Arkansas: Fowler to Las Animas

Source Our computation, no independent reference · computed here from the screened DWR record Source Our computation, no independent reference · no independent reference; see /methods

This year, in context

In the weeks around 2026-09-27 (the newest reading on file), flows at the 29 ranked gages are running at a median 39% of their own long-term norm for this window — 21 below a typical year, 8 at or above. Driest relative to its record: ARF HEADGATE 27 (BENTS FORT), ranking 1st lowest of 10 years.

Gage flow trend & changepoints

Of the 57 gages with enough record, 11 are trending down and 1 up, and 13 carry a detected shift. The clearest is Purgatoire River at Ninemile Dam near Higbee, its annual mean flow changing -7.17 cfs per decade (-12.4% of its median annual flow) over 101 years (p<0.0001). The other 41 show no clear signal either way.

Drought history, cost, and the four-century context moved to the Drought tab.

⚠️ 2 gages flagged: their records may have quietly shifted against their neighbours, so treat their trends with caution.

41 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. 43 gage(s) and 49 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 †.

Mass-balance (network closure) trend

Structure divrec-history backfill coverage as of the last check: 1% of 3833 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 (4051 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.

• ARKANSAS RIVER AT LA JUNTA, CO: reach shifted from +302 cfs to -135 cfs summer mean (more losing, p=0.000, 77 yr) [sedimentary plains/foothills: moderate groundwater connectivity -- gain/loss shifts can be real aquifer response; corroborate with nearby well records] [74 alluvial wells within 2 mi of the gage; pooled water table +2.3 ft (1959–2018, increasing)]
• ARKANSAS RIVER AT LAS ANIMAS, CO.: reach shifted from -93 cfs to +329 cfs summer mean (more gaining, p=0.002, 77 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=0.51) -- part of it may be unaccounted water becoming accounted, not hydrologic change] [43 alluvial wells within 2 mi of the gage; pooled water table +0.3 ft (1955–2023, no_trend)]
• TIMPAS CREEK AT MOUTH NEAR SWINK, CO.: reach shifted from -270 cfs to +82 cfs summer mean (more gaining, p=0.000, 58 yr) [alluvial valley: real alluvial aquifer -- a decades-long shift toward losing is the classic signature of alluvial pumping and urbanization] [33 alluvial wells within 2 mi of the gage; pooled water table +2549.3 ft (1959–2023, no_trend)]
• HOLBROOK CANAL AT MILE 3.4 NEAR ROCKY FORD: reach shifted from -7 cfs to +125 cfs summer mean (more gaining, p=0.010, 41 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=0.44) -- part of it may be unaccounted water becoming accounted, not hydrologic change] [19 alluvial wells within 2 mi of the gage; pooled water table -0.3 ft (1960–2011, decreasing)]
• PURGATOIRE RIVER NEAR LAS ANIMAS, CO.: reach shifted from -43 cfs to -255 cfs summer mean (more losing, p=0.001, 77 yr) [alluvial valley: real alluvial aquifer -- a decades-long shift toward losing is the classic signature of alluvial pumping and urbanization] [17 alluvial wells within 2 mi of the gage; pooled water table +1585.6 ft (1959–2023, no_trend)]
• HORSE CREEK AT HIGHWAY 194: reach shifted from -114 cfs to +23 cfs summer mean (more gaining, p=0.000, 34 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=0.6) -- part of it may be unaccounted water becoming accounted, not hydrologic change] [21 alluvial wells within 2 mi of the gage; pooled water table +95267.5 ft (1958–2018, increasing)]

Groundwater now has its own tab: 1087 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 1950, click-to-chart histories.

Cross-gage pattern fingerprint

Over the 88-year window with full coverage (1939–2026), the dominant shared pattern across 4 gage(s) explains 84% 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 2026-09-27)

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.

