Computed 2026-08-20 09:03 from 14 gage(s) with cached period-of-record data. Statistical tests (Mann-Kendall trend, Pettitt changepoint) require at least 8 years spanning at least 10 years of record -- gages below that report no signal, not "no change."

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 45 day(s) old (target 7)
diversion record	expected-lag	newest diversion record is 293 day(s) old (DWR publishes ~1 year in arrears)
structure coverage	sparse	10% of schematic structures have data

Independent check: PASS — 100.0000% agreement across 90,343 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 — 98.21% day-level agreement with USGS's own published records for the same gages, across 10 co-listed station(s) and 129,441 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.

14 gage(s) / 135,243 daily values (1910-10-01–2026-07-06); 323 structure(s) with diversion records; 1980 with decreed rights. Methodology has not yet had independent expert review — treat every figure as an advisory screen, not an administrative or legal conclusion.

Read this first: the measurement network itself evolved

This basin was not always measured the way it is today — the API-era record is dense and recent, the early record sparse. 6 gage(s) and 164 structure(s) report in 2026, but structure reporting only reached half its modern level around ~1986. 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
1930s	1	0
1940s	5	0
1950s	4	0
1960s	3	0
1970s	3	74
1980s	4	75
1990s	3	130
2000s	3	191
2010s	5	195
2020s	6	159

Gage flow trend & changepoints

Every located gage with a period of record — dot size scales with the strength of its flow trend (|Sen slope| in %/decade, the same statistic as the table below), color with direction. An amber ring marks a detected Pettitt changepoint. Click a gage to chart its trend and shift.

Gage	Trend	Change / decade	Significance	Years	Changepoint
▸ CIMARRON RIVER BLW SQUAW CREEK AT CIMARRON, CO☆ CIMSQWCO	↓ decreasing	-49.1%	p=0.001	26	~2017
▸ CIMARRON RIVER NEAR CIMARRON, CO☆ CIMCIMCO	no clear trend	-2.8%	p=0.070	72	~1987

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

Mass-balance (network closure) trend

Structure divrec-history backfill coverage as of the last check: 10% of 639 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 (1982–2026)

Mass-balance kinks computed for every summer month back to 1982 (103 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 FORK AT GATEVIEW, CO.: reach shifted from +365 cfs to +213 cfs summer mean (more losing, p=0.005, 16 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: 19 monitored well(s), water-table trends, stream corridors, and the advisory depletion screen.

Reservoirs now has its own tab: 9 reservoir(s), end-of-year storage back to 1975, click-to-chart histories.

Cross-gage pattern fingerprint

Over the 72-year window with full coverage (1955–2026), the dominant shared pattern across 3 gage(s) explains 62% 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.

The basin's aquifer story, from 43 water-level measurements across 19 monitored well(s) (18 alluvial, 0 bedrock, rest unclassified) — plus 0 administered well(s) reporting metered pumping through diversion records. Observation wells and pumping wells are different populations and are never conflated. Click a well to chart its record.

Well map

Every monitored well with a location — hover for identity, click to chart its water-level record below. ● alluvial   ● bedrock / confined (Denver Basin, High Plains, etc. — one-way, no human-timescale recharge)   ● unclassified — marker size scales with the strength of the well's water-level trend (|Sen slope| in ft/decade — the same Mann-Kendall/Sen statistic as the trends table below); the smallest, faintest dots have too little record to test.

3D aquifer x-ray

Every aquifer unit as its own 3D head surface — alluvial water table on top, Denver Basin members (Dawson, Denver, Arapahoe, Laramie–Fox Hills) stacked beneath where measured — interpolated from measured water levels and animated through time. Units are never mixed; surfaces exist only inside each unit's well coverage (no extrapolation); thin epochs are suppressed with their reason shown. Vertical scale exaggerated for readability; z is head elevation in feet. Advisory — measured heads, not a calibrated model.

