will look out of order, and that is correct: an administration number encodes the adjudication date as well as the appropriation date, so a right appropriated in 1970 can be administered ahead of one from 1950. A senior call curtails almost everything; a junior one curtails almost nothing.