• CLUTE SPRING DITCH (diversion): +1.3 cfs (4% of that reach's correction)
• 1714550 (diversion): +1.3 cfs (4% of that reach's correction)
• PITZER POND (diversion): +1.3 cfs (4% of that reach's correction)
• PITZER POND (diversion): +1.3 cfs (4% of that reach's correction)
• 1714387 (diversion): +1.3 cfs (4% of that reach's correction)
• PEARCE SPRING (return): +1.3 cfs (4% of that reach's correction)
• 1714308 (diversion): +1.3 cfs (4% of that reach's correction)
• 1713339 (diversion): +1.3 cfs (4% of that reach's correction)
• 1713340 (diversion): +1.3 cfs (4% of that reach's correction)
• ROCKY FORD HL AG ST @ PONDS (diversion): +1.3 cfs (4% of that reach's correction)

Source DWR administrative record · verify at DWR groundwater wells ↗ Source DWR administrative record · verify at DWR well permits ↗

21,337 water-level measurements across 1087 monitored well(s) — 917 alluvial, 29 bedrock — plus 5 administered well(s) reporting metered pumping.

Well map

3D aquifer x-ray

Every aquifer unit as its own head surface, animated through time.

Water-table trends

Of 287 well(s) with enough record for a trend test: 52 declining, 65 rising.

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.

ARKANSAS RIVER AT LA JUNTA, CO: 74 alluvial well(s) nearby; pooled water table +2.3 ft (1959–2018, increasing, p=0.0286). 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).

ARKANSAS RIVER AT LAS ANIMAS, CO.: 43 alluvial well(s) nearby; pooled water table +0.3 ft (1955–2023, no_trend, p=0.0527). 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).

TIMPAS CREEK AT MOUTH NEAR SWINK, CO.: 33 alluvial well(s) nearby; pooled water table +2549.3 ft (1959–2023, no_trend, p=0.7467)

HOLBROOK CANAL AT MILE 3.4 NEAR ROCKY FORD: 19 alluvial well(s) nearby; pooled water table -0.3 ft (1960–2011, decreasing, p=0.0029)

PURGATOIRE RIVER NEAR LAS ANIMAS, CO.: 17 alluvial well(s) nearby; pooled water table +1585.6 ft (1959–2023, no_trend, p=0.8575)

HORSE CREEK AT HIGHWAY 194: 21 alluvial well(s) nearby; pooled water table +95267.5 ft (1958–2018, increasing, p=0.0063)

APISHAPA RIVER NEAR FOWLER, CO: 47 alluvial well(s) nearby; pooled water table +0.1 ft (1959–2023, no_trend, p=0.8327)

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.

Source DWR administrative record · verify at DWR structure records ↗

22 reservoir(s) with 10,582 storage measurement(s), 1950–2024.

Reservoir map — how full is each vessel?

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 row to chart its full storage history, or open its dossier for rights, documents and dam-safety facts.

Source Our computation, no independent reference · computed here from the screened DWR record Source Independent agency measurement · fetched 2026-10-06 · verify at U.S. Drought Monitor ↗

Right now

This is the 55th-driest week 39 in 115 years of record at ARKANSAS RIVER AT LA JUNTA, CO (as of 2026-09-21; this week’s flow sits at the 48th percentileRank against the record: a river at its 5th percentile is lower than it was in 95 of the past 100 years on this same date. for the date). On this week’s US Drought Monitor, Las Animas County is 8% in D3 extreme drought (2026-10-06). The law agrees: the most senior active call leaves 97% of this district’s decreed flow rights junior to the calling right this week.

Every year since 1912, week by week

Each thin row is a year at ARKANSAS RIVER AT LA JUNTA, CO; each cell is one week’s flow ranked against the same calendar week of every other year — warm means dry for the date, blue wet, so seasonality cancels and droughts appear as warm bands. Gaps are missing record, never a dry river. Click a year to reconstruct it on the Historical tab.

This year against its analogs

Over the 39 weeks recorded so far, 2026’s weekly trace most resembles 2002 (mean gap 13.7 percentile points; next closest 2012 (16.6), 2018 (17.9)). The analog’s remainder is drawn as context — its ending is what happened to it, not a forecast for this year.

