Arkansas: Las Animas to Stateline

Division 2 · Water District 67

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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.

Reconstruct conditions as of

Evolution of the network

Gage flow trend & changepoints

What counts as a trend here

Computed 2026-08-20 08:42 from 62 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 62 gages with enough record, 10 are trending down and 1 up, and 12 carry a detected shift. The clearest is ARKANSAS RIVER BELOW JOHN MARTIN RESERVOIR, CO., -20.7 points of its long-term median per decade over 89 years (p<0.0001). The other 48 show no clear signal either way.

Gage	Trend	Change / decade points of median	Significance	Years	Changepoint
▸ ARKANSAS RIVER AT GARDEN CITY, KS ARKGARKS	↓ decreasing	-323.6	p=0.000	89	~2001
▸ WILD HORSE CREEK AT HOLLY, CO. WILHOLCO	no clear trend	+253.1	p=0.157	24	~1940
▸ GRANADA IRRIGATION CANAL AUGMENTATION STATION WEST GICAGWCO	↓ decreasing	-187.5	p=0.020	11	~2019
▸ WILD HORSE CREEK ABOVE HOLLY, CO WILDHOCO	↓ decreasing	-179.0	p=0.001	30	~2001
▸ GAGEBY CREEK BELOW FORT LYON CANAL GACBFLCO	↓ decreasing	-175.7	p=0.002	21	~2017
▸ HYDE DITCH HYDDITCO	↑ increasing	+156.5	p=0.029	17	—
▸ FORT LYON CANAL NEAR HASTY, CO. FLYHASCO	↓ decreasing	-68.1	p=0.049	10	—
▸ ARKANSAS RIVER NEAR GRANADA, CO. ARKGRACO	↓ decreasing	-35.7	p=0.006	46	~2001
▸ LAMAR CANAL LAMCANCO	↓ decreasing	-26.7	p=0.010	40	~2001
▸ ARKANSAS RIVER AT LAMAR, CO. ARKLAMCO	↓ decreasing	-22.2	p=0.000	111	~2000
▸ ARKANSAS RIVER BELOW JOHN MARTIN RESERVOIR, CO. ARKJMRCO	↓ decreasing	-20.7	p=0.000	89	~2000
▸ ARKANSAS RIVER AT SYRACUSE, KS ARKSYRKS	↓ decreasing	-15.5	p=0.000	110	~1970
▸ HOLLY DRAIN NEAR HOLLY, CO. HOLHOLCO	no clear trend	+10.0	p=0.156	27	~1941
▸ ARKANSAS RIVER NEAR COOLIDGE, KS ARKCOOKS	no clear trend	-8.0	p=0.050	76	~2001

48 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. 49 gage(s) and 82 structure(s) report in 2026, but structure reporting only reached half its modern level around ~2017. 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	6	0
1930s	6	0
1940s	10	10
1950s	5	12
1960s	5	11
1970s	6	18
1980s	6	8
1990s	12	12
2000s	16	10
2010s	24	44
2020s	48	79

Mass-balance (network closure) trend

Structure divrec-history backfill coverage as of the last check: 2% of 2850 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 (2123 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.

