Computed 2026-08-20 09:18 from 53 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 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	13% of schematic structures have data

Independent check: PASS — 100.0000% agreement across 138,455 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 — 99.63% day-level agreement with USGS's own published records for the same gages, across 43 co-listed station(s) and 279,965 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.

53 gage(s) / 343,268 daily values (1902-04-01–2026-07-06); 1213 structure(s) with diversion records; 2166 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 320 structure(s) report in 2026, but structure reporting only reached half its modern level around ~1994. 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)
1900s	1	0
1910s	2	0
1920s	3	0
1930s	4	0
1940s	8	0
1950s	11	0
1960s	8	0
1970s	16	163
1980s	8	206
1990s	7	361
2000s	12	528
2010s	11	421
2020s	13	307

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
▸ BULL CREEK ABOVE SOUTH SIDE CANAL NR MOLINA☆ BULLCRCO	↓ decreasing	-128.2%	p=0.001	22	~2015
▸ ORCHARD MESA IRRIGATION DISTRICT ABOVE PALISADE☆ ORCHIDCO	↓ decreasing	-102.9%	p=0.014	27	~2006
▸ COTTONWOOD CREEK AT UPPER STA, NEAR MOLINA, CO.☆ COTAUPCO	↓ decreasing	-43.4%	p=0.024	13	~1949
▸ PLATEAU CREEK NEAR COLLBRAN, CO.☆ PLACOLCO	↓ decreasing	-24.0%	p=0.000	59	~1949
▸ MESA CREEK NEAR MESA, CO.☆ MESAMECO	↓ decreasing	-21.1%	p=0.021	20	—
▸ BUZZARD CREEK NEAR COLLBRAN, CO☆ BUZCOLCO	↓ decreasing	-15.6%	p=0.033	59	~1933
▸ REED WASH NEAR MACK, CO.☆ REEMACCO	↓ decreasing	-14.6%	p=0.007	25	—
▸ BIG CREEK AT UPPER STATION NEAR COLLBRAN☆ BIGUPPCO	↓ decreasing	-10.0%	p=0.001	20	~1955
▸ GOVERNMENT HIGHLINE CANAL NEAR CAMEO, CO☆ GHICANCO	↓ decreasing	-5.8%	p=0.000	40	~2004

44 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: 13% of 655 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 (1503 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.

• REED WASH NEAR MACK, CO.: reach shifted from -2542 cfs to -4818 cfs summer mean (more losing, p=0.006, 15 yr) [alluvial valley: real alluvial aquifer -- a decades-long shift toward losing is the classic signature of alluvial pumping and urbanization] [measurement-evolution caution: this shift co-moves with the growth of the gage/metering network (rho=-0.55) -- part of it may be unaccounted water becoming accounted, not hydrologic change]
• COLORADO RIVER NEAR COLORADO-UTAH STATE LINE: reach shifted from +9751 cfs to +5009 cfs summer mean (more losing, p=0.000, 76 yr) [sedimentary plains/foothills: moderate groundwater connectivity -- gain/loss shifts can be real aquifer response; corroborate with nearby well records]
• BIG SALT WASH AT FRUITA, CO.: reach shifted from -1490 cfs to -1490 cfs summer mean (more losing, p=0.016, 9 yr) [alluvial valley: real alluvial aquifer -- a decades-long shift toward losing is the classic signature of alluvial pumping and urbanization]
• GRAND VALLEY CANAL NEAR PALISADE, CO: reach shifted from -874 cfs to -109 cfs summer mean (more gaining, p=0.000, 41 yr) [alluvial valley: real alluvial aquifer -- a decades-long shift toward losing is the classic signature of alluvial pumping and urbanization]
• ORCHARD MESA IRRIGATION DISTRICT ABOVE PALISADE: reach shifted from -766 cfs to -734 cfs summer mean (more gaining, p=0.037, 27 yr) [alluvial valley: real alluvial aquifer -- a decades-long shift toward losing is the classic signature of alluvial pumping and urbanization] [measurement-evolution caution: this shift co-moves with the growth of the gage/metering network (rho=-0.5) -- part of it may be unaccounted water becoming accounted, not hydrologic change]

Groundwater now has its own tab: 31 monitored well(s), water-table trends, stream corridors, and the advisory depletion screen.

Reservoirs now has its own tab: 203 reservoir(s), end-of-year storage back to 1975, click-to-chart histories.

Cross-gage pattern fingerprint

Over the 41-year window with full coverage (1986–2026), the dominant shared pattern across 4 gage(s) explains 72% of year-to-year variance (almost certainly a basin-wide climate/snowpack driver).