Load 3D x-ray

Water-table trends

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

Stream corridors — the surface connection

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 FORK AT GATEVIEW, CO.: 1 alluvial well(s) nearby

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.

9 reservoir(s) with 7,860 storage measurement(s), 1975–2026. Basin storage as of 2025-10-31 (the record's own end — reservoir records publish ~annually): 128,266 AF across 3 reservoir(s). 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?

Each reservoir drawn as a vessel: bubble size ∝ its record-high storage, fill level = 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 of its own record high otherwise (a wrong capacity would be worse than an honest record high, so only confident joins upgrade). Hover for numbers, click to chart its history below the map. A dashed teal ring marks reservoirs reporting live DWR telemetry — their fill reflects yesterday's storage, drawn as a dotted tail on charts and treated as provisional until the next verified HydroBase snapshot supersedes it. ● <25% ● 25–60% ● 60–90% ● >90%

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
▸ MORROW POINT RESERVOIR (6203545) ☆	110,736	2025-10-31
▸ CRYSTAL RESERVOIR (6203578) ☆	15,982	2025-10-31
▸ SILVER JACK RESERVOIR (6203548) ☆	1,548	2025-10-31
▸ LAKE SAN CRISTOBAL (6203542) ☆	517	2018-10-29
▸ FISH CREEK RES NO 2 (6203539) ☆	284	2023-06-22
▸ SODERQUIST RES (6203549) ☆	165	1975-08-07
▸ FISH CREEK RES NO 1 (6203538) ☆	150	1975-08-07
▸ MCKINLEY DITCH (6200672) ☆	63	2004-06-30

Decrees, seniority, and administrative calls connected to this basin's flow network. Advisory reading aids on public DWR data — not administrative or legal conclusions. Rights on file: 2280 across 1980 structure(s); 73 structure(s) carry 0 court-case references.

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 ~1986 — idleness that begins before then may be unreported use, not nonuse (flagged † below).

• MAURER TOPLISS DRAW D (6200668)☆ (1913-05-01, 2.0 cfs decreed): last active 1974 — 50 years idle † predates modern reporting era — last recorded activity predates this basin's modern reporting era (~1986) -- early absence of record is weak evidence of nonuse
• FISH CREEK RES NO 1 (6203538)☆ (1904-07-06, 0.0 cfs decreed): last active 1974 — 50 years idle † predates modern reporting era — last recorded activity predates this basin's modern reporting era (~1986) -- early absence of record is weak evidence of nonuse
• AUSTIN SPRING NO 2 DITCH (6200514)☆ (1928-06-10, 0.0 cfs decreed): last active 1981 — 43 years idle † predates modern reporting era — last recorded activity predates this basin's modern reporting era (~1986) -- early absence of record is weak evidence of nonuse
• CEBOLLA CREEK (6200579)☆ (1980-09-09, 4.0 cfs decreed): last active 1982 — 42 years idle † predates modern reporting era — last recorded activity predates this basin's modern reporting era (~1986) -- early absence of record is weak evidence of nonuse
• ORME DITCH NO 1 (6200700)☆ (1947-06-01, 2.0 cfs decreed): last active 1986 — 38 years idle
• ORME DITCH NO 2 (6200701)☆ (1948-06-09, 1.5 cfs decreed): last active 1986 — 38 years idle
• ORME DITCH NO 3 (6200702)☆ (1948-06-09, 0.5 cfs decreed): last active 1986 — 38 years idle
• HOFMANN SPG & DOM PL (6200984)☆ (1950-06-15, 0.2 cfs decreed): last active 1987 — 37 years idle
• HOFMANN SPG NO 5 & PL (6200985)☆ (1971-09-15, 0.0 cfs decreed): last active 1987 — 37 years idle
• BRUTON DITCH NO 1 (6200538)☆ (1912-07-01, 0.8 cfs decreed): last active 1989 — 35 years idle

Compliance screens (179 advisory flags)

Screened 257 of 1980 structures with rights (274 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.

