Computed 2026-08-20 08:51 from 20 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	12% of schematic structures have data

Independent check: PASS — 100.0000% agreement across 102,978 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 — 100.00% day-level agreement with USGS's own published records for the same gages, across 8 co-listed station(s) and 47,071 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.

20 gage(s) / 185,633 daily values (1923-06-01–2026-07-06); 203 structure(s) with diversion records; 847 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. 14 gage(s) and 99 structure(s) report in 2026, but structure reporting only reached half its modern level around ~1969. 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	2	0
1940s	2	0
1950s	2	44
1960s	2	56
1970s	2	74
1980s	4	95
1990s	2	74
2000s	13	116
2010s	14	118
2020s	13	99

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
▸ MAJOR CREEK NEAR VILLA GROVE☆ MAJVILCO	no clear trend	+16.5%	p=0.119	28	~2006
▸ COTTONWOOD CREEK NEAR CRESTONE, CO.☆ COCRESCO	↓ decreasing	-7.5%	p=0.012	32	—
▸ KERBER CREEK NEAR VILLA GROVE☆ KERVILCO	↓ decreasing	-4.8%	p=0.001	84	~1999
▸ CRESTONE CREEK, NORTH NEAR CRESTONE☆ NOCRESCO	no clear trend	-2.5%	p=0.074	91	~1999

16 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: 12% of 273 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 (1951–2026)

Mass-balance kinks computed for every summer month back to 1951 (479 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: 206 monitored well(s), water-table trends, stream corridors, and the advisory depletion screen.

Cross-gage pattern fingerprint

Over the 28-year window with full coverage (1999–2026), the dominant shared pattern across 11 gage(s) explains 50% of year-to-year variance (almost certainly a basin-wide climate/snowpack driver).

CHECRECO, COCRESCO, GARVILCO, MAJVILCO, SPACRECO don't move with that shared pattern -- a real, localized signal (a new diversion, land-use change, or a gage-specific data problem) worth a closer look, not necessarily noise.

The basin's aquifer story, from 19,132 water-level measurements across 206 monitored well(s) (70 alluvial, 62 bedrock, rest unclassified) — plus 1 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 71 well(s) with enough record for a trend test: 41 declining, 6 rising.

Fastest-declining wells	Setting	ft / decade	Span	p
▸ NA04101003AAA2 EW-46C☆	alluvial	-7.66	11 yr	0.002
▸ NA04001106DAD EW-71C☆	alluvial	-4.27	26 yr	0.0145
▸ BACA-2☆	unknown	-4.16	19 yr	0.0
▸ NA04201027DAD2 EW-52C☆	alluvial	-3.94	11 yr	0.0049
▸ NA04501007CCA RG02 ☆	unknown	-3.26	46 yr	0.0
▸ NA04101013ABD1 EW-79C☆	alluvial	-3.25	35 yr	0.0001
▸ NA04301028BBB2 EW-62C☆	unknown	-2.83	11 yr	0.0001
▸ NA04101002ABA RG24A☆	alluvial	-2.81	45 yr	0.0

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.

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: 1024 across 847 structure(s); 41 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 ~1969 — idleness that begins before then may be unreported use, not nonuse (flagged † below).

• BARSCH D 1 (2500528)☆ (1881-04-15, 1.6 cfs decreed): last active 1961 — 64 years idle † predates modern reporting era — last recorded activity predates this basin's modern reporting era (~1969) -- early absence of record is weak evidence of nonuse
• HOFFMAN D 2 (2500604)☆ (1875-05-01, 0.9 cfs decreed): last active 1961 — 64 years idle † predates modern reporting era — last recorded activity predates this basin's modern reporting era (~1969) -- early absence of record is weak evidence of nonuse
• BACA GRANT 4 IRR D 19 (2500518)☆ (1870-05-10, 39.8 cfs decreed): last active 1968 — 57 years idle † predates modern reporting era — last recorded activity predates this basin's modern reporting era (~1969) -- early absence of record is weak evidence of nonuse
• BRALEY D (2500530)☆ (1886-05-09, 1.4 cfs decreed): last active 1973 — 52 years idle
• JOHN DECAMP D B (2500610)☆ (1884-06-01, 0.6 cfs decreed): last active 1975 — 50 years idle
• KAUFMAN D (2500611)☆ (1883-05-10, 1.0 cfs decreed): last active 1980 — 45 years idle
• DRISCOLL D (2500565)☆ (1908-09-28, 1.8 cfs decreed): last active 1984 — 41 years idle
• CEDAR CR D (2500533)☆ (1910-03-01, 2.0 cfs decreed): last active 1986 — 39 years idle
• NORTH,MIDDLE & TOP SPGS (2500743)☆ (1871-05-01, 1.0 cfs decreed): last active 1989 — 36 years idle
• DRISCOLL D 2 (2500566)☆ (1909-04-15, 3.0 cfs decreed): last active 1990 — 35 years idle

