Hydrohistorian
Little Snake River on the ground — the ditches, wells, reservoirs and gages of Water District 55 · clicktap anything for its record
Runoff outlook — Little Snake R nr Lily: even odds of at least 11 kAF over 06-01 to 07-31 — 12% of a normal season, per NRCS, issued 2026-06-01 — the season’s final; new forecasts begin in January. Full snow & runoff picture — charts, forecast history and how the forecasts have verified →
Sites, exceedance bands and sources
Little Snake R nr Lily — 06-01 to 07-31 volume, thousand acre-feet (chance the volume is AT LEAST this):
| 90% | 70% | 50% | 30% | 10% | Normal |
|---|---|---|---|---|---|
| 5 | 8 | 11 | 28 | 51 | 92 |
Snow-water equivalent and medians (1991–2020) from NRCS SNOTEL; seasonal volume forecasts from the NRCS National Water and Climate Center. Sites and forecast points are assigned to the district whose boundary contains them — snowpack that feeds this district can also sit in a neighboring headwater district. Toggle the Snow chip on the map above to see the sites.
Topology cross-check: 1 parent disagreement, 5 sizable streams not on this network (vs DWR's route framework — under review)
This flow network was built mechanically; DWR's Source Water Route Framework disagrees with it in the places below. Each row is a question a human reviewer has not yet answered — not an error verdict. Checked 6 streams, 5 agree. Know this water? Tell us →
| Stream | This site routes it to | DWR routes it to |
|---|---|---|
| Buffalo Gulch | the mainstem | Yampa River |
Sizable streams DWR maps here that this network does not carry:
Powder Wash (30 mi) · Greasewood Gulch (19 mi) · Thompson Draw (14 mi) · Deep Canyon (5 mi) · Rice Draw (4 mi)
Full diagnostic snapshot pending — this district's weekly-style report (system status, active calls, hydrographs, anomaly flags) is produced by the nightly rotation and appears here after its first run. The tabs above are live now.
Schematic
Historical
Evolution of the network
Trends
This year, in context
In the weeks around 2026-07-06 (the newest reading on file), flows at the 3 ranked gages are running at a median 20% of their own long-term norm for this window — 3 below a typical year, 0 at or above. Driest relative to its record: LITTLE SNAKE RIVER NEAR LILY, CO, ranking 3rd lowest of 105 years.
How this comparison is made
Each gage's mean flow over the 3 days either side of 2026-07-06, compared with the same window in every year of its own record — so a gage is only ever measured against itself, and gages with no record in the window are counted out rather than guessed.
Gage flow trend & changepoints
What counts as a trend here
Computed 2026-08-30 21:06 from 6 gage(s) with cached period-of-record data. The series is each gage's annual mean flow in cfs (years with ≥300 days of record). Mann-Kendall (trend, with the Hamed–Rao correction for serial correlation — persistence can otherwise fake significance) and Pettitt (changepoint) both require at least 8 years spanning at least 10 years of record. A gage below that reports no signal — which is not the same as “no change.” The %-per-decade figure is the same Sen slope divided by the gage's median annual flow, for comparing across streams of very different size; it is omitted for near-ephemeral channels where the median is too small to divide by honestly.
None of the 6 gages with enough record shows a significant trend or a detected shift — which is itself the finding.
What drought has cost here
Since 1991, federal crop insurance has paid $487,504 in drought-caused claims across Moffat, Routt counties — 1.4% of all insured crop losses there. The worst year was 2013 ($227,009).
USDA crop-insurance indemnities where the recorded cause of loss is drought, summed over the counties this district's gages sit in. Counties overlap water districts imperfectly, and insured-crop claims are a floor on drought damage, not a total. Source: USDA RMA cause-of-loss files.
No gage shows a statistically significant trend or changepoint yet.
