Hydrohistorian
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.
Evolution of the network
Gage flow trend & changepoints
What counts as a trend here
Computed 2026-08-20 09:07 from 23 gage(s) with cached period-of-record data. Mann-Kendall (trend) 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.”
Of the 23 gages with enough record, 6 are trending down and 0 up, and 4 carry a detected shift. The clearest is EAGLE RIVER AT RED CLIFF, CO., -5.3 points of its long-term median per decade over 97 years (p<0.0001). The other 17 show no clear signal either way.
| Gage | Trend | Change / decade points of median | Significance | Years | Changepoint |
|---|---|---|---|---|---|
|
▸
EAST FORK EAGLE RIVER NEAR CLIMAX, CO EAGCLICO |
↓ decreasing | -39.9 | p=0.042 | 25 | — |
|
▸
EAGLE RIVER BELOW MILK CREEK NEAR WOLCOTT, CO EAGMILCO |
↓ decreasing | -37.5 | p=0.002 | 21 | ~2017 |
|
▸
GORE CREEK AT MOUTH NEAR MINTURN, CO GORCRECO |
↓ decreasing | -14.9 | p=0.006 | 31 | ~2011 |
|
▸
LAKE CREEK NEAR EDWARDS, CO LAKNEDCO |
↓ decreasing | -14.0 | p=0.003 | 33 | ~2011 |
|
▸
EAGLE RIVER AT RED CLIFF, CO. EAGREDCO |
↓ decreasing | -5.3 | p=0.000 | 97 | ~1952 |
|
▸
HOMESTAKE CREEK AT GOLD PARK, CO. HOMGOLCO |
↓ decreasing | -4.9 | p=0.047 | 61 | — |
17 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. 16 gage(s) and 151 structure(s) report in 2026, but structure reporting only reached half its modern level around ~1951. 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) |
|---|---|---|
| 1910s | 1 | 0 |
| 1920s | 1 | 0 |
| 1940s | 3 | 0 |
| 1950s | 4 | 208 |
| 1960s | 8 | 0 |
| 1970s | 10 | 244 |
| 1980s | 10 | 268 |
| 1990s | 12 | 239 |
| 2000s | 16 | 132 |
| 2010s | 14 | 141 |
| 2020s | 15 | 143 |
Mass-balance (network closure) trend
Structure divrec-history backfill coverage as of the last check: 5% of 694 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 (1950–2026)
Mass-balance kinks computed for every summer month back to 1950 (1950 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.
- LAKE CREEK NEAR EDWARDS, CO: reach shifted from -122 cfs to -517 cfs summer mean (more losing, p=0.018, 33 yr) [sedimentary uplands: moderate groundwater connectivity -- gain/loss shifts can be real aquifer response; corroborate with nearby well records]
- EAGLE RIVER BELOW GYPSUM, CO.: reach shifted from +1086 cfs to +94 cfs summer mean (more losing, p=0.000, 77 yr) [sedimentary plains/foothills: moderate groundwater connectivity -- gain/loss shifts can be real aquifer response; corroborate with nearby well records]
- BEAVER CREEK AT AVON, CO: reach shifted from -4 cfs to -222 cfs summer mean (more losing, p=0.000, 49 yr) [sedimentary uplands: moderate groundwater connectivity -- gain/loss shifts can be real aquifer response; corroborate with nearby well records] [measurement-evolution caution: this shift co-moves with the growth of the gage/metering network (rho=0.65) -- part of it may be unaccounted water becoming accounted, not hydrologic change]
- CROSS CREEK NEAR MINTURN, CO: reach shifted from +63 cfs to -94 cfs summer mean (more losing, p=0.000, 65 yr) [sedimentary uplands: moderate groundwater connectivity -- gain/loss shifts can be real aquifer response; corroborate with nearby well records]
- HOMESTAKE CREEK AT GOLD PARK, CO.: reach shifted from -461 cfs to +44 cfs summer mean (more gaining, p=0.043, 60 yr) [mountain crystalline canyon: minimal groundwater storage -- large or shifting unaccounted losses here are more consistent with data/measurement issues or unmodeled plumbing than with aquifer exchange]
Groundwater now has its own tab: 131 monitored well(s), water-table trends, stream corridors, and the advisory depletion screen.