Compliance screens (107 advisory flags)

Screened 145 of 847 structures with rights (151 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.

• BACA GRANT 4 IRR D 9 (2500513)☆: Observed p99 daily rate 70.0 cfs (max 90.6) exceeds total decreed absolute 39.0 cfs across 10906 recorded day(s).
• BACA GRANT 4 IRR D 10 (2500514)☆: Observed p99 daily rate 41.0 cfs (max 41.0) exceeds total decreed absolute 39.4 cfs across 1308 recorded day(s).
• WALES SHELLABARGER D 2 (2500678)☆: Observed p99 daily rate 37.5 cfs (max 54.0) exceeds total decreed absolute 37.0 cfs across 23396 recorded day(s).
• SHELLABARGER HOME D 2 (2500651)☆: Observed p99 daily rate 28.0 cfs (max 28.8) exceeds total decreed absolute 3.0 cfs across 476 recorded day(s).
• STEEL D 2 (2500661)☆: Observed p99 daily rate 21.5 cfs (max 37.8) exceeds total decreed absolute 7.6 cfs across 28637 recorded day(s).
• BACA GRANT 4 IRR D 3 (2500507)☆: Observed p99 daily rate 20.0 cfs (max 30.0) exceeds total decreed absolute 4.0 cfs across 5374 recorded day(s).
• SAN ISABEL D (2500640)☆: Observed p99 daily rate 20.0 cfs (max 35.0) exceeds total decreed absolute 19.8 cfs across 5168 recorded day(s).
• BACA GRANT 4 IRR D 5 (2500509)☆: Observed p99 daily rate 18.0 cfs (max 29.0) exceeds total decreed absolute 5.8 cfs across 3798 recorded day(s).
• PETERSON D 1 (2500628)☆: Observed p99 daily rate 18.0 cfs (max 50.0) exceeds total decreed absolute 14.9 cfs across 15772 recorded day(s).
• BACA GRANT 4 IRR D 4 (2500508)☆: Observed p99 daily rate 15.0 cfs (max 22.0) exceeds total decreed absolute 7.0 cfs across 8360 recorded day(s).

Seniority (top structures by decreed rate)

Structure	Senior priority date	Rights	Decreed abs (cfs)	Decreed abs (AF)	Conditional?
COTTONWOOD CR D (2500550)☆	1870-05-10	1	94.4	0	—
USFS QP55A1 (2500920)☆	1902-04-11	1	90.2	0	—
HOFFMAN NEIDHARDT D (2500698)☆	1868-03-15	12	69.1	0	—
WILLOW CR D (2500684)☆	1870-05-10	1	69.0	0	—
BACA GRANT 4 IRR D 12 (2500516)☆	1870-05-01	6	44.2	0	—
BACA GRANT 4 IRR D 19 (2500518)☆	1870-05-10	1	39.8	0	—
BACA GRANT 4 IRR D 10 (2500514)☆	1870-07-01	2	39.4	0	—
BACA GRANT 4 IRR D 9 (2500513)☆	1870-05-01	2	39.0	0	—
BACA GRANT 4 IRR D 24 (2500520)☆	1870-05-10	2	39.0	0	—
WALES SHELLABARGER D 2 (2500678)☆	1870-07-01	6	37.0	0	—
USFS QP53H2 (2500915)☆	1902-04-11	1	30.6	0	—
USFS QP53G6 (2500913)☆	1902-04-11	1	28.8	0	—
ARTHUR YOUNG D (2500505)☆	1876-04-01	2	28.0	0	—
JK HR COLE DR SPG WW D 1 (2500734)☆	1952-08-20	1	25.7	0	—
BACA GRANT 4 IRR D 25 (2500521)☆	1870-05-10	1	24.0	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.