South Platte: Greeley to Balzac

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 28 ranked gages are running at a median 43% of their own long-term norm for this window — 22 below a typical year, 6 at or above. Driest relative to its record: NEW CACHE LOWER SAND CREEK RETURN, ranking 1st lowest of 7 years.

Gage flow trend & changepoints

Of the 51 gages with enough record, 3 are trending down and 2 up, and 3 carry a detected shift. The clearest is Fort Morgan Canal near Wiggins, its annual mean flow changing -9.42 cfs per decade (-9.3% of its median annual flow) over 32 years (p=0.0010). The other 46 show no clear signal either way.

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

46 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. 37 gage(s) and 459 structure(s) report in 2026, but structure reporting only reached half its modern level around ~2009. 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: 5% of 6818 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 (2347 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.

• ILLINOIS DITCH: reach shifted from -1474 cfs to -513 cfs summer mean (more gaining, p=0.008, 16 yr) [alluvial valley: real alluvial aquifer -- a decades-long shift toward losing is the classic signature of alluvial pumping and urbanization] [19 alluvial wells within 2 mi of the gage; pooled water table +0.1 ft (1966–2026, no_trend)]
• SOUTH PLATTE RIVER NEAR WELDONA, CO: reach shifted from -247 cfs to +530 cfs summer mean (more gaining, p=0.000, 74 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=0.74) -- part of it may be unaccounted water becoming accounted, not hydrologic change] [28 alluvial wells within 2 mi of the gage; pooled water table -3.3 ft (1949–2025, no_trend)]
• SOUTH PLATTE RIVER AT FORT MORGAN, CO: reach shifted from -98 cfs to +620 cfs summer mean (more gaining, p=0.000, 39 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=0.73) -- part of it may be unaccounted water becoming accounted, not hydrologic change] [17 alluvial wells within 2 mi of the gage; pooled water table +0.8 ft (1962–2025, no_trend)]
• SOUTH PLATTE RIVER AT COOPER BRIDGE NEAR BALZAC: reach shifted from -455 cfs to +153 cfs summer mean (more gaining, p=0.046, 39 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=0.54) -- part of it may be unaccounted water becoming accounted, not hydrologic change] [26 alluvial wells within 2 mi of the gage; pooled water table +0.2 ft (1966–2025, no_trend)]
• FORT MORGAN CANAL NEAR WIGGINS, CO: reach shifted from -16 cfs to +73 cfs summer mean (more gaining, p=0.020, 35 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=0.68) -- part of it may be unaccounted water becoming accounted, not hydrologic change] [20 alluvial wells within 2 mi of the gage; pooled water table +0.2 ft (1966–2025, increasing)]
• SOUTH PLATTE RIVER AT MASTERS, CO.: reach shifted from -425 cfs to -63 cfs summer mean (more gaining, p=0.019, 28 yr) [alluvial valley: real alluvial aquifer -- a decades-long shift toward losing is the classic signature of alluvial pumping and urbanization] [26 alluvial wells within 2 mi of the gage; pooled water table +1.6 ft (1947–2025, no_trend)]

Groundwater now has its own tab: 6824 monitored well(s), water-table trends, stream corridors, and the advisory depletion screen.

Reservoirs now has its own tab: 38 reservoir(s), end-of-year storage back to 1950, click-to-chart histories.

Cross-gage pattern fingerprint

Over the 39-year window with full coverage (1988–2026), the dominant shared pattern across 3 gage(s) explains 97% 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.

• BROWN PYOTT DITCH (diversion): +3.9 cfs (3% of that reach's correction)
• PEIF PIPELINE (diversion): +3.9 cfs (3% of that reach's correction)
• DUPE WDID, SEE 0100523 (diversion): +3.9 cfs (3% of that reach's correction)
• LITCH SEEP DITCH (diversion): +3.9 cfs (3% of that reach's correction)
• PAWNEE RAW WTR RES 1 (diversion): +3.9 cfs (3% of that reach's correction)
• PAWNEE RAW WTR RES 2 (diversion): +3.9 cfs (3% of that reach's correction)
• SNYDER DITCH (diversion): +3.9 cfs (3% of that reach's correction)
• TREMONT DITCH (diversion): +3.9 cfs (3% of that reach's correction)
• A A SMITH DITCH (diversion): +3.9 cfs (3% of that reach's correction)
• LOWER PLATTE BEAVER D (diversion): +3.9 cfs (3% of that reach's correction)

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

237,108 water-level measurements across 6824 monitored well(s) — 1967 alluvial, 3490 bedrock — plus 152 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 437 well(s) with enough record for a trend test: 171 declining, 59 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.

ILLINOIS DITCH: 19 alluvial well(s) nearby; pooled water table +0.1 ft (1966–2026, no_trend, p=0.8769). Glover screen: 1.2 cfs of nearby metered alluvial pumping → est. lagged depletion 0.7–1.1 cfs (uncalibrated T/S ranges; flagged for SPDSS calibration, AWAS cross-check, and expert review — DWR's AWAS is the authority).