6 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 †.
| Decade | Gages with data (median yr) | Structures reporting (median yr) |
|---|---|---|
| 1920s | 1 | 0 |
| 1930s | 1 | 0 |
| 1940s | 2 | 0 |
| 1950s | 2 | 0 |
| 1960s | 2 | 0 |
| 1970s | 2 | 11 |
| 1980s | 3 | 13 |
| 1990s | 4 | 17 |
| 2000s | 3 | 18 |
| 2010s | 3 | 18 |
| 2020s | 3 | 16 |
Mass-balance (network closure) trend
Structure divrec-history backfill coverage as of the last check: 6% of 337 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
Not enough gages with a long enough common-coverage window yet to fingerprint shared patterns.
Data provenance & quality
Where these numbers come from and how far they can be trusted. Grade C (3/6 points) — the components below are the finding; the letter alone is not. Sources: DWR HydroBase snapshot HydroBase_CO_20260707 (imported 2026-08-19) for history, plus the CDSS REST API for current conditions.
| Check | State | What was measured |
|---|---|---|
| gage freshness | stale | newest gage reading is 55 day(s) old (target 7) |
| diversion record | expected-lag | newest diversion record is 320 day(s) old (DWR publishes ~1 year in arrears) |
| structure coverage | sparse | 6% of schematic structures have data |
Independent check: PASS — 100.0000% agreement across 90,869 stored values re-checked against DWR's authoritative record (HydroBase_CO_20260707), over 20 structures. 0 disagreement(s) beyond a 0.01 cfs tolerance. Checked 2026-08-19; a rotating sample covers the whole basin across successive runs, and the structures this report cites are checked every time.
Federal cross-check: PASS — 98.13% day-level agreement with USGS's own published records for the same gages, across 6 co-listed station(s) and 87,954 overlapping days (within max(2%, 0.5 cfs) daily). Pre-1950 records at some gages carry known between-agency day-stamp and transcription differences — scored at each year's best ±1-day alignment; residual disagreement is real historical divergence, flagged for review.
6 gage(s) / 87,145 daily values (1921-10-01–2026-07-06); 33 structure(s) with diversion records; 477 with decreed rights. Methodology has not yet had independent expert review — treat every figure as an advisory screen, not an administrative or legal conclusion.
Groundwater
6 water-level measurements across 1 monitored well(s) — 0 alluvial, 0 bedrock — plus 2 administered well(s) reporting metered pumping.
What is being counted
Observation wells and pumping wells are different populations and are never conflated: water levels come from monitored observation wells, and metered pumping comes from administered wells reporting through diversion records. Click any well to chart its own record.
Well map
3D aquifer x-ray
Every aquifer unit as its own head surface, animated through time.
How the surfaces are built, and what they are not
Alluvial water table on top, Denver Basin members (Dawson, Denver, Arapahoe, Laramie–Fox Hills) stacked beneath where measured, interpolated from measured water levels. Units are never mixed; a surface exists only inside its own unit's well coverage, with no extrapolation; thin epochs are suppressed and say why. Vertical scale is exaggerated for readability and z is head elevation in feet. These are measured heads, not a calibrated groundwater model.
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.
Snow and runoff
Snow-water equivalent, WY2026
| SNOTEL site | Elev (ft) | SWE (in) | Median (in) | % of median | Typical peak |
|---|
NRCS SNOTEL, daily. Sites are assigned to the district whose boundary contains them — the snow that feeds this district can also sit in a neighboring headwater district.
Runoff outlook — Little Snake R nr Lily
NRCS's final issue (2026-06-01) calls it even odds that at least 11 kAF arrives over 06-01 to 07-31 — 12% of a normal season; almost certainly at least 5, probably not more than 51. Our own record at this gage shows 10 kAF actually delivered (partial record: 36 of 61 days). New forecasts begin in January. How to read these numbers →
| 90% chance of at least | 70% chance of at least | 50% chance of at least | 30% chance of at least | 10% chance of at least | Normal | Observed |
|---|---|---|---|---|---|---|
| 5 | 8 | 11 | 28 | 51 | 92 | 10 |
How good are these forecasts here? (1950–2025)
Grading every April issue against what the river then delivered, measured at this gage’s own record — 75 seasons: the median miss of the 50% forecast is 25%, with a high bias of 8%, and the observed volume landed inside the stated 10–90% band 78% of the time (a calibrated forecast would say 80%).
