South Platte Cheesman to Denver Gage

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 2026-10-08 (the newest reading on file), flows at the 1 ranked gage are running at a median 99% of their own long-term norm for this window — 1 below a typical year, 0 at or above. Driest relative to its record: SOUTH PLATTE RIVER AT LAST CHANCE DIVERSION NEAR KASSLER, ranking 4th lowest of 9 years.

Gage flow trend & changepoints

Of the 72 gages with enough record, 4 are trending down and 4 up, and 6 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 62 show no clear signal either way.

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

⚠️ 1 gage flagged: their records may have quietly shifted against their neighbours, so treat their trends with caution.

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

2 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); 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. 51 gage(s) and 157 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: 3% of 3820 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.

Groundwater now has its own tab: 3026 monitored well(s), water-table trends, stream corridors, and the advisory depletion screen.

Reservoirs now has its own tab: 47 reservoir(s), end-of-year storage back to 1950, click-to-chart histories.

Cross-gage pattern fingerprint

Over the 101-year window with full coverage (1926–2026), the dominant shared pattern across 3 gage(s) explains 81% 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 2026-09-25)

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.

• TWO FORKS RES (diversion): -93.3 cfs (25% of that reach's correction)
• AURORA INLET PL (diversion): -93.3 cfs (25% of that reach's correction)
• AURORA PL (diversion): -93.3 cfs (25% of that reach's correction)
• DENVER FOOTHILLS PL 26 (diversion): -93.3 cfs (25% of that reach's correction)
• COLEMAN PL (diversion): -78.6 cfs (33% of that reach's correction)
• WILLRICH SPRING (return): -78.6 cfs (33% of that reach's correction)
• LUCKY JACK SPRING (return): -78.6 cfs (33% of that reach's correction)
• DENVER CONDUIT NO 20 (diversion): -32.1 cfs (100% of that reach's correction)
• ARAPAHOE POWER PLANT (diversion): +18.4 cfs (100% of that reach's correction)
• ISBELL SPRING 1 (return): +9.8 cfs (17% of that reach's correction)

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

36,122 water-level measurements across 3026 monitored well(s) — 735 alluvial, 1430 bedrock — plus 160 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 179 well(s) with enough record for a trend test: 86 declining, 17 rising.

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 ↗

47 reservoir(s) with 34,555 storage measurement(s), 1950–2026. Basin storage as of 2025-10-31 (the record's own end — reservoir records publish ~annually): 49,340 AF across 5 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 Independent agency measurement · fetched 2026-10-14 · verify at NRCS report generator ↗ Source Our computation, scored against a reference · NRCS forecast, graded here against the gage record

Snow-water equivalent, WY2027

NRCS SNOTEL, daily. Sites are assigned to the district whose boundary contains them — the snow that feeds this district can also sit in a neighboring headwater district.

Runoff outlook — South Platte R at South Platte

NRCS's final issue (2026-06-01) calls it even odds that at least 58 kAF arrives over 06-01 to 09-30 — 44% of a normal season; almost certainly at least 29, probably not more than 91. Our own record at this gage shows 110 kAF actually delivered. New forecasts begin in January. How to read these numbers →

We test a record-based adjustment of the April benchmark at every graded point. Here it did not beat NRCS over 78 replayed seasons (23% typical miss unadjusted vs 21% adjusted), so none is shown — NRCS’s own forecast, unadjusted, is the best April benchmark available for this river. Why we test →

How good are these forecasts here? (1979–2026)

Grading every April issue against what the river then delivered, measured at this gage’s own record — 47 seasons: the median miss of the 50% forecast is 25%, with a low bias of 19%, and the observed volume landed inside the stated 10–90% band 82% of the time (a calibrated forecast would say 80%).

Computed by this site: NRCS's archived April issues (their period as issued each year) against the observed volume in DWR’s published record; years with under 90% daily coverage are dropped, not summed. A grade of the forecast, never of the forecasters — these are hard rivers. How this point ranks among every graded Colorado forecast point →

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 91st-driest week 39 in 132 years of record at SOUTH PLATTE RIVER AT DENVER (as of 2026-09-21; this week’s flow sits at the 69th 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, Jefferson County is 44% 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 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 39 weeks recorded so far, 2026’s weekly trace most resembles 2002 (mean gap 11.3 percentile points; next closest 1908 (13.1), 1934 (15.6)). 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 Arapahoe, Denver, Douglas, Jefferson 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 1950 — 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 (1221 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 $27,520,820 in drought-caused claims across Arapahoe, Denver, Douglas, Jefferson counties — 55.3% of all insured crop losses there. The worst year was 2022 ($4,231,473).

