Boulder Creek

Division 1 · Water District 6 · As of 2026-10-12 00:37 MDT · 4 days ago

Who may take water from the Boulder Creek, who is calling for it today, and how it is running, compiled from Colorado Division of Water Resources records. Click anything on the map for its record.

Live · reviewed by a person

How this page was built

Rebuilt 2026-10-16 12:24 UTC from 8,263 input files: two runs agree (output f2b2a46180f5e3c8…); not compared with the analysis served here (why?). The receipt

Boulder Creek on the ground — the ditches, wells, reservoirs and gages of Water District 6 · clicktap anything for its record

The well-permit cells in view, as a table

Each row is one ~1-mile cell (0.02°) with the permits the file spots inside it, split into water-supply permits and monitoring holes (DWR’s two monitoring categories: drilled to look at the water, not to pump it). These are permits, not wells: a permit is a piece of paper, and the file does not say which were drilled. Spotting is the file’s own, about a mile at best, which is why the cells are no finer.

Lat	Lon	Water-supply permits	Monitoring holes

Browse this district’s ditches, gages, reservoirs, wells and springs as a list.

4% of normal flow, week of 2026-09-21

2 calls the record places on it, 6 unsettled

The South Boulder Creek is critically low for late September -- 4% of normal flow, its 5th-driest such week in 128 years of record. 2 calls stand against it right now; the most senior right calling dates to 1860. DWR's statements do not settle whether 6 more calls reach it. This year's runoff outlook, issued 2026-06-01, called for 56% of normal.

Schematic

Historical

Reconstruct conditions as of

Evolution of the network

Trends

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

What counts as a trend here

Computed 2026-10-12 00:49 from 104 gage(s) with cached period-of-record data. The series is each gage's annual mean flow in cfs (years with ≥300 days of record). Mann-Kendall (trend, with the Hamed–Rao correction for serial correlation — persistence can otherwise fake significance) and Pettitt (changepoint) both require at least 8 years spanning at least 10 years of record. A gage below that reports no signal — which is not the same as “no change.” The %-per-decade figure is the same Sen slope divided by the gage's median annual flow, for comparing across streams of very different size; it is omitted for near-ephemeral channels where the median is too small to divide by honestly.

Of the 104 gages with enough record, 7 are trending down and 2 up, and 9 carry a detected shift. The clearest is South Boulder Creek near Eldorado Springs, its annual mean flow changing -4.02 cfs per decade (-6.2% of its median annual flow) over 127 years (p<0.0001). The other 93 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.

Gage	Trend	Change / decade cfs · % of median annual flow	Significance	Years	Changepoint
▸ South Boulder Creek near Eldorado Springs BOCELSCO	↓ decreasing	-4.02 cfs -6.2%	p<0.001	127	~1962
▸ Boulder Creek near Orodell BOCOROCO	↓ decreasing	-4.48 cfs -5.4%	p<0.001	116	~1962
▸ Middle Boulder Creek at Nederland BOCMIDCO	↓ decreasing	-1.52 cfs -2.7%	p<0.001	119	~1962
▸ South Boulder Creek below Gross Reservoir BOCBGRCO	↓ decreasing	-6.39 cfs -4.7%	p<0.001	58	~2006
▸ South Boulder Creek Diversion near Eldorado Springs BOSDELCO	↓ decreasing	-4.30 cfs -5.2%	p<0.001	61	~1991
▸ Fourmile Creek at Orodell FOUOROCO	↓ decreasing	-1.30 cfs -20.4%	p=0.002	18	~1987
▸ Boulder Creek at Mouth near Longmont BOCLONCO	↑ increasing	+3.93 cfs +6.2%	p=0.008	73	~1955
▸ Boulder Creek at North 75th St. near Boulder BOCNORCO	↓ decreasing	-6.80 cfs -7.9%	p=0.037	39	~2001
▸ ⇆ Moffat Water Tunnel at East Portal MOFTUNCO	↓ decreasing	-2.04 cfs -3.0%	p=0.043	83	—
▸ South Boulder Creek near Rollinsville SOBOROCO	↑ increasing	+12.92 cfs +14.1%	p=0.049	10	—
▸ ⚠️ North Boulder Creek at Silver Lake NOBOSICO	no clear trend	+6.93 cfs +21.9%	p=0.344	16	~1919

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

How drift is detected

Every gage's annual flows are compared against each neighbour's as a double-mass curve (Searcy & Hardison, USGS WSP 1541-B); a Pettitt step test looks for a break in the ratio. A gage is flagged only when the breaks AGREE across its references, and a break against an already-suspect gage is never counted against a healthy one. A double-mass break means the ratio between two gages changed, not that either gage is faulty: a new diversion, a reservoir, or an import changes that ratio exactly as a rating shift does. Screening aid for expert review, never a measurement verdict.