Computed by this site: NRCS's archived April issues (their period as issued each year) against the observed volume in DWR’s published record; years with under 90% daily coverage are dropped, not summed. A grade of the forecast, never of the forecasters — these are hard rivers. How this point ranks among every graded Colorado forecast point →
Legal
Decreed rights on this network run from 1890-05-01 to 2023-03-30. Of the 20 structures with a yield estimate, the median one’s senior right was in priority 10% of a median irrigation season and 0% in a dry one. 4 abandonment screens and 10 compliance flags are listed below as leads for review — a screen is not an abandonment and a flag is not a violation.
Rights on file: 522 across 477 structure(s); 17 structure(s) carry 0 court-case references. Advisory reading aids on public DWR data — not administrative or legal conclusions.
Is the river getting harder to divert from?
Over 2003–2025, administration on this district has been tightening: 1 of 3 measures (days under call, calls set, seniority of the controlling call) are moving toward more administration, none the other way.
The three measures, year by year
One row per whole calendar year inside the call record's coverage (23 years); partly-covered years are omitted rather than reported as quiet. Trend is Mann-Kendall with the same significance gate as every other trend on this site. Counted from DWR's published call record, which begins in the early 2000s: earlier years are absent, not quiet. A rise in the number of calls set can also reflect how finely an administrator records one episode, which is why days under call -- insensitive to that -- is the component to read first. Advisory summary of the public record, not an administrative finding.
| Year | Days under call | Calls set | Controlling priority (median) |
|---|---|---|---|
| 2014 | 204 | 38 | 1882-04-01 |
| 2015 | 215 | 27 | 1882-04-01 |
| 2016 | 198 | 56 | 1882-04-01 |
| 2017 | 185 | 73 | 1883-06-30 |
| 2018 | 197 | 95 | 1882-04-01 |
| 2019 | 177 | 30 | 1882-04-01 |
| 2020 | 204 | 109 | 1882-04-01 |
| 2021 | 250 | 158 | 1882-04-01 |
| 2022 | 249 | 87 | 1882-04-01 |
| 2023 | 365 | 50 | 1904-01-02 |
| 2024 | 306 | 75 | 1882-04-01 |
| 2025 | 186 | 97 | 1882-04-01 |
Why diversions stopped — call-based explanations
Sustained diversion stops matched to senior administrative calls.
- ESCALANTA PUMP 2 (5500504) DWR↗ stopped 2025-08-24 (30+ days) — call at SLATER FORK DITCH [heuristic-strong]
- ESCALANTA PUMP 2 (5500504) DWR↗ stopped 2025-07-24 (5+ days) — call at SQUARE S CONS D ALT PT [heuristic-strong]
- ESCALANTA PUMP 1 (5500503) DWR↗ stopped 2025-07-19 (37+ days) — call at METZ & REIGAN DITCH [heuristic-strong]
- MAJORS PUMP NO 1 (5500505) DWR↗ stopped 2025-07-14 (5+ days) — call at METZ & REIGAN DITCH [heuristic-strong]
- GORDON C. WINN PUMP 1 (5500514) DWR↗ stopped 2025-07-10 (20+ days) — call at METZ & REIGAN DITCH curtailing 100% of its decreed rate [heuristic-strong]
- ONECO PUMP NO 2 (5500509) DWR↗ stopped 2025-07-08 (21+ days) — call at METZ & REIGAN DITCH curtailing 100% of its decreed rate [heuristic-strong]
- ESCALANTA PUMP 2 (5500504) DWR↗ stopped 2025-06-17 (13+ days) — call at WILLOW CK DITCH [heuristic-strong]
- ESCALANTA PUMP 1 (5500503) DWR↗ stopped 2025-06-16 (15+ days) — call at WILLOW CK DITCH [heuristic-strong]
- MAJORS PUMP NO 1 (5500505) DWR↗ stopped 2025-06-16 (18+ days) — call at WILLOW CK DITCH [heuristic-strong]
- ONECO PUMP NO 2 (5500509) DWR↗ stopped 2025-06-11 (15+ days) — call at METZ & REIGAN DITCH curtailing 100% of its decreed rate [heuristic-strong]
- LEFEVRE NO 1 PUMP (5500537) DWR↗ stopped 2025-06-11 (15+ days) — call at METZ & REIGAN DITCH curtailing 100% of its decreed rate [heuristic-strong]
- MAJORS PUMP NO 2 (5500506) DWR↗ stopped 2025-05-22 (12+ days) — call at METZ & REIGAN DITCH curtailing 100% of its decreed rate [heuristic-strong]
Right yield — how often could these rights actually divert?