The Drought Monitor’s view since 2000

Mean share of area in each class across Bent, Crowley, Kiowa, Las Animas, Lincoln, Otero, Otero, Pueblo counties — the counties this district’s gages sit in, which overlap the district imperfectly. The Drought Monitor weighs soils, vegetation and local reports; it is CONTEXT beside the river’s own record above, not the water-rights picture.

The law’s own drought gauge

When water runs short, administration answers: calls reach further back in time, and more decreed rights go junior to the calling right. This is that response, weekly since 2005 — the share of this district’s decreed flow rights junior to the most senior active call. Watch it spike in the named droughts below, and linger after the river recovers.

Computed from DWR’s call record (838 calls touching this district) against the district’s rights index. Scoping is deliberately coarse — a call’s own district, or districts named in its comments — and this is administration’s RESPONSE, not a per-structure verdict (each dossier’s curtailment card does that, with stream miles). A deepening call can also reflect growing demand, not only shrinking supply.

This basin’s droughts, by its own record

Detected mechanically: the 26-week smoothed percentile below the 30th for at least 20 weeks; recovered on regaining the 50th. The water-table clock compares each monitoring well against its own pre-drought median (the 3 years before onset) and dates the year the median well got back — the aquifer remembers longest, and “still below” is a finding, not a gap. The knobs are stated because the episode list depends on them — a different reasonable choice merges or splits episodes at the edges. Names are attached where an episode overlaps a drought Colorado already talks about.

What drought has cost here

Since 1991, federal crop insurance has paid $289,232,309 in drought-caused claims across Bent, Crowley, Kiowa, Las Animas, Lincoln, Otero, Pueblo counties — 39.4% of all insured crop losses there. The worst year was 2013 ($43,072,721).

USDA crop-insurance indemnities where the recorded cause of loss is drought, summed over the counties this district's gages sit in. Counties overlap water districts imperfectly, and insured-crop claims are a floor on drought damage, not a total. Source: USDA RMA cause-of-loss files.

When this basin claimed its water

Every bar is a year’s new appropriations (1,873 rights across 115 years of shared record), colored by that year’s wetness from the barcode above. Here the correlation is -0.43 — this basin tended to claim water in dry times, under scarcity pressure. Across the state both behaviors exist: ephemeral southwest basins file after wet demonstrations, transbasin-source basins under drought — and the biggest statewide filing waves sat in the 1950s drought and after 2002, not in the wet 1980s–90s.

Appropriation dates are the CLAIMED initiation of a right, not the courthouse filing date; the record is survivor-biased (abandoned claims are absent, so failed dry-era scrambles are undercounted); and the big 1960s and 2000s spikes sit on legal events — the pre-1969-Act adjudication era and 2000s legislation — not on weather. A correlation here is a description, never a cause.

New to how a dry winter becomes a call on the river? Anatomy of a drought walks the chain in four minutes — snow to rivers to reservoirs to calls to the water table.

Who serves it, who protects it

Two registers the site fetches on their own schedules, read for this district. Neither is a DWR record; each links its own page and its agency.

Public water systems here

Source Register of another agency · fetched 2026-10-06 · verify at EPA SDWIS ↗

19 systems touch this district (19 community systems reporting 21,381 people served, a figure that counts a wholesaler's customers twice); 4 of them carry an open health-based violation on EPA's record.

and 11 more; the full directory filters by district.

Instream-flow rights held by the state

Source Register of another agency · fetched 2026-10-11 · verify at CWCB instream flow program ↗

The Board's tabulation lists no instream-flow reach or natural lake level in this district. Statewide →

What the water is like -- USGS sensors right now, where it has been sampled, the impaired-waters list, and how the tap water here stands with EPA -- is on the Water quality tab.

Designated groundwater basins are on their own page.

Source Adjudicated record · verify at DWR water-right transactions ↗ Source Adjudicated record · verify at DWR net amounts ↗

Decreed rights on this network run from 1861-12-31 to 2022-09-21. Of the 20 structures with a yield estimate, the median one’s senior right was in priority 0% of a median irrigation season and 0% in a dry one. 20 abandonment screens and 19 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: 2077 across 1909 structure(s); 97 structure(s) carry 0 court-case references. Advisory reading aids on public DWR data — not administrative or legal conclusions.