GRDVALCO doesn'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.

Structures most implicated by reconciliation (as of 2026-07-06)

Which structures' data absorbed the most correction when the current mass-balance snapshot was reconciled -- see the Historical tab for the full picture on any date.

• PALISADE WW TRMT OUTFALL (return): -302.7 cfs (100% of that reach's correction)

The basin's aquifer story, from 97 water-level measurements across 31 monitored well(s) (12 alluvial, 1 bedrock, rest unclassified) — plus 35 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.

REED WASH NEAR MACK, CO.: 1 alluvial well(s) nearby

BIG SALT WASH AT FRUITA, CO.: 1 alluvial well(s) nearby. Glover screen: 0.0 cfs of nearby metered alluvial pumping → est. lagged depletion 0.0–0.0 cfs (uncalibrated T/S ranges; flagged for SPDSS calibration, AWAS cross-check, and expert review — DWR's AWAS is the authority).

GRAND VALLEY CANAL NEAR PALISADE, CO: 0 alluvial well(s) nearby. Glover screen: 0.2 cfs of nearby metered alluvial pumping → est. lagged depletion 0.1–0.2 cfs (uncalibrated T/S ranges; flagged for SPDSS calibration, AWAS cross-check, and expert review — DWR's AWAS is the authority).

ORCHARD MESA IRRIGATION DISTRICT ABOVE PALISADE: 0 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.

203 reservoir(s) with 46,798 storage measurement(s), 1975–2025. Basin storage as of 2024-10-31 (the record's own end — reservoir records publish ~annually): 7,207 AF across 38 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
▸ JERRY CREEK RESERVOIR TOTALIZER (7204128) ☆	6,936	2008-10-31
▸ JERRY CREEK RES NO 2 (7203962) ☆	6,527	2022-10-01
▸ VEGA RESERVOIR (7203844) ☆	4,336	2020-10-31
▸ HIGHLINE RESERVOIR (7203957) ☆	3,272	2015-10-12
▸ COTTONWOOD LAKES RES 1 (7203923) ☆	1,321	2024-10-28
▸ JERRY CREEK RES NO 1 (7203961) ☆	1,086	2022-10-01
▸ PALISADE CABIN RESERVOIR (7203854) ☆	985	2023-10-02
▸ BIG CREEK RESERVOIR NO 3 (7203905) ☆	941	2024-10-28

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: 2841 across 2166 structure(s); 22 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 ~1994 — idleness that begins before then may be unreported use, not nonuse (flagged † below).

• WEIMER DITCH (7200931)☆ (1915-05-25, 1.7 cfs decreed): last active 1970 — 44 years idle † predates modern reporting era — last recorded activity predates this basin's modern reporting era (~1994) -- early absence of record is weak evidence of nonuse
• PISEL DITCH (7200832)☆ (1905-02-07, 0.7 cfs decreed): last active 1977 — 37 years idle † predates modern reporting era — last recorded activity predates this basin's modern reporting era (~1994) -- early absence of record is weak evidence of nonuse
• LITTLE TRICKLE DITCH (7201298)☆ (1974-07-31, 0.1 cfs decreed): last active 1985 — 29 years idle † predates modern reporting era — last recorded activity predates this basin's modern reporting era (~1994) -- early absence of record is weak evidence of nonuse
• SCHORN COLLECTION D NO 2 (7201413)☆ (1935-06-01, 1.0 cfs decreed): last active 1985 — 29 years idle † predates modern reporting era — last recorded activity predates this basin's modern reporting era (~1994) -- early absence of record is weak evidence of nonuse
• BARKER PUMP AND PIPELINE (7200997)☆ (1941-04-01, 1.6 cfs decreed): last active 1986 — 28 years idle † predates modern reporting era — last recorded activity predates this basin's modern reporting era (~1994) -- early absence of record is weak evidence of nonuse
• CLEGHORN DRAIN DITCH NO2 (7201422)☆ (1972-02-01, 1.5 cfs decreed): last active 1987 — 27 years idle † predates modern reporting era — last recorded activity predates this basin's modern reporting era (~1994) -- early absence of record is weak evidence of nonuse
• OAK CREEK RES NO 1 (7204080)☆ (1946-05-01, 0.0 cfs decreed): last active 1987 — 27 years idle † predates modern reporting era — last recorded activity predates this basin's modern reporting era (~1994) -- early absence of record is weak evidence of nonuse
• HALL DITCH (BEAVER CR) (7200657)☆ (1914-05-01, 1.8 cfs decreed): last active 1988 — 26 years idle † predates modern reporting era — last recorded activity predates this basin's modern reporting era (~1994) -- early absence of record is weak evidence of nonuse
• HENDERSON WELL (7205040)☆ (1971-03-04, 0.0 cfs decreed): last active 1988 — 26 years idle † predates modern reporting era — last recorded activity predates this basin's modern reporting era (~1994) -- early absence of record is weak evidence of nonuse
• NICHOLS AND KNAPP WELL (7205050)☆ (1962-12-31, 0.0 cfs decreed): last active 1988 — 26 years idle † predates modern reporting era — last recorded activity predates this basin's modern reporting era (~1994) -- early absence of record is weak evidence of nonuse