• GUNNISON TUNNEL AND SOUTH CANAL (6200617)☆: Observed p99 daily rate 1351.0 cfs (max 2672.0) exceeds total decreed absolute 1175.0 cfs across 26883 recorded day(s).
• BIG DITCH (6200529)☆: Observed p99 daily rate 48.2 cfs (max 51.6) exceeds total decreed absolute 33.0 cfs across 6770 recorded day(s).
• FRANK ADAMS D NO 2 (6200605)☆: Observed p99 daily rate 48.0 cfs (max 53.9) exceeds total decreed absolute 38.5 cfs across 9646 recorded day(s).
• BROWNING DITCH (6200536)☆: Observed p99 daily rate 44.0 cfs (max 53.2) exceeds total decreed absolute 6.0 cfs across 8258 recorded day(s).
• COOPER NO 2 D (6200569)☆: Observed p99 daily rate 44.0 cfs (max 59.1) exceeds total decreed absolute 26.5 cfs across 8044 recorded day(s).
• GEORGE ANDREWS NO 1 D (6200612)☆: Observed p99 daily rate 42.6 cfs (max 42.6) exceeds total decreed absolute 13.6 cfs across 7926 recorded day(s).
• M B & A DITCH (6200670)☆: Observed p99 daily rate 37.0 cfs (max 41.2) exceeds total decreed absolute 27.8 cfs across 7582 recorded day(s).
• MCKINLEY DITCH (6200672)☆: Observed p99 daily rate 36.0 cfs (max 38.0) exceeds total decreed absolute 31.0 cfs across 17757 recorded day(s).
• SOUTH BEAVER CREEK DITCH (6200754)☆: Observed p99 daily rate 35.5 cfs (max 35.5) exceeds total decreed absolute 0.8 cfs across 3842 recorded day(s).
• YOUMANS IRG D NO 1 (6200809)☆: Observed p99 daily rate 34.3 cfs (max 47.8) exceeds total decreed absolute 0.3 cfs across 3318 recorded day(s). Structure holds an Augmentation-use decree -- diversions above the direct-flow decree can be lawful under plan operations; interpret with care.

Seniority (top structures by decreed rate)

Structure	Senior priority date	Rights	Decreed abs (cfs)	Decreed abs (AF)	Conditional?
MORROW POINT POWER PLANT (6200692)☆	1957-11-13	2	5450.0	0	—
BLUE MESA POWER PLANT (6200533)☆	1957-11-13	2	3500.0	0	—
CRYSTAL POWER PLANT (6200578)☆	1957-11-13	2	3000.0	0	yes
GUNNISON TUNNEL AND SOUTH CANAL (6200617)☆	1901-06-01	4	1175.0	0	yes
GUNNISON RIVER (NAT PARK) (6201498)☆	1933-03-02	1	300.0	0	—
GUNNISON RIVER (CWCB) (6201540)☆	1965-12-10	1	300.0	0	—
CIMARRON CANAL (6200560)☆	1903-04-01	3	185.0	0	—
CROOKE'S FALLS FLUME (6201489)☆	1983-03-15	1	121.0	0	—
BIG BLUE DITCH (6200528)☆	1904-06-01	4	66.0	0	—
CIMARRON FEEDER GARNET DITCH (6200561)☆	1890-08-01	1	50.0	0	—
LAKE FORK GUNNISON RIVER (6201331)☆	1980-03-17	1	45.0	0	—
FRANK ADAMS D NO 2 (6200605)☆	1880-09-01	7	38.5	0	—
LAKE FORK GUNNISON RIVER (6201442)☆	1980-03-17	1	35.0	0	—
BIG DITCH (6200529)☆	1876-06-01	3	33.0	0	—
SWANK FISH POND D NO 2 (6200769)☆	1910-05-01	3	33.0	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.

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

Administration number
Simulate

DWR administration numbers encode appropriation and adjudication dates; lower is more senior.