93 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. 92 gage(s) and 86 structure(s) report in 2026, but structure reporting only reached half its modern level around ~1950. Every historical claim below is checked against this: long-term shifts that co-move with the growth of the network carry an explicit measurement-evolution caution, and abandonment screens whose idleness begins before the modern reporting era are flagged †.

Decade	Gages with data (median yr)	Structures reporting (median yr)
1890s	1	0
1900s	2	0
1910s	4	0
1920s	4	0
1930s	5	0
1940s	5	0
1950s	6	60
1960s	7	56
1970s	11	58
1980s	13	64
1990s	12	78
2000s	13	84
2010s	18	90
2020s	80	84

Mass-balance (network closure) trend

Structure divrec-history backfill coverage as of the last check: 34% of 225 schematic-relevant structures. Kink count trend: increasing (p=0.001), kink magnitude trend: no_trend (p=0.592) across 10 qualifying year(s).

Reach gain/loss shifts (1950–2026)

Mass-balance kinks computed for every summer month back to 1950 (2413 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 BOULDER CREEK DIVERSION NEAR ELDORADO SPRINGS: reach shifted from -122 cfs to +19 cfs summer mean (more gaining, p=0.000, 62 yr) [crystalline foothills: minimal groundwater storage -- large or shifting unaccounted losses here are more consistent with data/measurement issues or unmodeled plumbing than with aquifer exchange] [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]

Groundwater now has its own tab: 536 monitored well(s), water-table trends, stream corridors, and the advisory depletion screen.

Reservoirs now has its own tab: 64 reservoir(s), end-of-year storage back to 1950, click-to-chart histories.

Cross-gage pattern fingerprint

Over the 111-year window with full coverage (1916–2026), the dominant shared pattern across 3 gage(s) explains 78% 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 2026-09-24)

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.

DAVIS RES 1&2 (diversion): +27.0 cfs (100% of that reach's correction)
LAFAYETTE BLDR C ALT PT (diversion): -18.8 cfs (100% of that reach's correction)
BULL HEAD GULCH P L (diversion): -13.8 cfs (50% of that reach's correction)
GOOSE HAVEN POND 2 (diversion): -13.8 cfs (50% of that reach's correction)
WELLMAN DITCH (diversion): +10.0 cfs (100% of that reach's correction)
STROMQUIST POND 1 (diversion): +9.3 cfs (100% of that reach's correction)
S BOULDER DIVR CONDUIT (diversion): -7.7 cfs (100% of that reach's correction)
HARTMAN RES (diversion): +7.7 cfs (25% of that reach's correction)
LAFAYETTE BOULDER C PL 1 (diversion): +7.7 cfs (25% of that reach's correction)
KUGELER PIPELINE 1 (diversion): +7.7 cfs (25% of that reach's correction)

Data provenance & quality

Where these numbers come from and how far they can be trusted. Grade B (4/6 points) — the components below are the finding; the letter alone is not. Sources: DWR HydroBase snapshot HydroBase_CO_20260928 (imported 2026-10-04) for history, plus the CDSS REST API for current conditions.

Check	State	What was measured
gage freshness	current	newest gage reading is 2 day(s) old
diversion record	expected-lag	newest diversion record is 346 day(s) old (DWR publishes ~1 year in arrears)
structure coverage	sparse	34% of schematic structures have data

Independent check: PASS — 100.0000% agreement across 304,701 stored values re-checked against DWR's authoritative record (HydroBase_CO_20260707), over 20 structures. 0 disagreement(s) beyond a 0.01 cfs tolerance. Checked 2026-08-19; a rotating sample covers the whole basin across successive runs, and the structures this report cites are checked every time.

Federal cross-check: WARN — 94.80% day-level agreement with USGS's own published records for the same gages, across 14 co-listed station(s) and 147,201 overlapping days (within max(2%, 0.5 cfs) daily). Pre-1950 records at some gages carry known between-agency day-stamp and transcription differences — scored at each year's best ±1-day alignment; residual disagreement is real historical divergence, flagged for review.

104 gage(s) / 555,438 daily values (1896-01-01–2026-10-10); 213 structure(s) with diversion records; 1867 with decreed rights. Methodology has not yet had independent expert review — treat every figure as an advisory screen, not an administrative or legal conclusion.

Groundwater

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

1,545 water-level measurements across 536 monitored well(s) — 242 alluvial, 80 bedrock — plus 2 administered well(s) reporting metered pumping.

What is being counted

Observation wells and pumping wells are different populations and are never conflated: water levels come from monitored observation wells, and metered pumping comes from administered wells reporting through diversion records. Click any well to chart its own record.

Well map

3D aquifer x-ray

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

How the surfaces are built, and what they are not

Alluvial water table on top, Denver Basin members (Dawson, Denver, Arapahoe, Laramie–Fox Hills) stacked beneath where measured, interpolated from measured water levels. Units are never mixed; a surface exists only inside its own unit's well coverage, with no extrapolation; thin epochs are suppressed and say why. Vertical scale is exaggerated for readability and z is head elevation in feet. These are measured heads, not a calibrated groundwater model.