Reservoirs now has its own tab: 69 reservoir(s), end-of-year storage back to 1951, click-to-chart histories.
Cross-gage pattern fingerprint
Over the 63-year window with full coverage (1964–2026), the dominant shared pattern across 3 gage(s) explains 71% 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.
Data provenance & quality
Where these numbers come from and how far they can be trusted. Grade D (2/6 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 45 day(s) old (target 7) |
| diversion record | stale | newest diversion record is 658 day(s) old (DWR publishes ~1 year in arrears) |
| structure coverage | sparse | 5% of schematic structures have data |
Independent check: PASS — 100.0000% agreement across 103,516 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 — 99.11% day-level agreement with USGS's own published records for the same gages, across 17 co-listed station(s) and 286,670 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.
23 gage(s) / 304,607 daily values (1910-10-01–2026-07-06); 521 structure(s) with diversion records; 2162 with decreed rights. Methodology has not yet had independent expert review — treat every figure as an advisory screen, not an administrative or legal conclusion.
273 water-level measurements across 131 monitored well(s) — 113 alluvial, 0 bedrock — plus 28 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.
Stream corridors — the surface connection
Where a reach's gain or loss has shifted, the wells within two miles of its anchoring gage and what their water table did over the same era.
How the corridor is assembled
For each reach whose gain/loss has shifted (Trends tab): the wells within 2 miles of its anchoring gage, their pooled water-table history over the same era, and an advisory Glover screen of lagged stream depletion from nearby metered pumping. v1 proximity = distance to the reach's anchoring gage; segment-based reach join is a flagged upgrade.
LAKE CREEK NEAR EDWARDS, CO: 18 alluvial well(s) nearby. Glover screen: 1.1 cfs of nearby metered alluvial pumping → est. lagged depletion 0.7–1.0 cfs (uncalibrated T/S ranges; flagged for SPDSS calibration, AWAS cross-check, and expert review — DWR's AWAS is the authority).
EAGLE RIVER BELOW GYPSUM, CO.: 10 alluvial well(s) nearby. Glover screen: 0.3 cfs of nearby metered alluvial pumping → est. lagged depletion 0.3–0.3 cfs (uncalibrated T/S ranges; flagged for SPDSS calibration, AWAS cross-check, and expert review — DWR's AWAS is the authority).
BEAVER CREEK AT AVON, CO: 1 alluvial well(s) nearby
CROSS CREEK NEAR MINTURN, CO: 3 alluvial well(s) nearby. Glover screen: 0.3 cfs of nearby metered alluvial pumping → est. lagged depletion 0.3–0.3 cfs (uncalibrated T/S ranges; flagged for SPDSS calibration, AWAS cross-check, and expert review — DWR's AWAS is the authority).
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.
69 reservoir(s) with 5,201 storage measurement(s), 1951–2025. Basin storage as of 2024-10-31 (the record's own end — reservoir records publish ~annually): 45,217 AF across 2 reservoir(s).
Why storage matters to the flow network
Storage change is real water the mass balance must credit — a losing reach beside a filling reservoir isn't losing water, it's banking it.
Reservoir map — how full is each vessel?
What “full” is measured against
Bubble size is proportional to a reservoir's record-high storage. Fill is its last recorded storage as a share of its surveyed capacity (USACE National Inventory of Dams) where a confident NID match exists — the tooltip names the matched dam — and as a share of its own record high otherwise. A wrong capacity would be worse than an honest record high, so only confident joins upgrade.
A dashed teal ring marks reservoirs reporting live DWR telemetry: their fill reflects yesterday's storage, is drawn as a dotted tail on charts, and is treated as provisional until the next verified HydroBase snapshot supersedes it.