Is the river getting harder to divert from?

Over 2003–2025, administration on this district has been tightening: 3 of 3 measures (days under callA senior water right demanding its water, which requires everyone junior on that stream to stop diverting until it is satisfied., calls set, seniorityColorado shares water by date: the earlier the right, the stronger its claim when the river runs short. "First in time, first in right." of the controlling call) are moving toward more administration, none the other way.

Why diversions stopped — call-based explanations

Sustained diversion stops matched to senior administrative calls.

• A J ANDERSON DITCH (1700577) DWR↗☆ stopped 2025-10-19 (12+ days) — call at CHILILI DITCH curtailing 100% of its decreed rate [heuristic-strong]
• 1700540 DWR↗☆ stopped 2025-08-22 (25+ days) — call at MODEL DITCH curtailing 100% of its decreed rate [heuristic-strong]
• A J ANDERSON DITCH (1700577) DWR↗☆ stopped 2025-08-08 (13+ days) — call at HARDSCRABBLE DITCH curtailing 100% of its decreed rate [heuristic-strong]
• HOLBROOK CANAL (1700554) DWR↗☆ stopped 2025-08-07 (19+ days) — call at HARDSCRABBLE DITCH curtailing 100% of its decreed rate [heuristic-strong]
• 1700540 DWR↗☆ stopped 2025-07-21 (17+ days) — call at MODEL DITCH curtailing 100% of its decreed rate [heuristic-strong]
• NINE MILE CANAL (1700604) DWR↗☆ stopped 2025-07-05 (51+ days) — call at MODEL DITCH curtailing 100% of its decreed rate [heuristic-strong]
• 1700540 DWR↗☆ stopped 2025-06-17 (24+ days) — call at PULASKI DITCH curtailing 100% of its decreed rate [heuristic-strong]
• DEADMAN GULCH DITCH NO 4 (1700580) DWR↗☆ stopped 2025-06-13 (42+ days) — call at LUCERO DITCH curtailing 100% of its decreed rate [heuristic-strong]
• A J ANDERSON DITCH (1700577) DWR↗☆ stopped 2025-05-22 (20+ days) — call at HOEHNE DITCH curtailing 100% of its decreed rate [heuristic-strong]
• CANADY DITCH (1700587) DWR↗☆ stopped 2025-05-06 (26+ days) — call at LUCERO DITCH curtailing 100% of its decreed rate [heuristic-strong]
• NINE MILE CANAL (1700604) DWR↗☆ stopped 2025-03-31 (37+ days) — call at SPANISH PEAKS DITCH curtailing 100% of its decreed rate [heuristic-strong]
• 1700540 DWR↗☆ stopped 2025-03-13 (14+ days) — call at TITSWORTH DITCH curtailing 100% of its decreed rate [heuristic-strong]

Right yield — how often could these rights actually divert?

Share of irrigation-season days each structure's rights were not called out, derived from the 22-year district-scoped call record (senior right = floor, junior right = ceiling constraint). Call-record-derived; DWR's own analysis governs where available.

Abandonment radar (20 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).

• CLUTE SPRING DITCH (1700627) DWR↗☆ (1948-07-31, 1.0 cfs decreed): last active 1980 — 45 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
• FOULK DITCH & IRRIG SYS (1700564) DWR↗☆ (1954-01-01, 3.0 cfs decreed): last active 1982 — 43 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
• 1700575 DWR↗☆ (1948-12-02, 5.0 cfs decreed): last active 1983 — 42 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
• CROWLEY COUNTY WELL NO 3 (1706019) DWR↗☆ (1981-08-31, 0.6 cfs decreed): last active 1983 — 42 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
• ADOBE CREEK FEEDER (1700674) DWR↗☆ (1906-01-25, 17262.0 cfs decreed): last active 2007 — 18 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
• MUSTANG RESERVOIR CANAL (1700608) DWR↗☆ (1902-03-17, 5.0 cfs decreed): last active 2009 — 16 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
• MCCABE DITCH NO 1 (1700660) DWR↗☆ (1905-09-09, 10.0 cfs decreed): last active 2010 — 15 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
• MCCABE DITCH NO 2 (1700688) DWR↗☆ (1905-09-09, 10.0 cfs decreed): last active 2010 — 15 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
• DOUGLAS - GORDON RES (1703912) DWR↗☆ (1919-04-16, 0.0 cfs decreed): last active 2010 — 15 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
• DAWN POND (1703508) DWR↗☆ (1964-10-22, 0.0 cfs decreed): last active 2011 — 14 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 (19 advisory flags)

Screened 59 of 1909 structures with rights (71 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.