Share of irrigation-season days each structure's rights were not called out, derived from the 22-year district-scoped call record (senior right = floor, junior right = ceiling constraint). Call-record-derived; DWR's own analysis governs where available.
| Structure | Senior priority | Senior right: median / dry yr | Junior right: median / dry yr |
|---|---|---|---|
| MAJORS PUMP NO 2 (5500506) DWR↗ | 1890-05-01 | 16.4% / 4.7% | 7.5% / 0.0% |
| ONECO PUMP NO 2 (5500509) DWR↗ | 1890-05-01 | 16.4% / 4.7% | 7.5% / 0.0% |
| RINKER PUMP D (5500519) DWR↗ | 1916-06-26 | 7.5% / 0.0% | 7.5% / 0.0% |
| RAFTOPOULOS LSR PUMP (5501081) DWR↗ | 1924-06-01 | 10.0% / 0.0% | 7.5% / 0.0% |
| LEFEVRE NO 1 PUMP (5500537) DWR↗ | 1975-09-17 | 7.5% / 0.0% | 7.5% / 0.0% |
| DEWEY SHERIDAN D (5501011) DWR↗ | 1947-04-27 | 7.5% / 0.0% | 7.5% / 0.0% |
| NINE MILE IRR DITCH (5500507) DWR↗ | 1950-02-17 | 10.0% / 0.0% | 10.0% / 0.0% |
| GORDON C. WINN PUMP 2 (5500515) DWR↗ | 1963-05-01 | 7.5% / 0.0% | 7.5% / 0.0% |
| HELLS CANYON DITCH (5502035) DWR↗ | 1920-07-01 | 7.5% / 0.0% | 7.5% / 0.0% |
| HAYSTACK PUMP (5502034) DWR↗ | 1936-08-01 | 7.5% / 0.0% | 7.5% / 0.0% |
| NINE MILE IRR PL (5500508) DWR↗ | 1961-08-14 | 7.5% / 0.0% | 7.5% / 0.0% |
| DUNN PUMP & PL (5500538) DWR↗ | 1975-10-01 | 7.5% / 0.0% | 7.5% / 0.0% |
Abandonment radar (4 screens)
Absolute rights with 10+ years of no recorded diversions. Screens only — storage, alternate points, and plan operations can explain nonuse lawfully. And diversion REPORTING itself only reached its modern level ~1974 — idleness that begins before then may be unreported use, not nonuse (flagged † below).
- ARAMBEL WELL 2 (5506003) DWR↗ (1955-06-15, 0.2 cfs decreed): last active 1986 — 37 years idle
- ESCALANTA DITCH (5500516) DWR↗ (1899-10-01, 6.0 cfs decreed): last active 2003 — 20 years idle
- PERUSEK DITCH (5500510) DWR↗ (1928-09-24, 3.8 cfs decreed): last active 2008 — 15 years idle
- HELLS CANYON DITCH (5502035) DWR↗ (1920-07-01, 7.0 cfs decreed): last active 2013 — 10 years idle
Compliance screens (10 advisory flags)
Screened 25 of 477 structures with rights (30 have diversion history on file). A flag is a lead for expert review — augmentation plans, exchanges, and free-river conditions can make over-decree diversions lawful and are deliberately not modeled.