SOUTH PLATTE RIVER NEAR WELDONA, CO: 28 alluvial well(s) nearby; pooled water table -3.3 ft (1949–2025, no_trend, p=0.6307)

SOUTH PLATTE RIVER AT FORT MORGAN, CO: 17 alluvial well(s) nearby; pooled water table +0.8 ft (1962–2025, no_trend, p=0.1389). Glover screen: 0.8 cfs of nearby metered alluvial pumping → est. lagged depletion 0.6–0.8 cfs (uncalibrated T/S ranges; flagged for SPDSS calibration, AWAS cross-check, and expert review — DWR's AWAS is the authority).

SOUTH PLATTE RIVER AT COOPER BRIDGE NEAR BALZAC: 26 alluvial well(s) nearby; pooled water table +0.2 ft (1966–2025, no_trend, p=0.7125). Glover screen: 2.3 cfs of nearby metered alluvial pumping → est. lagged depletion 1.7–2.2 cfs (uncalibrated T/S ranges; flagged for SPDSS calibration, AWAS cross-check, and expert review — DWR's AWAS is the authority).

FORT MORGAN CANAL NEAR WIGGINS, CO: 20 alluvial well(s) nearby; pooled water table +0.2 ft (1966–2025, increasing, p=0.0139). Glover screen: 1.6 cfs of nearby metered alluvial pumping → est. lagged depletion 1.0–1.5 cfs (uncalibrated T/S ranges; flagged for SPDSS calibration, AWAS cross-check, and expert review — DWR's AWAS is the authority).

SOUTH PLATTE RIVER AT MASTERS, CO.: 26 alluvial well(s) nearby; pooled water table +1.6 ft (1947–2025, no_trend, p=0.507). Glover screen: 3.1 cfs of nearby metered alluvial pumping → est. lagged depletion 2.1–2.9 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.

Source DWR administrative record · verify at DWR structure records ↗

38 reservoir(s) with 68,625 storage measurement(s), 1950–2026. Basin storage as of 2025-10-31 (the record's own end — reservoir records publish ~annually): 35,243 AF across 13 reservoir(s).

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 20th-driest week 39 in 124 years of record at SOUTH PLATTE RIVER NEAR KERSEY, CO (as of 2026-09-21; this week’s flow sits at the 16th 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, Weld County is 7% in D4 exceptional drought (2026-10-06).

Every year since 1901, week by week

Each thin row is a year at SOUTH PLATTE RIVER NEAR KERSEY, 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 1908 (mean gap 11.8 percentile points; next closest 1950 (12.2), 1932 (13.2)). 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 Adams, El Paso, Elbert, Morgan, Washington, Weld 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.

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 $332,268,749 in drought-caused claims across Adams, El Paso, Elbert, Morgan, Washington, Weld counties — 38.3% of all insured crop losses there. The worst year was 2022 ($81,587,616).

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 (8,493 rights across 124 years of shared record), colored by that year’s wetness from the barcode above. Here the correlation is -0.1 — essentially no wet-dry pattern; here, law and settlement set the pace, not the weather. 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 ↗

38 systems touch this district (38 community systems reporting 1,982,790 people served, a figure that counts a wholesaler's customers twice); none carries an open health-based violation on EPA's record.

and 30 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 ↗

2 reaches over 4.9 miles, held by the Colorado Water Conservation Board so that water stays in the stream. Every reach, with its schedule and case →

• Graves Creek, 2.76 mi: 0.17 (1/1 - 12/31) cfs (appropriated 2015, 15CW3157) · dossier
• Lone Tree Creek, 2.17 mi: 0.3 (1/1 - 12/31) cfs (appropriated 2016, 16CW3173) · dossier

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 1860-12-31 to 2024-12-31. 18 abandonment screens and 107 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: 8938 across 7708 structure(s); 1 structure(s) carry 0 court-case references. Advisory reading aids on public DWR data — not administrative or legal conclusions.

Abandonment radar (18 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 ~2009 — idleness that begins before then may be unreported use, not nonuse (flagged † below).