• CROOKED ARROYA DITCH (1700578) DWR↗☆: Observed p99 daily rate 1710.0 cfs (max 1710.0) exceeds total decreed absolute 27.2 cfs across 12241 recorded day(s).
• BEST DITCH HEADGATE 1 (1700605) DWR↗☆: Observed p99 daily rate 301.3 cfs (max 325.0) exceeds total decreed absolute 50.0 cfs across 196 recorded day(s).
• BEER DITCH (1700561) DWR↗☆: Observed p99 daily rate 230.0 cfs (max 230.0) exceeds total decreed absolute 100.0 cfs across 166 recorded day(s).
• HORSE CREEK & BLACK DRAW DITCH (1700592) DWR↗☆: Observed p99 daily rate 225.0 cfs (max 255.0) exceeds total decreed absolute 190.5 cfs across 180 recorded day(s).
• MUSTANG RESERVOIR CANAL (1700608) DWR↗☆: Observed p99 daily rate 151.2 cfs (max 152.0) exceeds total decreed absolute 5.0 cfs across 218 recorded day(s).
• LAS ANIMAS CONSOLIDATED (1700556) DWR↗☆: Observed p99 daily rate 131.3 cfs (max 190.0) exceeds total decreed absolute 94.6 cfs across 70259 recorded day(s).
• 1700541 DWR↗☆: Observed p99 daily rate 131.0 cfs (max 442.0) exceeds total decreed absolute 129.4 cfs across 74187 recorded day(s).
• ROCKY FORD DITCH (1700558) DWR↗☆: Observed p99 daily rate 120.0 cfs (max 631.0) exceeds total decreed absolute 116.2 cfs across 81054 recorded day(s).
• MCCABE DITCH NO 1 (1700660) DWR↗☆: Observed p99 daily rate 90.0 cfs (max 90.0) exceeds total decreed absolute 10.0 cfs across 60 recorded day(s).
• CROWLEY COUNTY WELL NO 3 (1706019) DWR↗☆: Observed p99 daily rate 37.2 cfs (max 37.2) exceeds total decreed absolute 0.6 cfs across 46 recorded day(s).

Seniority (top structures by decreed rate)

Recent inventory & legal-document changes

• 2026-10-10 — call set: FORT LYON CANAL (39703)
• 2026-10-10 — call set: JOHN MARTIN RESERVOIR (39705)
• 2026-10-10 — call released: 39701
• 2026-10-10 — call released: 39694
• 2026-10-09 — call set: FORT LYON CANAL (39701)
• 2026-10-09 — call released: 39660
• 2026-10-09 — call released: 39675
• 2026-10-09 — call released: 39659

Water-court filings this month (division-wide)

3 applications in the 2026-08 resume for this basin's division — new rights, changes, augmentation plans — from the water clerk's statutory monthly notice (C.R.S. 37-92-302), the earliest public signal of a new claim. Filings are division-wide, not district-filtered: check the county column. Full resume PDF at the Judicial Branch →

Anyone affected may file a statement of opposition until 2026-10-31 (19 days left). C.R.S. 37-92-302(3): due by the last day of the second month following the filing month — computed, not legal advice; confirm with the water clerk.

Active substitute water supply plans in this district

Temporary State Engineer approvals to divert out of priority (37-92-308 / 37-90-137). A structure operating under one behaves differently under a call than its decreed rights alone suggest — the priority tables above don't know about these; this list does. Source: DWR’s active-SWSP register, refreshed nightly.