Water-table trends

Of 3 well(s) with enough record for a trend test: 1 declining, 2 rising.

Fastest-declining wells	Setting	ft / decade	Span	p
▸ SC00106931CBD	unknown	-26.2	11 yr	0.0007

Stream corridors — the surface connection

Where a reach's gain or loss has shifted, the wells within two miles of its anchoring gage and what their water table did over the same era.

How the corridor is assembled

For each reach whose gain/loss has shifted (Trends tab): the wells within 2 miles of its anchoring gage, their pooled water-table history over the same era, and an advisory Glover screen of lagged stream depletion from nearby metered pumping. v1 proximity = distance to the reach's anchoring gage; segment-based reach join is a flagged upgrade.

SOUTH BOULDER CREEK DIVERSION NEAR ELDORADO SPRINGS: 2 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.

18,811 well permits on file — not decreed rights

67% household or domestic use

177 ft median depth, 12,426 wells reporting

57% are constructed wells; 4% tie to a decreed structure. A permit is permission to drill, not a water right; most here are exempt household wells. More in three things called “well”, or turn on the Well permits chip on the map above to see where they sit.

Permits issued here, by year

10,692 located water-supply permits with an issue date, 1900 to 2026; half of them had been issued by 1986, and the busiest year was 1972 with 862. The district’s 3,487 monitoring holes are counted apart: they are drilled to look, not to pump. A permit is not a well, and the year is the date the paper was issued, not a drilling date. The 18,811 above counts every permit on file here; 4,632 of them have no usable location or no issue date and are not in this chart.

Show the monitoring holes too (3,487; the scale changes)

water-supply permits issued that year monitoring holes, when shown 5 issued before 1950 are in the table, not the bars

The counts by year, as a table

Located well permits with an issue date in this district, by issue year. Monitoring holes are the two DWR monitoring categories; water-supply is everything else.
Year	Issued	Monitoring holes	Water-supply	Issued through that year
1900	1	0	1	1
1909	1	0	1	2
1945	3	0	3	5
1953	29	0	29	34
1954	61	0	61	95
1955	100	0	100	195
1956	77	0	77	272
1957	66	0	66	338
1958	46	0	46	384
1959	42	0	42	426
1960	64	0	64	490
1961	54	0	54	544
1962	68	0	68	612
1963	102	0	102	714
1964	81	0	81	795
1965	71	0	71	866
1966	89	0	89	955
1967	73	0	73	1,028
1968	90	0	90	1,118
1969	99	0	99	1,217
1970	85	0	85	1,302
1971	167	0	167	1,469
1972	862	0	862	2,331
1973	344	0	344	2,675
1974	153	0	153	2,828
1975	122	0	122	2,950
1976	137	1	136	3,087
1977	262	0	262	3,349
1978	385	0	385	3,734
1979	319	0	319	4,053
1980	207	0	207	4,260
1981	211	3	208	4,471
1982	187	2	185	4,658
1983	205	1	204	4,863
1984	170	0	170	5,033
1985	177	2	175	5,210
1986	197	9	188	5,407
1987	197	16	181	5,604
1988	215	63	152	5,819
1989	199	43	156	6,018
1990	288	106	182	6,306
1991	320	111	209	6,626
1992	370	181	189	6,996
1993	356	127	229	7,352
1994	506	257	249	7,858
1995	408	158	250	8,266
1996	332	118	214	8,598
1997	275	98	177	8,873
1998	248	64	184	9,121
1999	303	99	204	9,424
2000	382	188	194	9,806
2001	233	51	182	10,039
2002	346	93	253	10,385
2003	215	95	120	10,600
2004	230	112	118	10,830
2005	190	97	93	11,020
2006	99	24	75	11,119
2007	122	25	97	11,241
2008	123	40	83	11,364
2009	167	100	67	11,531
2010	102	49	53	11,633
2011	93	23	70	11,726
2012	91	13	78	11,817
2013	108	52	56	11,925
2014	175	107	68	12,100
2015	129	40	89	12,229
2016	179	92	87	12,408
2017	149	51	98	12,557
2018	202	107	95	12,759
2019	170	77	93	12,929
2020	167	88	79	13,096
2021	186	90	96	13,282
2022	194	80	114	13,476
2023	202	76	126	13,678
2024	181	80	101	13,859
2025	220	151	69	14,079
2026	100	27	73	14,179

Every district in the file on one scale · the whole file, one year at a time · Plate 4 of the Driller’s Atlas.

What drillers reached, township by township

12 PLSS townships here where at least 5 water-supply permits naming the same aquifer filed a depth (9,797 permits in all). Each column is one township, six miles square, on one scale to 1,300 ft below ground: a faint lane spans the 10th to 90th percentile of where the permits naming that aquifer stopped, the solid band their screens, the tick the median. This is the permit file’s view of the ground — the aquifer is the name the driller wrote, the band is where those holes ended — not a geologic map, and a township is as fine as it gets. Monitoring holes are left out. Columns are drawn to 3,000 ft at most; 1 band here runs deeper and is drawn to the bottom edge with an arrow, the numbers as filed in the table: T1N R68W unnamed (222 permits, 90th percentile 14,020 ft). 5 of these townships straddle a district line and are filed here because most of their permits are.