Basin storage, end of each water year
End-of-water-year totals; per-year reservoir counts shown because reporting coverage varies -- a total is only comparable to years with similar counts.
Largest reservoirs on record
Click a reservoir to chart its full storage history.
| Reservoir | Last recorded storage (AF) | As of |
|---|---|---|
| ▸ HOMESTAKE PROJ RESERVOIR (3704516) | 42,078 | 2024-10-31 |
| ▸ HOMESTAKE RESERVOIR (3703519) | 38,278 | 1987-10-31 |
| ▸ EAGLE PARK RESERVOIR (3703699) | 3,138 | 2024-10-01 |
| ▸ ROBINSON RESERVOIR (3703527) | 1,967 | 2019-10-31 |
| ▸ BLACK LAKE (3703608) | 527 | 2019-10-31 |
| ▸ CHALK MOUNTAIN RESERVOIR (3703513) | 202 | 2019-10-31 |
| ▸ LEDE RESERVOIR (3703520) | 183 | 2020-06-11 |
| ▸ BLACK LAKE NO 2 (3703510) | 98 | 2019-10-31 |
Decreed rights on this network run from 1880-10-20 to 2024-12-31. 25 abandonment screens and 194 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: 4157 across 2162 structure(s); 100 structure(s) carry 0 court-case references. Advisory reading aids on public DWR data — not administrative or legal conclusions.
Abandonment radar (25 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 ~1951 — idleness that begins before then may be unreported use, not nonuse (flagged † below).
- OHNECK NO 2 DITCH (3700738) (1917-05-01, 2.3 cfs decreed): last active 1951 — 69 years idle
- PETERSON NO 4 DITCH (3700759) (1906-08-29, 0.2 cfs decreed): last active 1952 — 68 years idle
- SHIVELY DITCH (3700802) (1892-11-01, 1.2 cfs decreed): last active 1953 — 67 years idle
- BIGHORN PIPELINE (3700881) (1963-04-04, 1.6 cfs decreed): last active 1953 — 67 years idle
- MAHONEY DITCH (3700690) (1927-04-01, 2.8 cfs decreed): last active 1955 — 65 years idle
- NOTTINGHAM DITCH (93) (3700733) (1887-05-26, 2.0 cfs decreed): last active 1955 — 65 years idle
- BIG SPRING (3700879) (1935-05-01, 0.1 cfs decreed): last active 1955 — 65 years idle
- BEAVER MEADOWS DITCH (3700507) (1923-09-01, 1.1 cfs decreed): last active 1956 — 64 years idle
- JOHNSON & HOWARD DITCH (3700666) (1900-05-14, 3.0 cfs decreed): last active 1956 — 64 years idle
- WELLS NO 2 DITCH (3700852) (1930-05-01, 2.4 cfs decreed): last active 1956 — 64 years idle
Compliance screens (194 advisory flags)
Screened 369 of 2162 structures with rights (415 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.
- NOTTINGHAM & PUDER DITCH (3700736): Observed p99 daily rate 55.5 cfs (max 55.5) exceeds total decreed absolute 24.6 cfs across 11400 recorded day(s). Structure holds an Augmentation-use decree -- diversions above the direct-flow decree can be lawful under plan operations; interpret with care.
- COLUMBINE DITCH HDG 3 (3704641): Observed p99 daily rate 36.0 cfs (max 66.6) exceeds total decreed absolute 30.0 cfs across 22790 recorded day(s). Structure holds an Augmentation-use decree -- diversions above the direct-flow decree can be lawful under plan operations; interpret with care.
- BOLTS DITCH (3700514): Observed p99 daily rate 31.7 cfs (max 31.7) exceeds total decreed absolute 30.0 cfs across 4392 recorded day(s). Structure holds an Augmentation-use decree -- diversions above the direct-flow decree can be lawful under plan operations; interpret with care.