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 (14,945 rights across 132 years of shared record), colored by that year’s wetness from the barcode above. Here the correlation is -0.04 — 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 ↗

75 systems touch this district (75 community systems reporting 2,962,404 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 67 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 ↗

11 reaches over 82.4 miles, held by the Colorado Water Conservation Board so that water stays in the stream. Every reach, with its schedule and case →

• West Creek, 13.4 mi: 1.5 (1/1 - 12/31) cfs (appropriated 1980, 80CW0212) · dossier
• Trout Creek, 11.0 mi: 2 (1/1 - 12/31) cfs (appropriated 1977, 77W8731) · dossier
• Trail Creek, 10.0 mi: 1 (1/1 - 12/31) cfs (appropriated 1977, 77W8732) · dossier
• Turkey Creek, 9.9 mi: 2 (1/1 - 12/31) cfs (appropriated 1980, 80CW0208) · dossier
• Jackson Creek, 9.2 mi: 3 (4/1 - 8/31), 1 (9/1 - 3/31) cfs (appropriated 1986, 86CW0294) · dossier
• West Creek, 6.6 mi: 4 (1/1 - 12/31) cfs (appropriated 1980, 80CW0211) · dossier

and 5 more on the district's instream-flow page.

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 2024-09-03. Of the 20 structures with a yield estimate, the median one’s senior right was in priority 5% of a median irrigation season and 0% in a dry one. 25 abandonment screens and 78 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: 16434 across 12310 structure(s); 0 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 1951–2025, administration on this district has been tightening: 2 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.

• CASTLE ROCK SURFACE DIVERSION 1 (0800534) DWR↗☆ stopped 2025-08-06 (19+ days) — call at WESTERN MUTUAL DITCH curtailing 100% of its decreed rate [heuristic-strong, district-confirmed]
• PLUM CREEK DIVERSION (0800525) DWR↗☆ stopped 2025-06-03 (5+ days) — call at PREWITT INLET CANAL curtailing 100% of its decreed rate [heuristic-strong, district-confirmed]
• PLUM CREEK DIVERSION (0800525) DWR↗☆ stopped 2025-03-03 (6+ days) — call at NORTH STERLING CANAL curtailing 100% of its decreed rate [heuristic-strong]
• PLUM CREEK DIVERSION (0800525) DWR↗☆ stopped 2024-11-06 (60+ days) — call at CITY DITCH PL curtailing 100% of its decreed rate [heuristic-strong, district-confirmed]
• CASTLE ROCK SURFACE DIVERSION 1 (0800534) DWR↗☆ stopped 2024-10-24 (94+ days) — call at DENVER CONDUIT NO 20 curtailing 100% of its decreed rate [heuristic-strong, district-confirmed]
• PLUM CREEK DIVERSION (0800525) DWR↗☆ stopped 2024-09-27 (6+ days) — call at BURLINGTON D RIVER HEADGATE curtailing 100% of its decreed rate [heuristic-strong, district-confirmed]
• CHATFIELD ARBORETUM WETLANDS INLET DITCH (0800524) DWR↗☆ stopped 2024-06-28 (6+ days) — call at STERLING IRR CO DITCH 1 curtailing 100% of its decreed rate [heuristic-strong, district-confirmed]
• PLUM CREEK DIVERSION (0800525) DWR↗☆ stopped 2024-06-09 (8+ days) — call at STERLING IRR CO DITCH 1 curtailing 100% of its decreed rate [heuristic-strong, district-confirmed]
• CHATFIELD ARBORETUM WETLANDS INLET DITCH (0800524) DWR↗☆ stopped 2024-05-21 (24+ days) — call at HARMONY DITCH 1 curtailing 100% of its decreed rate [heuristic-strong, district-confirmed]
• CASTLE ROCK SURFACE DIVERSION 1 (0800534) DWR↗☆ stopped 2024-05-12 (9+ days) — call at BURLINGTON D RIVER HEADGATE curtailing 100% of its decreed rate [heuristic-strong, district-confirmed]
• PLUM CREEK DIVERSION (0800525) DWR↗☆ stopped 2024-03-05 (21+ days) — call at BURLINGTON D RIVER HEADGATE curtailing 100% of its decreed rate [heuristic-strong, district-confirmed]
• PLUM CREEK DIVERSION (0800525) DWR↗☆ stopped 2024-01-13 (31+ days) — call at LITTLETON BOAT CHUTE NO 9 curtailing 100% of its decreed rate [heuristic-partial, 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 — 73 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 — 56 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
• STEWART DITCH (0801212) DWR↗☆ (1874-04-01, 2.7 cfs decreed): last active 1973 — 51 years idle
• BALL DITCH (0801213) DWR↗☆ (1872-04-19, 0.3 cfs decreed): last active 1973 — 51 years idle
• CONEHAY DITCH (0801360) DWR↗☆ (1892-08-19, 1.9 cfs decreed): last active 1973 — 51 years idle
• ADKINS PL & DITCH (0801456) DWR↗☆ (1920-06-29, 0.6 cfs decreed): last active 1973 — 51 years idle
• MARTHA E HIGSON DITCH (0801458) DWR↗☆ (1876-04-01, 0.1 cfs decreed): last active 1973 — 51 years idle
• DEVINNY RES 2 (0803946) DWR↗☆ (1893-11-01, 0.0 cfs decreed): last active 1973 — 51 years idle
• HOCKADAY WELL (0805019) DWR↗☆ (1955-06-01, 0.1 cfs decreed): last active 1973 — 51 years idle
• DENVER C C W BATT 1 (0805024) DWR↗☆ (1902-06-16, 5.5 cfs decreed): last active 1973 — 51 years idle

