South Platte: Denver Gage to Greeley

Evolution of the network

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

Gage flow trend & changepoints

Of the 270 gages with enough record, 17 are trending down and 13 up, and 20 carry a detected shift. The clearest is Cherry Creek at Denver, its annual mean flow changing +3.60 cfs per decade (+13.6% of its median annual flow) over 68 years (p<0.0001). The other 235 show no clear signal either way. 1 transbasin gage meters imported or exported water — marked ⇆ below and kept out of these counts, because that flow is an operator's decision, not the basin's hydrology (all transbasin diversions).

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

⚠️ 7 gages flagged: their records may have quietly shifted against their neighbours, so treat their trends with caution.

235 other gage(s) show no significant trend or changepoint (not shown).

3 of those show a significant trend once extended backwards from a retired neighbour's record: So. Platte River below Brush Cr. near Trumbull (102 yr, increasing); North Fork South Platte River at Grant (87 yr, increasing); South Platte River below Union Ave, at Englewood,C (40 yr, decreasing). Those are reconstructions, not measurements — each gage's page shows both.

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. 198 gage(s) and 689 structure(s) report in 2026, but structure reporting only reached half its modern level around ~1973. 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: 4% of 10290 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 (1950–2025)

Mass-balance kinks computed for every summer month back to 1950 (1323 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.

• SOUTH PLATTE RIVER AT FORT LUPTON, CO.: reach shifted from +86 cfs to +539 cfs summer mean (more gaining, p=0.000, 70 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] [76 alluvial wells within 2 mi of the gage; pooled water table +1.1 ft (1929–2025, no_trend)]
• FIRST CR BEL BUCKLEY RD, AT ROCKY MTN ARSENAL, CO: reach shifted from -30 cfs to -16 cfs summer mean (more gaining, p=0.049, 14 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=0.53) -- part of it may be unaccounted water becoming accounted, not hydrologic change]

Groundwater now has its own tab: 8961 monitored well(s), water-table trends, stream corridors, and the advisory depletion screen.

Reservoirs now has its own tab: 284 reservoir(s), end-of-year storage back to 1950, click-to-chart histories.

Cross-gage pattern fingerprint

Over the 102-year window with full coverage (1925–2026), the dominant shared pattern across 3 gage(s) explains 82% 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 2026-07-25)

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.

• CHEROKEE EXCHANGE PIPELINE (diversion): -143.6 cfs (83% of that reach's correction)
• TWO FORKS RES (diversion): -134.8 cfs (31% of that reach's correction)
• AURORA INLET PL (diversion): -134.8 cfs (31% of that reach's correction)
• AURORA PL (diversion): -134.8 cfs (31% of that reach's correction)
• LAMMERS RES (diversion): +131.3 cfs (100% of that reach's correction)
• DENVER SPR4E LRF RELEASE (return): -28.7 cfs (17% of that reach's correction)
• DENVER FOOTHILLS PL 26 (diversion): -27.0 cfs (6% of that reach's correction)
• LUPTON BOTTOM D WEST LATERAL AUG RETURN (return): +16.6 cfs (33% of that reach's correction)
• AURORA EVERIST RESERVOIR 1 (diversion): +16.6 cfs (33% of that reach's correction)
• PLATTEVILLE D CENTRAL AUG RT (return): +16.6 cfs (33% of that reach's correction)

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

176,163 water-level measurements across 8961 monitored well(s) — 3556 alluvial, 2848 bedrock — plus 217 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 390 well(s) with enough record for a trend test: 157 declining, 53 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.

SOUTH PLATTE RIVER AT FORT LUPTON, CO.: 76 alluvial well(s) nearby; pooled water table +1.1 ft (1929–2025, no_trend, p=0.257). Glover screen: 3.2 cfs of nearby metered alluvial pumping → est. lagged depletion 2.8–3.1 cfs (uncalibrated T/S ranges; flagged for SPDSS calibration, AWAS cross-check, and expert review — DWR's AWAS is the authority).

FIRST CR BEL BUCKLEY RD, AT ROCKY MTN ARSENAL, CO: 62 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.

Source DWR administrative record · verify at DWR structure records ↗

284 reservoir(s) with 254,263 storage measurement(s), 1950–2025. Basin storage as of 2024-10-31 (the record's own end — reservoir records publish ~annually): 419,331 AF across 85 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 2026-09-08 · verify at U.S. Drought Monitor ↗

Right now

This is the 35th-driest week 35 in 132 years of record at SOUTH PLATTE RIVER AT DENVER (as of 2026-08-24; this week’s flow sits at the 27th 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, Park County is 15% in D4 exceptional drought (2026-09-08). The law agrees: the most senior active call leaves 0% of this district’s decreed flow rights junior to the calling right this week.