T1N R71W
1,789 · 75% here

T1S R72W
1,542

T1N R70W
1,361 · 94% here

T1S R70W
1,139

T2S R71W
1,069 · 84% here

T1N R69W
620

T1S R71W
615

T1N R72W
488 · 78% here

T1S R73W
476

T1S R69W
424

T1N R68W
269 · 63% here

T1S R74W
5

unnamed alluvium Laramie-Fox Hills fractured crystalline other named faint = where the permits naming it stopped (10th–90th pct) · solid = their screens · tick = median · arrow = runs deeper than the scale · ft below ground as filed

Every township here, as a table

Water-supply permits by PLSS township and the aquifer named on them, where at least 5 filed a depth: percentiles of the depth drilled to and of the screen top and bottom (where at least 5 filed a screen), feet below ground as filed. The permit file’s view, not a geologic map.
Township	Share of its permits in this district	Aquifer named	Permits with a depth	Drilled depth p10 / p50 / p90, ft	Screen top p10 / p50 / p90, ft	Screen bottom p10 / p50 / p90, ft
T1N R71W 6th PM	75%	unnamed	1,774	48 / 300 / 600	15 / 180 / 422	161 / 380 / 617
T1N R71W 6th PM	75%	fractured crystalline	9	466 / 700 / 820	273 / 560 / 648	429 / 660 / 834
T1S R72W 6th PM	98%	unnamed	1,524	95 / 298 / 550	15 / 160 / 400	140 / 305 / 560
T1S R72W 6th PM	98%	fractured crystalline	17	312 / 433 / 641	240 / 360 / 442	402 / 452 / 602
T1N R70W 6th PM	94%	alluvium	11	14 / 17 / 36	6 / 10 / 16	14 / 16 / 36
T1N R70W 6th PM	94%	unnamed	1,331	16 / 35 / 200	8 / 12 / 40	15 / 30 / 200
T1N R70W 6th PM	94%	Laramie-Fox Hills	15	102 / 220 / 286	12 / 23 / 46	80 / 160 / 240
T1S R70W 6th PM	100%	alluvium	6	12 / 16 / 19	—	—
T1S R70W 6th PM	100%	other named	7	20 / 100 / 447	—	—
T1S R70W 6th PM	100%	unnamed	1,046	20 / 200 / 408	10 / 80 / 299	20 / 232 / 500
T1S R70W 6th PM	100%	Laramie-Fox Hills	79	200 / 375 / 540	60 / 200 / 346	218 / 375 / 520
T2S R71W 6th PM	84%	alluvium	7	13 / 17 / 522	9 / 10 / 183	13 / 17 / 514
T2S R71W 6th PM	84%	unnamed	1,048	80 / 350 / 776	30 / 230 / 527	185 / 418 / 837
T2S R71W 6th PM	84%	fractured crystalline	12	333 / 690 / 1,226	276 / 326 / 623	648 / 960 / 1,132
T1N R69W 6th PM	98%	unnamed	578	38 / 200 / 400	13 / 50 / 260	42 / 200 / 475
T1N R69W 6th PM	98%	Laramie-Fox Hills	35	100 / 315 / 532	15 / 140 / 320	59 / 370 / 526
T1S R71W 6th PM	99%	unnamed	612	95 / 320 / 696	25 / 216 / 480	190 / 405 / 741
T1N R72W 6th PM	78%	unnamed	483	65 / 260 / 500	14 / 140 / 380	140 / 300 / 520
T1S R73W 6th PM	99%	unnamed	473	27 / 150 / 400	15 / 84 / 310	40 / 185 / 420
T1S R69W 6th PM	96%	unnamed	366	28 / 300 / 632	20 / 228 / 445	35 / 410 / 635
T1S R69W 6th PM	96%	Laramie-Fox Hills	53	275 / 600 / 798	148 / 380 / 510	275 / 590 / 754
T1N R68W 6th PM	63%	unnamed	222	30 / 130 / 14,020 (off the drawn scale)	15 / 49 / 485	34 / 110 / 690
T1N R68W 6th PM	63%	Laramie-Fox Hills	42	520 / 655 / 839	261 / 430 / 658	504 / 650 / 828
T1S R74W 6th PM	100%	unnamed	5	128 / 240 / 416	—	—

These columns on the map · Plate 6 of the Driller’s Atlas.

The Driller’s Atlas · Plate 2 A cross-section nobody surveyed

Every permitted well within a few miles of the line, drawn from the ground to its drilled depth as the driller filed it. The bright part of each stroke is the perforated casing — where the well actually takes water — coloured by the aquifer named on the permit. Nobody arranged these; the aquifers arrange themselves.