- TERRELL AND FORD DITCH (3700830): Observed p99 daily rate 27.6 cfs (max 31.5) exceeds total decreed absolute 23.8 cfs across 15370 recorded day(s).
- COWEN SPRINGS (3700558): Observed p99 daily rate 26.5 cfs (max 26.5) exceeds total decreed absolute 3.0 cfs across 3148 recorded day(s).
- CREAMERY DITCH (3700560): Observed p99 daily rate 26.5 cfs (max 28.8) exceeds total decreed absolute 21.6 cfs across 18331 recorded day(s). Structure holds an Augmentation-use decree -- diversions above the direct-flow decree can be lawful under plan operations; interpret with care.
- EMPIRE ZINC CO PIPELINE (3700590): Observed p99 daily rate 23.4 cfs (max 23.4) exceeds total decreed absolute 16.0 cfs across 4394 recorded day(s).
- EMPIRE ZINC CO PIPELINE (3700591): Observed p99 daily rate 23.4 cfs (max 23.4) exceeds total decreed absolute 1.0 cfs across 4392 recorded day(s).
- C K P DITCH (3700545): Observed p99 daily rate 22.6 cfs (max 30.1) exceeds total decreed absolute 2.4 cfs across 20209 recorded day(s). Structure holds an Augmentation-use decree -- diversions above the direct-flow decree can be lawful under plan operations; interpret with care.
- EAGLE DITCH (3700579): Observed p99 daily rate 21.2 cfs (max 21.2) exceeds total decreed absolute 13.2 cfs across 3240 recorded day(s).
Seniority (top structures by decreed rate)
| Structure | Senior priority date | Rights | Decreed abs (cfs) | Decreed abs (AF) | Conditional? |
|---|---|---|---|---|---|
| AVON WHITEWATER COURSE RICD BOB SR (3701416) | 2005-12-31 | 1 | 1400.0 | 0 | — |
| AVON WHITEWATER COURSE RICD BOB JR (3701417) | 2005-12-31 | 1 | 1400.0 | 0 | — |
| AVON WHITEWATER COURSE RICD BABY BOB (3701418) | 2005-12-31 | 1 | 1400.0 | 0 | — |
| TOWN OF VAIL WHITEWATER PARK STRUCTURE 1 (3701412) | 2000-10-10 | 1 | 810.0 | 0 | yes |
| TOWN OF VAIL WHITEWATER PARK STRUCTURE 2 (3701413) | 2000-10-10 | 1 | 756.0 | 0 | yes |
| TOWN OF VAIL WHITEWATER PARK STRUCTURE 3 (3701414) | 2000-10-10 | 1 | 719.0 | 0 | yes |
| HOMESTAKE PROJ TUNNEL (3704614) | 1952-09-22 | 1 | 300.0 | 0 | yes |
| HOMESTAKE PROJ CONDUIT-HOMESTAKE CREEK (3704643) | 1952-09-22 | 1 | 181.9 | 0 | yes |
| MIN FLOW EAGLE RIVER BRUSH CREEK TO COLO (3702012) | 1980-03-17 | 1 | 130.0 | 0 | — |
| MIN FLOW EAGLE RIVER LAKE CR TO BRUSH CR (3702059) | 1980-03-17 | 1 | 110.0 | 0 | — |
| MIN FLOW EAGLE RIVER GORE CR TO LAKE CR (3702041) | 1980-03-17 | 1 | 85.0 | 0 | — |
| WARREN E WURTS DITCH (3704648) | 1929-06-08 | 1 | 85.0 | 0 | — |
| HOMESTAKE PROJ CONDUIT-EAST FORK (3704644) | 1952-09-22 | 1 | 74.6 | 0 | yes |
| HOMESTAKE PROJ CONDUIT-FRENCH CREEK (3701253) | 1952-09-22 | 1 | 62.2 | 0 | yes |
| STRATTON AND CO DITCH (3700823) | 1881-07-01 | 14 | 54.4 | 0 | — |
No inventory or legal-document changes detected since the daily watch began.
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.