Every year since 1895, week by week

Each thin row is a year at SOUTH PLATTE RIVER AT DENVER; 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 35 weeks recorded so far, 2026’s weekly trace most resembles 2002 (mean gap 9.0 percentile points; next closest 1908 (12.4), 1981 (14.7)). 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, Arapahoe, Boulder, Broomfield, Clear Creek, Denver, Douglas, Jefferson, Logan, Morgan, Park, Pueblo, Sedgwick, 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.

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 2011 — 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 (1512 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 $447,890,017 in drought-caused claims across Adams, Arapahoe, Boulder, Broomfield, Clear Creek, Denver, Douglas, Jefferson, Logan, Morgan, Park, Pueblo, Sedgwick, Washington, Weld counties — 38.5% of all insured crop losses there. The worst year was 2022 ($122,163,264).

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 (25,447 rights across 132 years of shared record), colored by that year’s wetness from the barcode above. Here the correlation is -0.09 — 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 2026-09-08 · verify at EPA SDWIS ↗

63 systems touch this district (63 community systems reporting 3,237,629 people served, a figure that counts a wholesaler's customers twice); 1 of them carries an open health-based violation on EPA's record.

and 55 more; the full directory filters by district.

Instream-flow rights held by the state

Source Register of another agency · fetched 2026-09-13 · 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 1859-03-01 to 2024-11-18. Of the 20 structures with a yield estimate, the median one’s senior right was in priority 55% of a median irrigation season and 35% in a dry one. 25 abandonment screens and 296 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: 28314 across 21881 structure(s); 1172 structure(s) carry 1931 court-case references. Advisory reading aids on public DWR data — not administrative or legal conclusions.

Is the river getting harder to divert from?

Over 2012–2025, none of the three measures of administration (days under call, calls set, seniority of the controlling call) shows a significant trend — the river is being administered about as it was.

What the water is for — decade by decade

Of the water this district's structures diverted, the share whose decree includes municipal supply moved from 79% in the 1970s to 86% in the 2020s.

Why diversions stopped — call-based explanations

Sustained diversion stops matched to senior administrative calls.

• TCVS-01 (0200525) DWR↗☆ stopped 2025-10-02 (5+ days) — call at FARMERS IRRIGATION CANAL [heuristic-strong]
• TCVS-01 (0200525) DWR↗☆ stopped 2025-06-13 (50+ days) — call at NEW CACHE LA POUDRE CO DITCH [heuristic-strong]
• MILLIKEN RESERVOIR PUMP NO 1 (0200582) DWR↗☆ stopped 2024-11-30 (36+ days) — call at NORTH STERLING CANAL [heuristic-strong, district-confirmed]
• MILLIKEN RESERVOIR PUMP NO 1 (0200582) DWR↗☆ stopped 2024-08-31 (16+ days) — call at STERLING IRR CO DITCH 1 [heuristic-strong, district-confirmed]
• TCVS-01 (0200525) DWR↗☆ stopped 2024-08-17 (26+ days) — call at WESTERN MUTUAL DITCH [heuristic-strong, district-confirmed]
• TCVS-01 (0200525) DWR↗☆ stopped 2024-03-09 (6+ days) — call at BIJOU CANAL [heuristic-strong, district-confirmed]
• WESTERN SEEP DITCH (0200537) DWR↗☆ stopped 2023-10-15 (16+ days) — call at JACKSON LAKE INLET DITCH curtailing 100% of its decreed rate [heuristic-strong, district-confirmed]

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 (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 ~1973 — idleness that begins before then may be unreported use, not nonuse (flagged † below).

