Computed 2026-08-20 09:10 from 72 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	4% of schematic structures have data

Independent check: PASS — 100.0000% agreement across 130,642 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 — 99.94% day-level agreement with USGS's own published records for the same gages, across 60 co-listed station(s) and 389,031 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.

72 gage(s) / 552,097 daily values (1906-04-01–2026-07-06); 899 structure(s) with diversion records; 4788 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. 22 gage(s) and 263 structure(s) report in 2026, but structure reporting only reached half its modern level around ~1975. 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	8	0
1920s	1	0
1930s	2	0
1940s	4	0
1950s	9	42
1960s	22	68
1970s	26	230
1980s	20	326
1990s	19	307
2000s	21	204
2010s	23	254
2020s	22	262

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
▸ IVANHOE CREEK NEAR NORRIE, CO.☆ IVANORCO	↓ decreasing	-62.8%	p=0.044	13	—
▸ NF FRYINGPAN R AB CUNNINGHAM C, NR NORRIE, CO.☆ NOFRYACO	↓ decreasing	-58.8%	p=0.003	17	~1973
▸ CUNNINGHAM CREEK NEAR NORRIE, CO.☆ CUNNORCO	↓ decreasing	-50.5%	p=0.006	17	~1973
▸ SNOWMASS CREEK☆ SNOCRECO	↓ decreasing	-30.6%	p=0.008	27	~2017
▸ ROARING FORK RIVER AB DIFFICULT C NR ASPEN, CO.☆ ROADIFCO	↓ decreasing	-18.0%	p=0.000	47	~2000
▸ CRYSTAL RIVER NEAR REDSTONE, CO.☆ CRYREDCO	↓ decreasing	-10.0%	p=0.012	28	—
▸ FRYINGPAN RIVER NEAR IVANHOE LAKE, CO.☆ FRYIVLCO	↓ decreasing	-10.0%	p=0.016	62	~1971
▸ FRYINGPAN RIVER AT NORRIE, CO.☆ FRYANOCO	↓ decreasing	-9.5%	p=0.000	42	~1972
▸ FRYINGPAN RIVER NEAR RUEDI, CO.☆ FRYRUDCO	↓ decreasing	-7.9%	p=0.001	62	~1999
▸ ROCKY FORK CREEK NEAR MEREDITH, CO.☆ RFCMERCO	↓ decreasing	-7.8%	p=0.000	58	~1999
▸ MAROON CREEK ABOVE ASPEN, CO.☆ MARASPCO	no clear trend	+7.7%	p=0.234	25	~1981
▸ ROARING FORK RIVER NEAR ASPEN, CO.☆ ROAASPCO	↓ decreasing	-4.9%	p=0.020	62	~2000
▸ MAROON CREEK NEAR ASPEN, CO.☆ MARNASCO	↓ decreasing	-4.4%	p=0.016	14	—
▸ SOUTH FORK FRYINGPAN RIVER AT UPPER STATION NEAR NORRIE☆ FRYSFUCO	no clear trend	+2.8%	p=0.275	63	~1971
▸ ROARING FORK RIVER AT GLENWOOD SPRINGS, CO.☆ ROAGLECO	↓ decreasing	-2.1%	p=0.002	120	~1930
▸ CHAPMAN GULCH NEAR NAST, CO.☆ CHAGULCO	no clear trend	+0.6%	p=0.896	53	~1980

56 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: 4% of 1922 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 (2628 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.

• CRYSTAL RIVER AT PLACITA, CO.: reach shifted from +123 cfs to +180 cfs summer mean (more gaining, p=0.011, 12 yr) [alluvial valley: real alluvial aquifer -- a decades-long shift toward losing is the classic signature of alluvial pumping and urbanization]
• ROARING FORK RIVER AT GLENWOOD SPRINGS, CO.: reach shifted from +2386 cfs to +1075 cfs summer mean (more losing, p=0.000, 77 yr) [alluvial valley: real alluvial aquifer -- a decades-long shift toward losing is the classic signature of alluvial pumping and urbanization]
• CRYSTAL RIVER ABV AVALANCHE CRK, NEAR REDSTONE, CO: reach shifted from +295 cfs to -136 cfs summer mean (more losing, p=0.000, 63 yr) [sedimentary uplands: moderate groundwater connectivity -- gain/loss shifts can be real aquifer response; corroborate with nearby well records]
• HUNTER CREEK AT ASPEN, CO: reach shifted from -54 cfs to -104 cfs summer mean (more losing, p=0.004, 17 yr) [sedimentary uplands: moderate groundwater connectivity -- gain/loss shifts can be real aquifer response; corroborate with nearby well records]
• MAROON CREEK ABOVE ASPEN, CO.: reach shifted from +17 cfs to +59 cfs summer mean (more gaining, p=0.011, 26 yr) [sedimentary uplands: moderate groundwater connectivity -- gain/loss shifts can be real aquifer response; corroborate with nearby well records]
• HUNTER CREEK NEAR ASPEN, CO: reach shifted from -27 cfs to -111 cfs summer mean (more losing, p=0.046, 48 yr) [alluvial valley: real alluvial aquifer -- a decades-long shift toward losing is the classic signature of alluvial pumping and urbanization]