Compliance screens (504 advisory flags)

Screened 775 of 2166 structures with rights (989 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.

• ROADSIDE MINE DEWAT SYS1 (7205407)☆: Observed p99 daily rate 137.3 cfs (max 137.8) exceeds total decreed absolute 0.6 cfs across 367 recorded day(s).
• PARK CREEK DITCH (PARK) (7200819)☆: Observed p99 daily rate 56.0 cfs (max 102.0) exceeds total decreed absolute 6.5 cfs across 18283 recorded day(s).
• UTE PIPELINE HGT NO 1 (7201487)☆: Observed p99 daily rate 48.2 cfs (max 3473.1) exceeds total decreed absolute 30.0 cfs across 30181 recorded day(s).
• HARTMAN DIVERSION-WEBB (7201753)☆: Observed p99 daily rate 38.0 cfs (max 38.0) exceeds total decreed absolute 0.2 cfs across 304 recorded day(s).
• OWENS CREEK DITCH (7204721)☆: Observed p99 daily rate 24.2 cfs (max 33.1) exceeds total decreed absolute 18.9 cfs across 6799 recorded day(s).
• ANDERSON FEEDER DITCH (7200506)☆: Observed p99 daily rate 22.7 cfs (max 22.7) exceeds total decreed absolute 22.7 cfs across 1802 recorded day(s).
• PALMER DITCH (7200818)☆: Observed p99 daily rate 20.8 cfs (max 31.7) exceeds total decreed absolute 20.2 cfs across 29152 recorded day(s).
• BULL ELK DITCH (7200559)☆: Observed p99 daily rate 19.5 cfs (max 19.5) exceeds total decreed absolute 19.1 cfs across 4420 recorded day(s).
• BULL CREEK DITCH (7200558)☆: Observed p99 daily rate 17.9 cfs (max 23.3) exceeds total decreed absolute 16.4 cfs across 38749 recorded day(s).
• R M G DITCH (7200852)☆: Observed p99 daily rate 16.4 cfs (max 16.6) exceeds total decreed absolute 15.8 cfs across 5748 recorded day(s).

Seniority (top structures by decreed rate)

Structure	Senior priority date	Rights	Decreed abs (cfs)	Decreed abs (AF)	Conditional?
GRAND VALLEY PROJECT (7200646)☆	1889-10-01	7	2313.7	0	—
GRAND VALLEY CANAL (7200645)☆	1882-08-22	5	940.3	0	—
MIN FLOW COLORADO RIVER USFW (7202003)☆	1992-03-05	2	881.0	0	—
MESA CO IRR DIST CANAL (7200783)☆	1903-07-06	1	667.0	0	—
PALISADE IRR DIST CANAL (7200817)☆	1889-10-01	1	573.0	0	—
LEON PARK FEEDER CANAL (7200746)☆	1952-08-19	2	450.0	0	—
SOUTHSIDE CANAL (7200879)☆	1952-08-19	1	240.0	0	—
PARK CREEK DITCH (VEGA) (7200820)☆	1963-08-16	1	100.0	0	—
LEON TUNNEL CANAL (7204715)☆	1900-06-12	1	54.0	0	—
BONHAM BRANCH PIPELINE (7200542)☆	1952-08-19	1	45.0	0	—
NEW ERIE CANAL (7200616)☆	1906-06-01	7	36.4	0	—
MORMON MESA DITCH (7200799)☆	1888-01-12	8	34.0	0	—
SILVER GAUGE DITCH (7200870)☆	1888-08-10	5	32.6	0	—
KIGGINS SALISBURY DITCH (7200730)☆	1900-08-12	3	31.3	0	—
EAST FORK FEEDER CANAL (7200609)☆	1952-08-19	1	30.0	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.