Line Corridor

Hover or arrow through the strokes to read a well.

The same corridor as a table


Miles from A	Wells drawn	Median depth (ft)	With a screen	Most-named aquifer	No depth filed	Ground, ft above sea level (median)

Bins run from end A to end B of the line. “Most-named aquifer” is the family most often named on permits in the bin, with its count; permits naming no aquifer are the majority of the file and are not a family.

Reservoirs

Source DWR administrative record · verify at DWR structure records ↗

64 reservoir(s) with 38,800 storage measurement(s), 1950–2026. Basin storage as of 2025-10-31 (the record's own end — reservoir records publish ~annually): 60,965 AF across 28 reservoir(s).

Why storage matters to the flow network

Storage change is real water the mass balance must credit — a losing reach beside a filling reservoir isn't losing water, it's banking it.

Reservoir map — how full is each vessel?

What “full” is measured against

Bubble size is proportional to a reservoir's record-high storage. Fill is its last recorded storage as a share of its surveyed capacity (USACE National Inventory of Dams) where a confident NID match exists — the tooltip names the matched dam — and as a share of its own record high otherwise. A wrong capacity would be worse than an honest record high, so only confident joins upgrade.

A dashed teal ring marks reservoirs reporting live DWR telemetry: their fill reflects yesterday's storage, is drawn as a dotted tail on charts, and is treated as provisional until the next verified HydroBase snapshot supersedes it.

A dashed red ring marks a dam under an active storage restriction from DWR's Dam Safety branch — the State Engineer has limited how much it may legally store, so a low fill can be an order, not a drought. Hazard class and inspection condition come from the same record, joined only where the dam carries this reservoir's WDID or a confident NID match — a wrong dam's restriction would be worse than none shown.

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.

Reservoir	Last recorded storage (AF)	As of	Full	Dam (DWR Dam Safety)
▸ GROSS RES (0604199)	22,774	2025-10-31	—	—	dossier →
▸ BECKY RES NO 1 (0604272)	11,468	1980-06-30	—	—	dossier →
▸ HILLCREST/LEGGETT/VALMONT RESERVOIR COMPLEX (0604275)	9,117	2025-10-31	—	—	dossier →
▸ 0604515	8,816	2012-10-31	—	—	dossier →
▸ BARKER MEADOW RES (0604172)	7,180	2025-10-31	—	—	dossier →
▸ VALMONT LAKE RES (0604230)	7,150	2013-10-31	—	—	dossier →
▸ MARSHALL LAKE (0604212)	5,209	2025-10-31	—	—	dossier →
▸ BASELINE RES (0604173)	3,882	2025-10-31	—	—	dossier →

Snow and runoff

Source Independent agency measurement · fetched 2026-10-16 · verify at NRCS report generator ↗ Source Our computation, scored against a reference · NRCS forecast, graded here against the gage record

Snow-water equivalent, WY2027

A trace of snow at 2 of 3 sites (1.4 in of water at most); the median for the date is zero, so there is no percent to show yet. The snow year begins in October. The new water year began October 1; the chart fills in a day at a time as NRCS publishes each reading.

SNOTEL site	Elev (ft)	SWE (in)	% of median	Typical peak
Lake Eldora	9700	1.4	—	April 9 (14.0 in)
Niwot	9940	0.2	—	April 19 (15.0 in)
University Camp	10330	0.0	—	May 7 (19.9 in)

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.

Two ways a snow year goes wrong (1979–2026)

A bad snow year here comes in two flavors (both called snow drought), and the river feels them differently. In 8 of the last 48 winters the snow never came — the pack peaked below 80% of its median. In 1 more, the snow came but left early — a near-normal peak melted out two weeks or more ahead of its usual date, sending the water down before the season needed it.

The snow never came: 1981, 1985, 1991, 2001, 2002, 2004, 2012, 2026. The snow left early: 2006.

Computed by this site from 3 SNOTEL sites’ full daily records (NRCS AWDB, back to 1979). Each year is measured against each site’s own multi-decade median — not the 1991–2020 normal the chart above uses — so the 1980s grade against a fair baseline. Peak and melt-out need 85% of the season’s days on the record; thin years are dropped, not guessed. Derived from snow measurements alone — it cannot tell dry-from-warm causes apart, only what the snowpack did.

Runoff outlook — Boulder Ck nr Orodell

NRCS's final issue (2026-06-01) calls it even odds that at least 28 kAF arrives over 06-01 to 09-30 — 62% of a normal season; almost certainly at least 23, probably not more than 34. Our own record at this gage shows 11 kAF actually delivered. New forecasts begin in January. How to read these numbers →

The record-adjusted April benchmark

NRCS’s April issue (2026-04-01) called even odds at 44 kAF over 04-01 to 09-30. Re-anchoring that number on this river’s own history — how its April issues have verified, the winter’s baseflow, and the district’s April 1 snowpack — moves it to 23 kAF. The river delivered 17 kAF.