Groundwater now has its own tab: 46 monitored well(s), water-table trends, stream corridors, and the advisory depletion screen.

Reservoirs now has its own tab: 165 reservoir(s), end-of-year storage back to 1953, 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 65% of year-to-year variance (almost certainly a basin-wide climate/snowpack driver).

FRYSFUCO 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.

• WHITMER D & PD PR STO RT (return): -83.7 cfs (100% of that reach's correction)

The basin's aquifer story, from 149 water-level measurements across 46 monitored well(s) (19 alluvial, 0 bedrock, rest unclassified) — plus 28 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.

CRYSTAL RIVER AT PLACITA, CO.: 0 alluvial well(s) nearby

CRYSTAL RIVER ABV AVALANCHE CRK, NEAR REDSTONE, CO: 1 alluvial well(s) nearby. Glover screen: 0.1 cfs of nearby metered alluvial pumping → est. lagged depletion 0.0–0.1 cfs (uncalibrated T/S ranges; flagged for SPDSS calibration, AWAS cross-check, and expert review — DWR's AWAS is the authority).

HUNTER CREEK AT ASPEN, CO: 0 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).

HUNTER CREEK NEAR ASPEN, CO: 0 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).

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.

165 reservoir(s) with 7,787 storage measurement(s), 1953–2025. Basin storage as of 2024-10-31 (the record's own end — reservoir records publish ~annually): 79,357 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
▸ RUEDI RESERVOIR (3803713) ☆	78,521	2024-10-31
▸ WILDCAT RESERVOIR (3803759) ☆	1,140	2005-10-31
▸ MESA RESERVOIR (3803738) ☆	848	1985-10-31
▸ IVANHOE RESERVOIR (3803732) ☆	836	2024-10-31
▸ ALICIA LAKE RESERVOIR (3803711) ☆	673	2010-05-25
▸ SPRING PARK RESERVOIR (3803744) ☆	332	2022-08-14
▸ WOODS LAKE RESERVOIR (3803760) ☆	300	2005-10-31
▸ JACOBSON LAKES & PONDS (3803832) ☆	225	2002-10-31

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: 6580 across 4788 structure(s); 377 structure(s) carry 0 court-case references.

Abandonment radar (9 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 ~1975 — idleness that begins before then may be unreported use, not nonuse (flagged † below).

• CASTLE CREEK DITCH (3800576)☆ (1884-08-15, 2.0 cfs decreed): last active 1956 — 29 years idle † predates modern reporting era — last recorded activity predates this basin's modern reporting era (~1975) -- early absence of record is weak evidence of nonuse
• PRINCE DITCH (3800948)☆ (1982-05-15, 13.4 cfs decreed): last active 1961 — 24 years idle † predates modern reporting era — last recorded activity predates this basin's modern reporting era (~1975) -- early absence of record is weak evidence of nonuse
• FISHER AND HAFF DITCH (3800677)☆ (1901-10-29, 2.0 cfs decreed): last active 1962 — 23 years idle † predates modern reporting era — last recorded activity predates this basin's modern reporting era (~1975) -- early absence of record is weak evidence of nonuse
• RED MOUNTAIN DITCH (3800955)☆ (1884-05-15, 0.1 cfs decreed): last active 1968 — 17 years idle † predates modern reporting era — last recorded activity predates this basin's modern reporting era (~1975) -- early absence of record is weak evidence of nonuse
• EAGLE DITCH (3800647)☆ (1888-03-17, 0.6 cfs decreed): last active 1969 — 16 years idle † predates modern reporting era — last recorded activity predates this basin's modern reporting era (~1975) -- early absence of record is weak evidence of nonuse
• GLENWOOD DITCH CATTLE CR (3800711)☆ (1900-11-18, 2.0 cfs decreed): last active 1969 — 16 years idle † predates modern reporting era — last recorded activity predates this basin's modern reporting era (~1975) -- early absence of record is weak evidence of nonuse
• ROBERTS DITCH (3800965)☆ (1888-09-04, 6.1 cfs decreed): last active 1975 — 10 years idle
• RUEDI DITCH (3800977)☆ (1887-05-15, 2.3 cfs decreed): last active 1975 — 10 years idle
• EARL V NELSON MTN CR RCH SPRING (3801089)☆ (1953-06-30, 0.1 cfs decreed): last active 1975 — 10 years idle

Compliance screens (373 advisory flags)

Screened 696 of 4788 structures with rights (784 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.