Compliance screens (78 advisory flags)

Screened 144 of 12310 structures with rights (209 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.

• 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).
• PLATTE CANON DITCH (0801005) DWR↗☆: Observed p99 daily rate 39.0 cfs (max 43.0) exceeds total decreed absolute 5.7 cfs across 1396 recorded day(s).
• SOUTH PLATTE LAKE (0804097) DWR↗☆: Observed p99 daily rate 23.7 cfs (max 61.0) exceeds total decreed absolute 5.2 cfs across 14451 recorded day(s).
• WAUCONDAH RES (0803516) DWR↗☆: Observed p99 daily rate 20.2 cfs (max 152.3) exceeds total decreed absolute 3.0 cfs across 6858 recorded day(s).
• DENVER C C W BATT 1 (0805024) DWR↗☆: Observed p99 daily rate 17.0 cfs (max 17.0) exceeds total decreed absolute 5.5 cfs across 180 recorded day(s).
• EAST PLUM CR DITCH (0801180) DWR↗☆: Observed p99 daily rate 10.6 cfs (max 10.6) exceeds total decreed absolute 10.6 cfs across 7990 recorded day(s).
• LAKEWOOD CC PUMP 1 (0805034) DWR↗☆: Observed p99 daily rate 10.5 cfs (max 10.5) exceeds total decreed absolute 3.3 cfs across 330 recorded day(s).
• BROWN DITCH (0801011) DWR↗☆: Observed p99 daily rate 10.0 cfs (max 16.0) exceeds total decreed absolute 3.8 cfs across 8516 recorded day(s).
• LOWER PLUM CREEK DITCH (0801161) DWR↗☆: Observed p99 daily rate 8.0 cfs (max 8.0) exceeds total decreed absolute 6.0 cfs across 1052 recorded day(s).
• ALDERMAN DITCH (0801400) DWR↗☆: Observed p99 daily rate 8.0 cfs (max 8.0) exceeds total decreed absolute 5.0 cfs across 3204 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 (16 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.

The water itself, in this district

Four registers, each on its own schedule: what USGS sensors read right now, where samples have been taken, which stretches the state lists as impaired, and how the tap water of the systems here stands with EPA. None is a DWR record; each links its own page.

Right now

Source Provisional telemetry · fetched 2026-10-15 · verify at USGS current conditions ↗

3 USGS sensors report temperature, conductance, dissolved oxygen or turbidity from inside this district; provisional readings, never merged into the verified record.

Where water has been sampled

Source Register of another agency · fetched 2026-10-08 · verify at Water Quality Portal ↗

The portal lists 10,211 sampling stations in this district's watersheds (Upper South Platte 10190002, 67% of the district; Middle South Platte-Cherry Creek 10190003, 32% of the district), of which 360 reported a sample in the last 5 years on the state and tribal side (USGS activity is in the station count, not in that figure). Most active: Colorado Dept. of Public Health & Environment-WQCD (188), Colorado River Watch (57), USGS Colorado Water Science Center (56). Most-sampled groups: Inorganics, Major, Metals, Physical, Nutrient, Organics, Pesticide. Every station as a file ↗

Results themselves are not fetched here; USGS samples added after March 2024 may not be in the portal's legacy profiles yet.

Drinking water

Source Register of another agency · fetched 2026-10-07 · verify at EPA SDWIS ↗

75 community systems touch this district. 4 carry an open health-based violation on EPA's record; 2 are listed by EPA as serious violators. EPA sampled 23 of them for PFAS in 2023–25; 5 had PFOA or PFOS at or above the 2024 limit.

and 65 more; the full directory filters by district.

EPA's record carries violations and lead/copper percentiles; nitrate and disinfection by-product results are not in it. UCMR 5 samples are monitoring, not compliance, and the 2024 PFOA/PFOS limits equal its reporting limit, so any detection of those two is at or above them.

Impaired waters

Source Register of another agency · verify at EPA ATTAINS ↗

The state's 303(d) impaired-waters list has not been joined to this basin's own watershed boundary yet, so nothing is shown rather than a guess; the basins with a join carry the full list here. Why the join is geometry, not a name match.