• HUGGINS DITCH (0801129) DWR↗☆ (1870-03-15, 1.0 cfs decreed): last active 1951 — 74 years idle † predates modern reporting era — last recorded activity predates this basin's modern reporting era (~1973) -- early absence of record is weak evidence of nonuse
• RANDALL D EXT CLAIM (2300988) DWR↗☆ (1878-08-01, 1.0 cfs decreed): last active 1951 — 74 years idle † predates modern reporting era — last recorded activity predates this basin's modern reporting era (~1973) -- early absence of record is weak evidence of nonuse
• FURMAN WASTE WATER DITCH (2300981) DWR↗☆ (1882-05-01, 10.0 cfs decreed): last active 1958 — 67 years idle † predates modern reporting era — last recorded activity predates this basin's modern reporting era (~1973) -- early absence of record is weak evidence of nonuse
• KESTER SWEET SPRINGS (2300543) DWR↗☆ (1876-12-31, 0.2 cfs decreed): last active 1962 — 63 years idle † predates modern reporting era — last recorded activity predates this basin's modern reporting era (~1973) -- early absence of record is weak evidence of nonuse
• 0200902 DWR↗☆ (1976-08-03, 100.0 cfs decreed): last active 1964 — 61 years idle † predates modern reporting era — last recorded activity predates this basin's modern reporting era (~1973) -- early absence of record is weak evidence of nonuse
• LITTLETON PL (0801462) DWR↗☆ (1861-08-30, 0.5 cfs decreed): last active 1968 — 57 years idle † predates modern reporting era — last recorded activity predates this basin's modern reporting era (~1973) -- early absence of record is weak evidence of nonuse
• 0200870 DWR↗☆ (1883-09-15, 13.0 cfs decreed): last active 1970 — 55 years idle † predates modern reporting era — last recorded activity predates this basin's modern reporting era (~1973) -- early absence of record is weak evidence of nonuse
• HAYMAN SPRG STOCK WTR DE (2301504) DWR↗☆ (1983-07-31, 0.0 cfs decreed): last active 1970 — 55 years idle † predates modern reporting era — last recorded activity predates this basin's modern reporting era (~1973) -- early absence of record is weak evidence of nonuse
• HURST SPRING 1 (2301589) DWR↗☆ (1932-06-21, 0.1 cfs decreed): last active 1970 — 55 years idle † predates modern reporting era — last recorded activity predates this basin's modern reporting era (~1973) -- early absence of record is weak evidence of nonuse
• TOMS SPRING 1 (2301639) DWR↗☆ (1961-09-02, 0.1 cfs decreed): last active 1970 — 55 years idle † predates modern reporting era — last recorded activity predates this basin's modern reporting era (~1973) -- early absence of record is weak evidence of nonuse

Compliance screens (296 advisory flags)

Screened 552 of 21881 structures with rights (762 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.

• LORENZ TRUST 4-R12939 (0207026) DWR↗☆: Observed p99 daily rate 123904.7 cfs (max 123904.7) exceeds total decreed absolute 4.3 cfs across 12 recorded day(s).
• LOWER PLUM CREEK DITCH LEFT IN STREAM (0802922) DWR↗☆: Observed p99 daily rate 338.8 cfs (max 475.5) exceeds total decreed absolute 5.0 cfs across 5146 recorded day(s).
• MILTON RES (0203876) DWR↗☆: Observed p99 daily rate 256.0 cfs (max 602.1) exceeds total decreed absolute 50.0 cfs across 34963 recorded day(s).
• ANTERO RES (2303904) DWR↗☆: Observed p99 daily rate 215.0 cfs (max 462.0) exceeds total decreed absolute 6.0 cfs across 11185 recorded day(s).
• 0200902 DWR↗☆: Observed p99 daily rate 141.0 cfs (max 141.0) exceeds total decreed absolute 100.0 cfs across 36 recorded day(s).
• MONTGOMERY RES (2303962) DWR↗☆: Observed p99 daily rate 110.5 cfs (max 261.5) exceeds total decreed absolute 0.5 cfs across 40688 recorded day(s).
• WHIPPLE DITCH (0200871) DWR↗☆: Observed p99 daily rate 94.6 cfs (max 143.0) exceeds total decreed absolute 6.0 cfs across 10045 recorded day(s).
• SECTION NO 3 DITCH (0200830) DWR↗☆: Observed p99 daily rate 58.0 cfs (max 141.0) exceeds total decreed absolute 57.7 cfs across 33792 recorded day(s).
• CANON DITCH (2300694) DWR↗☆: Observed p99 daily rate 50.0 cfs (max 50.0) exceeds total decreed absolute 35.4 cfs across 2574 recorded day(s).
• EAST NERES CANAL (0200919) DWR↗☆: Observed p99 daily rate 49.6 cfs (max 185.9) exceeds total decreed absolute 25.0 cfs across 13610 recorded day(s).

Seniority (top structures by decreed rate)

Recent inventory & legal-document changes

• 2026-09-11 — call set: B H EATON DITCH (39462)
• 2026-09-11 — call released: 39455
• 2026-09-11 — legal document update: LOWER LATHAM DITCH (0200834) (new case(s): 16CW3196)
• 2026-09-11 — call set: B H EATON DITCH (39455)
• 2026-09-11 — call set: BONUS DITCH (39461)
• 2026-09-11 — call released: 39201
• 2026-09-11 — call released: 39439
• 2026-09-09 — call set: COFFIN DAVIS DRY CREEK DIVERSION (39447)

Water-court filings this month (division-wide)

16 applications in the 2026-07 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 2026-09-30 (15 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.

Showing 25 of 63 plans — the rest are on DWR’s register.

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.