• SNYDER RES (0103342) DWR↗☆ (1902-03-20, 0.0 cfs decreed): last active 1998 — 27 years idle † predates modern reporting era — last recorded activity predates this basin's modern reporting era (~2009) -- early absence of record is weak evidence of nonuse
• SNOW UDA WL FLD (0110051) DWR↗☆ (2004-11-30, 0.0 cfs decreed): last active 2006 — 19 years idle † predates modern reporting era — last recorded activity predates this basin's modern reporting era (~2009) -- early absence of record is weak evidence of nonuse
• MORGAN CTY COMMUNITY C W 1-31867 (0107709) DWR↗☆ (1986-12-29, 0.2 cfs decreed): last active 2007 — 18 years idle † predates modern reporting era — last recorded activity predates this basin's modern reporting era (~2009) -- early absence of record is weak evidence of nonuse
• FT MORGAN WELL 47070-F (0109965) DWR↗☆ (2005-01-01, 0.3 cfs decreed): last active 2007 — 18 years idle † predates modern reporting era — last recorded activity predates this basin's modern reporting era (~2009) -- early absence of record is weak evidence of nonuse
• FT MORGAN WELL 56253 (0109976) DWR↗☆ (2005-01-01, 1.6 cfs decreed): last active 2007 — 18 years idle † predates modern reporting era — last recorded activity predates this basin's modern reporting era (~2009) -- early absence of record is weak evidence of nonuse
• FT MORGAN WELL 57064 (0109977) DWR↗☆ (2005-01-01, 0.3 cfs decreed): last active 2007 — 18 years idle † predates modern reporting era — last recorded activity predates this basin's modern reporting era (~2009) -- early absence of record is weak evidence of nonuse
• FT MORGAN WELL 59870 (0109978) DWR↗☆ (2005-01-01, 0.1 cfs decreed): last active 2007 — 18 years idle † predates modern reporting era — last recorded activity predates this basin's modern reporting era (~2009) -- early absence of record is weak evidence of nonuse
• FT MORGAN WELL 59871 (0109979) DWR↗☆ (2005-01-01, 0.5 cfs decreed): last active 2007 — 18 years idle † predates modern reporting era — last recorded activity predates this basin's modern reporting era (~2009) -- early absence of record is weak evidence of nonuse
• FT MORGAN WELL 59872 (0109980) DWR↗☆ (2005-01-01, 0.3 cfs decreed): last active 2007 — 18 years idle † predates modern reporting era — last recorded activity predates this basin's modern reporting era (~2009) -- early absence of record is weak evidence of nonuse
• FT MORGAN WELL 59873 (0109981) DWR↗☆ (2005-01-01, 0.5 cfs decreed): last active 2007 — 18 years idle † predates modern reporting era — last recorded activity predates this basin's modern reporting era (~2009) -- early absence of record is weak evidence of nonuse

Compliance screens (107 advisory flags)

Screened 170 of 7708 structures with rights (250 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.

• CENTRAL AUG HEADGATE WELL GROUP (0104803) DWR↗☆: Observed p99 daily rate 32.0 cfs (max 95.9) exceeds total decreed absolute 23.4 cfs across 2215 recorded day(s).
• TH 17 RANCH RIVER RESERVOIR PUMP (0100913) DWR↗☆: Observed p99 daily rate 28.2 cfs (max 29.3) exceeds total decreed absolute 4.2 cfs across 2078 recorded day(s).
• BOXELDER FLD WTR D 2 (0100616) DWR↗☆: Observed p99 daily rate 26.0 cfs (max 211.0) exceeds total decreed absolute 21.0 cfs across 11616 recorded day(s).
• WIGGINS FARMS WEST PUMP STATION (0100601) DWR↗☆: Observed p99 daily rate 19.8 cfs (max 30.9) exceeds total decreed absolute 3.3 cfs across 3551 recorded day(s).
• FLACK WELL NO 1-14525R (0106539) DWR↗☆: Observed p99 daily rate 18.1 cfs (max 18.1) exceeds total decreed absolute 1.7 cfs across 2538 recorded day(s).
• COCKROFT PUMP 1 (0100598) DWR↗☆: Observed p99 daily rate 17.3 cfs (max 22.4) exceeds total decreed absolute 4.6 cfs across 3209 recorded day(s).
• GROVES FARMS RECHARGE PUMP & PIPELINE (0100569) DWR↗☆: Observed p99 daily rate 17.2 cfs (max 64.1) exceeds total decreed absolute 16.4 cfs across 11109 recorded day(s).
• RIVERSIDE EMPIRE RECHARGE AREA (0102274) DWR↗☆: Observed p99 daily rate 16.0 cfs (max 16.0) exceeds total decreed absolute 14.4 cfs across 1406 recorded day(s).
• WESTERN SUGAR W 2-59300 (0109875) DWR↗☆: Observed p99 daily rate 13.1 cfs (max 14.8) exceeds total decreed absolute 6.6 cfs across 478 recorded day(s).
• RIVERSIDE GROVES S RECHARGE AREA (0102087) DWR↗☆: Observed p99 daily rate 12.8 cfs (max 14.6) exceeds total decreed absolute 10.8 cfs across 948 recorded day(s).

Seniority (top structures by decreed rate)

Recent inventory & legal-document changes

• 2026-10-10 — call set: SOUTH FLAT DITCH (39707)
• 2026-10-10 — call set: STERLING IRR CO DITCH 1 (39706)
• 2026-10-10 — call released: 39612
• 2026-10-09 — call released: 39680
• 2026-10-09 — call set: SOUTH PLATTE RIVER AT WATERTON (39697)
• 2026-10-09 — call set: CHATFIELD RESERVOIR (39698)
• 2026-10-09 — call released: 39678
• 2026-10-08 — call set: TRUE WEBSTER DITCH (39693)

Water-court filings this month (division-wide)

24 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 (17 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.