- RAFTOPOULOS LSR PUMP (5501081) DWR↗: Observed p99 daily rate 14.0 cfs (max 14.0) exceeds total decreed absolute 11.8 cfs across 6296 recorded day(s).
- LEFEVRE NO 1 PUMP (5500537) DWR↗: Observed p99 daily rate 11.3 cfs (max 15.0) exceeds total decreed absolute 10.0 cfs across 6839 recorded day(s).
- NINE MILE IRR DITCH (5500507) DWR↗: Observed p99 daily rate 10.0 cfs (max 10.0) exceeds total decreed absolute 8.0 cfs across 5726 recorded day(s).
- PERUSEK DITCH (5500510) DWR↗: Observed p99 daily rate 10.0 cfs (max 18.8) exceeds total decreed absolute 3.8 cfs across 2008 recorded day(s).
- HAYSTACK PUMP (5502034) DWR↗: Observed p99 daily rate 9.3 cfs (max 10.0) exceeds total decreed absolute 6.7 cfs across 1514 recorded day(s).
- NINE MILE IRR PL (5500508) DWR↗: Observed p99 daily rate 8.0 cfs (max 8.0) exceeds total decreed absolute 6.5 cfs across 6536 recorded day(s).
- GORDON C. WINN PUMP 1 (5500514) DWR↗: Observed p99 daily rate 8.0 cfs (max 8.0) exceeds total decreed absolute 2.2 cfs across 6158 recorded day(s).
- ADOLPH EDINGER D & PL (5500502) DWR↗: Observed p99 daily rate 4.1 cfs (max 4.7) exceeds total decreed absolute 4.0 cfs across 384 recorded day(s).
- STUDEBAKER PUMP (5502037) DWR↗: Observed p99 daily rate 3.0 cfs (max 3.0) exceeds total decreed absolute 2.0 cfs across 2324 recorded day(s).
- KAWCAK PUMP EAST (5500558) DWR↗: All rights on this structure are conditional (no absolute decree), but divrec shows 30 day(s) of nonzero diversion -- worth checking whether an absolute right was decreed since the cached net amounts, or the diversions run under another plan.
Seniority (top structures by decreed rate)
| Structure | Senior priority date | Rights | Decreed abs (cfs) | Decreed abs (AF) | Conditional? |
|---|---|---|---|---|---|
| MAJORS PUMP NO 2 (5500506) DWR↗ | 1890-05-01 | 6 | 18.6 | 0 | — |
| ONECO PUMP NO 2 (5500509) DWR↗ | 1890-05-01 | 6 | 15.3 | 0 | — |
| RINKER PUMP D (5500519) DWR↗ | 1916-06-26 | 3 | 12.0 | 0 | — |
| RAFTOPOULOS LSR PUMP (5501081) DWR↗ | 1924-06-01 | 3 | 11.8 | 69 | — |
| LEFEVRE NO 1 PUMP (5500537) DWR↗ | 1975-09-17 | 1 | 10.0 | 0 | — |
| DEWEY SHERIDAN D (5501011) DWR↗ | 1947-04-27 | 1 | 10.0 | 0 | — |
| NINE MILE IRR DITCH (5500507) DWR↗ | 1950-02-17 | 1 | 8.0 | 0 | — |
| GORDON C. WINN PUMP 2 (5500515) DWR↗ | 1963-05-01 | 1 | 7.8 | 0 | — |
| HELLS CANYON DITCH (5502035) DWR↗ | 1920-07-01 | 1 | 7.0 | 0 | — |
| HAYSTACK PUMP (5502034) DWR↗ | 1936-08-01 | 1 | 6.7 | 0 | — |
| NINE MILE IRR PL (5500508) DWR↗ | 1961-08-14 | 2 | 6.5 | 0 | — |
| ESCALANTA DITCH (5500516) DWR↗ | 1899-10-01 | 1 | 6.0 | 0 | — |
| DUNN PUMP & PL (5500538) DWR↗ | 1975-10-01 | 1 | 6.0 | 0 | — |
| VISINTAINER DITCH (5500513) DWR↗ | 1929-09-09 | 2 | 5.0 | 0 | — |
| ONECO DITCH (5501509) DWR↗ | 1901-04-29 | 1 | 4.2 | 0 | — |
No inventory or legal-document changes detected since the daily watch began.