• RUEDI RESERVOIR PWR PL (3801360)☆: Observed p99 daily rate 320.9 cfs (max 507.0) exceeds total decreed absolute 300.0 cfs across 47812 recorded day(s).
• IND P TM DVR LOST MAN (3801767)☆: Observed p99 daily rate 192.6 cfs (max 242.8) exceeds total decreed absolute 21.3 cfs across 8895 recorded day(s).
• PATERSON D JACOB EXT (3800930)☆: Observed p99 daily rate 118.9 cfs (max 218.1) exceeds total decreed absolute 63.0 cfs across 28936 recorded day(s).
• MOUNTAIN MEADOWS DITCH (3800881)☆: Observed p99 daily rate 100.0 cfs (max 146.9) exceeds total decreed absolute 53.0 cfs across 23772 recorded day(s).
• SALVATION DITCH (3800981)☆: Observed p99 daily rate 96.0 cfs (max 110.0) exceeds total decreed absolute 59.0 cfs across 24051 recorded day(s). Structure holds an Augmentation-use decree -- diversions above the direct-flow decree can be lawful under plan operations; interpret with care.
• HOME SUPPLY DITCH (3800757)☆: Observed p99 daily rate 90.6 cfs (max 94.8) exceeds total decreed absolute 59.0 cfs across 19551 recorded day(s).
• IVANHOE RESERVOIR TUNNEL (3804613)☆: Observed p99 daily rate 69.0 cfs (max 132.0) exceeds total decreed absolute 35.0 cfs across 48796 recorded day(s). Structure holds an Augmentation-use decree -- diversions above the direct-flow decree can be lawful under plan operations; interpret with care.
• GLENWOOD DITCH (3800712)☆: Observed p99 daily rate 60.0 cfs (max 62.4) exceeds total decreed absolute 45.9 cfs across 23043 recorded day(s). Structure holds an Augmentation-use decree -- diversions above the direct-flow decree can be lawful under plan operations; interpret with care.
• ROBINSON DITCH (3800968)☆: Observed p99 daily rate 55.0 cfs (max 64.6) exceeds total decreed absolute 49.3 cfs across 25208 recorded day(s). Structure holds an Augmentation-use decree -- diversions above the direct-flow decree can be lawful under plan operations; interpret with care.
• LOWLINE DITCH (3800840)☆: Observed p99 daily rate 54.4 cfs (max 61.3) exceeds total decreed absolute 40.5 cfs across 23523 recorded day(s).

Seniority (top structures by decreed rate)

Structure	Senior priority date	Rights	Decreed abs (cfs)	Decreed abs (AF)	Conditional?
FRY ARK PR BOUSTEAD TUNNEL (3804625)☆	1957-07-29	2	1000.0	0	—
ASPEN WHITEWATER COURSE (3801418)☆	1992-06-12	1	653.0	0	—
IND P TM DVR TUNNEL NO 1 (3804617)☆	1930-08-23	1	625.0	0	—
IND P TM DVR TUNNEL NO 2 (3801763)☆	1930-08-23	2	486.2	0	yes
RUEDI RESERVOIR PWR PL (3801360)☆	1975-10-22	1	300.0	0	—
MIN FLOW ROARING FORK 5 (3802112)☆	1985-11-08	1	220.0	0	—
IND P TM DVR N YORK HGT3 (3801766)☆	1930-08-23	3	210.0	0	yes
MIN FLOW FRYINGPAN R MID (3802020)☆	1973-07-12	1	200.0	0	—
MIDLAND FLUME DITCH (3800869)☆	1885-11-16	2	160.0	0	—
MIN FLOW FRYINGPAN R LOW (3802077)☆	1973-07-12	1	110.0	0	—
MIN FLOW CRYSTAL RIVER LOWER (3802114)☆	1975-05-01	1	100.0	0	—
MIN FLOW ROARING FORK 4 (3802111)☆	1985-11-08	1	85.0	0	—
MIN FLOW CRYSTAL R L MID (3802115)☆	1975-05-01	1	80.0	0	—
IND P TM DVR N YORK HGT1 (3801764)☆	1930-08-23	3	76.6	0	—
SWEET JESSUP CANAL (3801038)☆	1902-01-14	4	75.0	0	yes

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.