FORT BENT DITCH: reach shifted from -468 cfs to +43 cfs summer mean (more gaining, p=0.003, 19 yr) [sedimentary plains/foothills: moderate groundwater connectivity -- gain/loss shifts can be real aquifer response; corroborate with nearby well records] [16 alluvial wells within 2 mi of the gage; pooled water table -0.7 ft (1961–2023, no_trend)]
GRANADA IRRIGATION CANAL AUGMENTATION STATION EAST: reach shifted from -223 cfs to -187 cfs summer mean (more gaining, p=0.020, 11 yr) [sedimentary plains/foothills: 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=0.61) -- part of it may be unaccounted water becoming accounted, not hydrologic change] [31 alluvial wells within 2 mi of the gage; pooled water table +619.3 ft (1955–2023, decreasing)]
AMITY CANAL: reach shifted from -370 cfs to +243 cfs summer mean (more gaining, p=0.000, 39 yr) [sedimentary plains/foothills: 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=0.78) -- part of it may be unaccounted water becoming accounted, not hydrologic change] [28 alluvial wells within 2 mi of the gage; pooled water table +140256.0 ft (1955–2018, decreasing)]
WILD HORSE CREEK ABOVE HOLLY, CO: reach shifted from -400 cfs to -21 cfs summer mean (more gaining, p=0.000, 25 yr) [sedimentary plains/foothills: 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=0.61) -- part of it may be unaccounted water becoming accounted, not hydrologic change] [31 alluvial wells within 2 mi of the gage; pooled water table +0.9 ft (1955–2023, no_trend)]
KICKING BIRD CANAL: reach shifted from -9 cfs to -9 cfs summer mean (more gaining, p=0.012, 10 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=0.44) -- part of it may be unaccounted water becoming accounted, not hydrologic change]
HYDE DITCH: reach shifted from -180 cfs to -25 cfs summer mean (more gaining, p=0.000, 17 yr) [sedimentary plains/foothills: moderate groundwater connectivity -- gain/loss shifts can be real aquifer response; corroborate with nearby well records] [36 alluvial wells within 2 mi of the gage; pooled water table +47319.1 ft (1956–2018, decreasing)]

Groundwater now has its own tab: 2601 monitored well(s), water-table trends, stream corridors, and the advisory depletion screen.

Reservoirs now has its own tab: 22 reservoir(s), end-of-year storage back to 1949, click-to-chart histories.

Cross-gage pattern fingerprint

Over the 76-year window with full coverage (1951–2026), the dominant shared pattern across 3 gage(s) explains 83% 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.

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.

LAMAR PP OUTFALL (return): +24.7 cfs (100% of that reach's correction)

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	2% of schematic structures have data

Independent check: PASS — 100.0000% agreement across 22,510 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 — 99.85% day-level agreement with USGS's own published records for the same gages, across 19 co-listed station(s) and 272,353 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.

62 gage(s) / 463,423 daily values (1902-08-21–2026-07-06); 234 structure(s) with diversion records; 2116 with decreed rights. Methodology has not yet had independent expert review — treat every figure as an advisory screen, not an administrative or legal conclusion.

25,500 water-level measurements across 2601 monitored well(s) — 1104 alluvial, 887 bedrock — plus 2 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 397 well(s) with enough record for a trend test: 143 declining, 50 rising.

Fastest-declining wells	Setting	ft / decade	Span
▸ SHP-45 TWN.OF SPRINGFIELD	bedrock	-41.99	61 yr
▸ SC02304305CAC2	unknown	-36.26	15 yr
▸ SHP-11 AUSMUS,G,& S. 1	bedrock	-31.58	61 yr
▸ SHP-30 HUME, CHARLES	bedrock	-28.79	88 yr
▸ SHP-09 COGBURN, B.	bedrock	-26.5	42 yr
▸ SHP-18 COMMERCE RANCH 3	bedrock	-26.22	75 yr
▸ SC03004513CCC	bedrock	-25.82	20 yr
▸ SHP-06 MEYERS, S.	bedrock	-24.5	41 yr

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.

FORT BENT DITCH: 16 alluvial well(s) nearby; pooled water table -0.7 ft (1961–2023, no_trend, p=0.2761)

GRANADA IRRIGATION CANAL AUGMENTATION STATION EAST: 31 alluvial well(s) nearby; pooled water table +619.3 ft (1955–2023, decreasing, p=0.0)

AMITY CANAL: 28 alluvial well(s) nearby; pooled water table +140256.0 ft (1955–2018, decreasing, p=0.0)

WILD HORSE CREEK ABOVE HOLLY, CO: 31 alluvial well(s) nearby; pooled water table +0.9 ft (1955–2023, no_trend, p=0.94)