Water-court filings this month (division-wide)
5 applications in the 2026-08 resume for this basin's division — new rights, changes, augmentation plans — from the water clerk's statutory monthly notice (C.R.S. 37-92-302), the earliest public signal of a new claim. Filings are division-wide, not district-filtered: check the county column. Full resume PDF at the Judicial Branch →
Anyone affected may file a statement of opposition until 2026-10-31 (61 days left). C.R.S. 37-92-302(3): due by the last day of the second month following the filing month — computed, not legal advice; confirm with the water clerk.
All 5 filings, with excerpts
| Case | What it asks | County | Excerpt |
|---|---|---|---|
2026CW10
|
— | ROUTT | 2026CW10 Routt County Application for Absolute Water Rights (Storage). Applicant: Wilton Earle 785 Valley View Drive Craig, CO 81625; 970-824-6258; rettae74@gmail.com.; Logan Earle 785 Valley View Drive Craig, CO 81625; 970-620-5288; earlelogan679@gmail.com St… |
2026CW11
|
— | RIO BLANCO | 2026CW11 Rio Blanco County Application for Simple Change in Surface Point of Diversion. Applicants: John and Diana Hartman, 2804 E Main Street, Rangely, CO 81648, 970-618-0088, dgrantelk@gmail.com Structure: Calvat Ditch. Original Decree: CA099. Case: 11/26/19… |
2026CW3009
|
reasonable diligence | — | 2026CW3009 ROUTT AND RIO BLANCO COUNTIES, Prima Ranches LLC, c/o David Harbaugh, 3575 E Cherry Creek North Drive, Denver, CO 80209, (303) 478-8997. Please address all correspondence to: Geoffrey M. Williamson, Katherine Carter, Berg Hill Greenleaf Ruscitti LLP… |
2026CW3010
|
change of water right, plan for augmentation, new underground right | ROUTT | 2026CW3010 ROUTT COUNTY Water Division: 6. DISTRICT COURT, WATER DIVISION SIX, STATE OF COLORADO, Routt County Combined Court, 1955 Shield Drive, Unit 200, Steamboat Springs, CO 80487. CONCERNING THE APPLICATION FOR WATER RIGHTS OF SIDNEY PEAK RANCH OWNERS’ AS… |
2026CW3011
|
change of water right | RIO BLANCO | 2026CW3011 RIO BLANCO COUNTY – WHITE RIVER. Mahogany Ranch, LLC, c/o Kevin L. Patrick, and John M. Sittler, Patrick, Miller & Noto, P.C., 229 Midland Ave., Basalt, CO 81621. (970) 920-1030. APPLICATION FOR CHANGE OF WATER RIGHT. Summary of Application: Applica… |
Call cascade
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.
What this does and doesn't model. Seniority arithmetic only: every right junior to the call is treated as curtailed. It does not model reach applicability — structures downstream of the calling point are not administered by it — and it applies no futile-call judgment. Read it as “who is junior to this date, and by how much,” not as a prediction of what the Division Engineer would actually order.
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.
Or enter an administration number directly
DWR administration numbers encode appropriation and adjudication dates; lower is more senior.