Computed by this site — not an NRCS number, and shown only because it earned it: replayed over 96 past seasons here (1962–2026), never seeing the year it predicts, the adjustment cut the typical April miss from 26% to 20%. At points where it does not beat NRCS, no adjusted number appears. Coefficients are frozen each August; the model never changes mid-season. Method and honest limits →

90% chance of at least	70% chance of at least	50% chance of at least	30% chance of at least	10% chance of at least	Normal	Observed
23	26	28	30	34	45	11

How good are these forecasts here? (1950–2025)

Grading every April issue against what the river then delivered, measured at this gage’s own record — 75 seasons: the median miss of the 50% forecast is 28%, with a high bias of 5%, and the observed volume landed inside the stated 10–90% band 56% 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 →

What April snow has meant for this river (1979–2026)

Across 48 measured years, the season’s water has loosely followed the April snowpack: a year opening April with 80% of median snow has typically gone on to deliver about 61% of a normal season (a snow-to-runoff elasticity of 0.7). In warm, early-melt years the river delivered a median of 65% of a normal season, against 76% in typical years — the timing of the melt matters, not just its size.

Computed by this site: the district’s April 1 SWE (% of each SNOTEL site’s own-record median) against the observed April–July volume at this gage (% of its median season) — a fixed window every year, unlike the forecast grades above, which use each issue’s own period. The slope is fit so single wild years can’t steer it (Theil–Sen, log space); years missing 10% of their days are dropped.

Runoff outlook — South Boulder Ck nr Eldorado Springs

NRCS's final issue (2026-06-01) calls it even odds that at least 15 kAF arrives over 06-01 to 09-30 — 56% of a normal season; almost certainly at least 9, probably not more than 19. New forecasts begin in January. How to read these numbers →

The record-adjusted April benchmark

NRCS’s April issue (2026-04-01) called even odds at 23 kAF over 04-01 to 07-31. Re-anchoring that number on this river’s own history — how its April issues have verified, the winter’s baseflow, and the district’s April 1 snowpack — moves it to 12 kAF. The river delivered 11 kAF.

Computed by this site — not an NRCS number, and shown only because it earned it: replayed over 66 past seasons here (1983–2026), never seeing the year it predicts, the adjustment cut the typical April miss from 21% to 21%. At points where it does not beat NRCS, no adjusted number appears. Coefficients are frozen each August; the model never changes mid-season. Method and honest limits →

90% chance of at least	70% chance of at least	50% chance of at least	30% chance of at least	10% chance of at least	Normal
9	12	15	16	19	27

Drought

Source Our computation, no independent reference · computed here from the screened DWR record Source Independent agency measurement · fetched 2026-10-13 · verify at U.S. Drought Monitor ↗

Right now

This is the 5th-driest week 39 in 128 years of record at SOUTH BOULDER CREEK NEAR ELDORADO SPRINGS, CO. (as of 2026-09-21; this week’s flow sits at the 4th percentile for the date). On this week’s US Drought Monitor, Boulder County is 24% in D4 exceptional drought (2026-10-13). The law agrees: the most senior active call leaves 99% of this district’s decreed flow rights junior to the calling right this week.

Every year since 1896, week by week

Each thin row is a year at SOUTH BOULDER CREEK NEAR ELDORADO SPRINGS, 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 19.1 percentile points; next closest 2012 (20.9), 1910 (22.3)). 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 Boulder, Gilpin, Jefferson, 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 2004 — 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 (2219 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.

1571–1999: this river before anyone measured it

Tree rings record wet and dry years centuries before the first gage. This is the published reconstruction of annual flow at Boulder Creek at Orodell — 429 years, with its uncertainty band drawn, not implied. A reconstruction is an estimate, not a measurement: it answers “is this decade unusual in four centuries?”, and nothing in this site’s statistics uses it.

Woodhouse, C.A. and J.J. Lukas (2006), Multi-century tree-ring reconstructions of Colorado streamflow for water resource planning, Climatic Change 78; data via NOAA NCEI World Data Service for Paleoclimatology / TreeFlow. Source data ↗