KICKING BIRD CANAL: 0 alluvial well(s) nearby

HYDE DITCH: 36 alluvial well(s) nearby; pooled water table +47319.1 ft (1956–2018, decreasing, p=0.0)

ARKANSAS RIVER AT LAMAR, CO.: 61 alluvial well(s) nearby; pooled water table +0.7 ft (1955–2018, no_trend, p=0.2289)

LAMAR CANAL: 65 alluvial well(s) nearby; pooled water table +0.7 ft (1955–2018, no_trend, p=0.8445)

FORT BENT DITCH AUG STATION: 25 alluvial well(s) nearby; pooled water table +95038.7 ft (1955–2018, decreasing, p=0.0)

BIG SANDY CREEK NEAR LAMAR, CO.: 29 alluvial well(s) nearby; pooled water table +0.0 ft (1956–2023, no_trend, p=0.6867)

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.

22 reservoir(s) with 5,916 storage measurement(s), 1949–2026. Basin storage as of 2025-10-31 (the record's own end — reservoir records publish ~annually): 1,464 AF across 5 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
▸ NEENOSHE RESERVOIR (6703883)	26,000	2007-10-23
▸ JOHN MARTIN RESERVOIR (6703512)	16,152	2012-10-31
▸ GP RANCHES WEST FARM GRAVEL PIT (6706650)	1,413	2025-10-31
▸ WM D PURSE RES NO 1 (6703596)	200	2010-02-23
▸ MUDDY CREEK RESERVOIR (6703597)	149	1963-07-01
▸ DINGWALL REGULATING RESERVOIR (6703536)	116	2010-10-26
▸ L G KINNEY RESERVOIR (6703540)	40	2025-10-31
▸ R R RUTHERFORD RESERVOIR (6703600)	25	2010-02-23

Decreed rights on this network run from 1871-03-13 to 2018-10-30. 7 abandonment screens and 23 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: 2337 across 2116 structure(s); 186 structure(s) carry 0 court-case references. Advisory reading aids on public DWR data — not administrative or legal conclusions.

Abandonment radar (7 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 ~2017 — idleness that begins before then may be unreported use, not nonuse (flagged † below).

GRAHAM DITCH (6700572) (1891-08-24, 61.0 cfs decreed): last active 1963 — 46 years idle † predates modern reporting era — last recorded activity predates this basin's modern reporting era (~2017) -- early absence of record is weak evidence of nonuse
CLINGINGSMITH OUTLET DITCH (6700513) (1954-07-31, 3.0 cfs decreed): last active 1970 — 39 years idle † predates modern reporting era — last recorded activity predates this basin's modern reporting era (~2017) -- early absence of record is weak evidence of nonuse
AMITY CANAL (BIG SANDY) (6700672) (1893-04-01, 510.0 cfs decreed): last active 1971 — 38 years idle † predates modern reporting era — last recorded activity predates this basin's modern reporting era (~2017) -- early absence of record is weak evidence of nonuse
R M RAY SEEP DITCH NO 1 (6700506) (1920-09-26, 2.8 cfs decreed): last active 1972 — 37 years idle † predates modern reporting era — last recorded activity predates this basin's modern reporting era (~2017) -- early absence of record is weak evidence of nonuse
NOWELS PIPELINE (6700594) (1920-08-10, 4.0 cfs decreed): last active 1972 — 37 years idle † predates modern reporting era — last recorded activity predates this basin's modern reporting era (~2017) -- early absence of record is weak evidence of nonuse
E R JONES SEEPAGE DITCH (6700644) (1920-09-26, 2.2 cfs decreed): last active 1972 — 37 years idle † predates modern reporting era — last recorded activity predates this basin's modern reporting era (~2017) -- early absence of record is weak evidence of nonuse
REYHER WELL NO 8 (6705011) (1965-03-15, 1.5 cfs decreed): last active 1973 — 36 years idle † predates modern reporting era — last recorded activity predates this basin's modern reporting era (~2017) -- early absence of record is weak evidence of nonuse

Compliance screens (23 advisory flags)

Screened 74 of 2116 structures with rights (85 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.