This basin’s droughts, by its own record

Drought	Span	Weeks	Trough percentile	Flows recovered	Water table back
unnamed dry spell	2024-12-02 → 2025-04-21	20	26th (2024-12-30)	42 weeks	—
the 2020-22 drought	2023-03-13 → 2023-11-06	34	17th (2023-06-05)	21 weeks	—
the 2020-22 drought	2020-08-24 → 2022-10-24	113	15th (2021-12-20)	75 weeks	—
the 2018 drought	2018-07-16 → 2019-04-08	38	17th (2018-10-15)	260 weeks	—
the 2012-13 drought	2012-08-27 → 2013-08-05	49	21st (2012-10-08)	8 weeks	—
the 2002 drought	2002-06-17 → 2003-02-17	35	9th (2002-09-02)	8 weeks	—
the 2002 drought	2000-11-27 → 2001-10-22	47	15th (2001-04-23)	12 weeks	—
unnamed dry spell	1994-10-24 → 1995-08-14	42	21st (1994-11-28)	0 weeks	—
unnamed dry spell	1989-10-16 → 1990-04-23	27	20th (1989-12-25)	0 weeks	—
unnamed dry spell	1988-10-31 → 1989-05-01	26	21st (1988-12-12)	51 weeks	—
the 1981 drought	1981-03-23 → 1982-03-15	51	16th (1981-08-03)	18 weeks	not yet (15 of 30 wells still below)
unnamed dry spell	1966-07-04 → 1967-04-10	40	18th (1966-08-29)	29 weeks	—
the 1963-64 drought	1964-06-22 → 1965-08-16	60	16th (1965-02-22)	0 weeks	—
the 1963-64 drought	1963-06-03 → 1963-11-18	24	12th (1963-07-29)	5 weeks	—

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 $38,555,719 in drought-caused claims across Boulder, Gilpin, Jefferson, Weld counties — 16.7% of all insured crop losses there. The worst year was 2022 ($8,809,218).

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 (2,104 rights across 129 years of shared record), colored by that year’s wetness from the barcode above. Here the correlation is +0.02 — 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.

Legal

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 ↗

27 systems touch this district (27 community systems reporting 619,582 people served, a figure that counts a wholesaler's customers twice); 2 of them carry an open health-based violation on EPA's record.

System	Serves	Source	Here
ARVADA CITY OF	171,610	Surface water	3% of its area
BOULDER CITY OF	166,080	Surface water	91% of its area
BROOMFIELD CITY AND COUNTY OF	106,153	Surface water	38% of its area
ERIE TOWN OF	47,444	Surface water	92% of its area
LAFAYETTE CITY OF	28,700	Surface water	100% of its area
FIRESTONE TOWN OF	27,798	Purchased surface water	10% of its area
LOUISVILLE CITY OF	20,975	Surface water	100% of its area
LEFT HAND WD	20,280	Surface water	40% of its area

and 19 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 ↗

36 reaches over 234.7 miles and 14 natural lake levels, held by the Colorado Water Conservation Board so that water stays in the stream. Every reach, with its schedule and case →

Boulder Creek, 16.5 mi: 0.643 (5/1 - 9/30) cfs (appropriated 1862, 90CW0193) · dossier
Boulder Creek, 16.5 mi: 0.5 (1/1 - 12/31) cfs (appropriated 1928, 90CW0193)
Boulder Creek, 16.5 mi: 0.451 (5/1 - 10/15) cfs (appropriated 1859, 90CW0193) · dossier
Boulder Creek, 16.5 mi: 1.5 (11/1 - 4/30) cfs (appropriated 1904, 90CW0193) · dossier
Boulder Creek, 16.5 mi: 1.07 (5/1 - 5/31), 2.23 (6/1 - 6/30), 2.16 (7/1 - 7/31), 1.62 (8/1 - 8/31), 1.23 (9/1 - 9/30) cfs (appropriated 1860, 90CW0193) · dossier
Boulder Creek, 16.5 mi: 1.8 (5/1 - 9/30) cfs (appropriated 1862, 90CW0193) · dossier

and 44 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 1859-10-01 to 2022-04-06. Of the 20 structures with a yield estimate, the median one’s senior right was in priority 100% of a median irrigation season and 47% in a dry one. 25 abandonment screens and 30 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: 2727 across 1867 structure(s); 201 structure(s) carry 897 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 call, calls set, seniority of the controlling call) are moving toward more administration, none the other way.

The three measures, year by year

One row per whole calendar year inside the call record's coverage (75 years); partly-covered years are omitted rather than reported as quiet. Trend is Mann-Kendall with the same significance gate as every other trend on this site. Counted from DWR's published call record, which begins in the early 2000s: earlier years are absent, not quiet. A rise in the number of calls set can also reflect how finely an administrator records one episode, which is why days under call -- insensitive to that -- is the component to read first. Advisory summary of the public record, not an administrative finding.

Year	Days under call	Calls set	Controlling priority (median)
2014	309	220	1873-06-30
2015	329	145	1870-06-01
2016	366	169	1875-06-30
2017	355	246	1881-02-01
2018	365	266	1876-05-10
2019	365	266	1881-02-01
2020	366	213	1869-04-01
2021	349	235	1867-04-15
2022	365	306	1867-04-15
2023	347	282	1869-06-01
2024	366	250	1881-02-01
2025	365	385	1875-03-10

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 67% in the 1950s to 78% in the 2020s.