JOHN MARTIN RESERVOIR (6703512): Observed p99 daily rate 1062.8 cfs (max 6030.2) exceeds total decreed absolute 63.0 cfs across 33628 recorded day(s). Structure holds an Augmentation-use decree -- diversions above the direct-flow decree can be lawful under plan operations; interpret with care.
BUFFALO CANAL (ARKANSAS) (6700608): Observed p99 daily rate 90.0 cfs (max 171.8) exceeds total decreed absolute 67.5 cfs across 55364 recorded day(s).
THURSTON PIPELINE (6702500): Observed p99 daily rate 55.4 cfs (max 68.4) exceeds total decreed absolute 25.0 cfs across 180 recorded day(s).
IDEAL DITCH (6700555): Observed p99 daily rate 16.1 cfs (max 32.8) exceeds total decreed absolute 10.0 cfs across 4082 recorded day(s).
SISSON & STUBBS DITCH 1 (6700616): Observed p99 daily rate 15.0 cfs (max 25.0) exceeds total decreed absolute 7.0 cfs across 6571 recorded day(s). Structure holds an Augmentation-use decree -- diversions above the direct-flow decree can be lawful under plan operations; interpret with care.
GERALD VERHOEFF DITCH (6700544): Observed p99 daily rate 11.4 cfs (max 564.3) exceeds total decreed absolute 10.0 cfs across 9149 recorded day(s).
CALVIN FLINT DITCH NO 2 (6700559): Observed p99 daily rate 11.1 cfs (max 20.0) exceeds total decreed absolute 10.0 cfs across 4454 recorded day(s).
L G KINNEY DITCH (6700660): Observed p99 daily rate 11.1 cfs (max 11.1) exceeds total decreed absolute 3.0 cfs across 52 recorded day(s).
JAMES CUSHNY DITCH (6700579): Observed p99 daily rate 5.5 cfs (max 16.4) exceeds total decreed absolute 5.3 cfs across 2454 recorded day(s).
WAGNER & GILBERT P/L (6700593): Observed p99 daily rate 5.3 cfs (max 6.5) exceeds total decreed absolute 5.0 cfs across 282 recorded day(s).

Seniority (top structures by decreed rate)

Structure	Senior priority date	Rights	Decreed abs (cfs)	Decreed abs (AF)	Conditional?
AMITY CANAL (6700607)	1887-02-21	3	783.5	0	yes
AMITY CANAL (GOULDS DR) (6700533)	1893-04-01	2	700.0	0	yes
AMITY CANAL (BIG BEND) (6700575)	1893-04-01	2	700.0	0	yes
AMITY CANAL (BIG SANDY) (6700672)	1893-04-01	2	510.0	0	yes
AMITY CANAL (MAY VALLEY) (6700520)	1908-05-26	3	503.6	0	yes
LAMAR CANAL (6700614)	1875-11-30	4	285.8	0	—
FORT BENT CANAL (6700610)	1886-04-01	6	228.5	0	—
BUFFALO CANAL (PUNTNEY) (6700505)	1895-10-01	1	135.0	0	—
BUFFALO CANAL (BUFFALO) (6700557)	1895-10-01	1	135.0	0	—
BUFFALO CANAL (DEADMAN) (6700565)	1895-10-01	1	135.0	0	—
BUFFALO CANAL (HOUSE DR) (6700548)	1895-10-01	1	107.0	0	—
BUFFALO CANAL (SIMPSON) (6700514)	1895-10-01	1	105.0	0	—
X-Y IRRIGATING DITCH (6700617)	1889-07-22	1	69.0	0	—
BUFFALO CANAL (ARKANSAS) (6700608)	1885-01-29	1	67.5	0	—
JOHN MARTIN RESERVOIR (6703512)	1871-03-13	13	63.0	357385	—

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

Administration number

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