The decades, and how the attribution works

Every structure's recorded diversions, attributed to what its water was decreed FOR in that year. Colorado decrees are usually multi-use (“IRR MUN COM IND…”), so these are shares of water whose decree includes a use — non-exclusive, and they do not sum to 100%. A right that adds municipal use in 1988 counts toward it only after. Decades before this basin's modern reporting era are flagged: their records are thinner, not their rivers drier. Shares of recorded diverted volume, not of water rights or of acreage. A structure's water is attributed only to uses decreed by that year, so a later municipal decree cannot reach back and recolour earlier diversions. Families overlap -- a ditch decreed for irrigation and municipal supply counts in both -- so shares can sum past 100%. Volume the record cannot attribute is reported separately, never distributed.

Decade	Recorded AF	Structures	Includes municipal	Unattributed
1950s	2,191,222	65	67%	54%
1960s	2,120,777	64	66%	52%
1970s	1,862,179	93	78%	11%
1980s	2,351,193	100	82%	6%
1990s	2,744,926	84	82%	2%
2000s	2,858,143	111	83%	2%
2010s	3,389,624	125	71%	13%
2020s	1,618,765	114	78%	19%

Why diversions stopped — call-based explanations

Sustained diversion stops matched to senior administrative calls.

BOULDER LEFT HAND DITCH (0600513) DWR↗ stopped 2025-09-25 (36+ days) — call at CLEAR CR PLATTE RIVER D curtailing 100% of its decreed rate [heuristic-strong, district-confirmed]
LEGGETT DITCH (0600537) DWR↗ stopped 2025-09-17 (44+ days) — call at CLEAR CR PLATTE RIVER D curtailing 100% of its decreed rate [heuristic-strong, district-confirmed]
FARMERS DITCH (0600525) DWR↗ stopped 2025-09-08 (18+ days) — call at JONES DONNELLY DITCH curtailing 100% of its decreed rate [heuristic-strong, district-confirmed]
MCCARTY DITCH (0600542) DWR↗ stopped 2025-08-27 (8+ days) — call at JONES DONNELLY DITCH curtailing 100% of its decreed rate [heuristic-strong, district-confirmed]
SMITH EMMONS DITCH (0600553) DWR↗ stopped 2025-08-18 (6+ days) — call at RURAL DITCH curtailing 100% of its decreed rate [heuristic-strong, district-confirmed]
HIGHLAND SOUTH SIDE DITCH (0600532) DWR↗ stopped 2025-08-15 (9+ days) — call at JONES DONNELLY DITCH curtailing 100% of its decreed rate [heuristic-strong, district-confirmed]
LEYNER COTTONWOOD DITCH (0600565) DWR↗ stopped 2025-08-15 (25+ days) — call at JONES DONNELLY DITCH curtailing 100% of its decreed rate [heuristic-partial, district-confirmed]
DRY CREEK DAVIDSON DITCH (0600569) DWR↗ stopped 2025-07-29 (19+ days) — call at JONES DONNELLY DITCH curtailing 100% of its decreed rate [heuristic-strong, district-confirmed]
MCCARTY DITCH (0600542) DWR↗ stopped 2025-07-17 (6+ days) — call at WARD DITCH curtailing 100% of its decreed rate [heuristic-strong]
LEYNER COTTONWOOD DITCH (0600565) DWR↗ stopped 2025-07-13 (14+ days) — call at EAST BOULDER DITCH curtailing 100% of its decreed rate [heuristic-partial, district-confirmed]
COMMUNITY DITCH (0600564) DWR↗ stopped 2025-05-15 (13+ days) — call at EAST BOULDER DITCH curtailing 99% of its decreed rate [heuristic-partial, district-confirmed]
COMMUNITY DITCH (0600564) DWR↗ stopped 2025-04-25 (5+ days) — call at BIJOU CANAL curtailing 87% 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.

Structure	Senior priority	Senior right: median / dry yr	Junior right: median / dry yr
LEGGETT-VALMONT INLET D (0600893) DWR↗	1864-05-01	100.0% / 38.3%	5.1% / 0.0%
KINNEAR DITCH (0600913) DWR↗	1872-05-20	61.2% / 13.6%	10.7% / 0.0%
COMMUNITY DITCH (0600564) DWR↗	1859-10-01	100.0% / 100.0%	5.1% / 0.0%
BOULDER WHITE ROCK DITCH (0600516) DWR↗	1862-06-01	100.0% / 43.5%	8.4% / 0.0%
KINNEAR DITCH NO 2 (0600614) DWR↗	1872-05-20	61.2% / 13.6%	14.5% / 0.0%
NEW DRY CR CARRIER DITCH (0600902) DWR↗	1859-10-01	100.0% / 100.0%	5.1% / 0.0%
S BOULDER DIVR CONDUIT (0600590) DWR↗	1930-01-01	10.7% / 0.0%	10.7% / 0.0%
0600502 DWR↗	1922-11-10	6.1% / 0.0%	6.1% / 0.0%
EAST BOULDER DITCH (0600575) DWR↗	1860-05-01	100.0% / 91.1%	10.7% / 0.0%
LOWER BOULDER DITCH (0600538) DWR↗	1859-10-01	100.0% / 100.0%	5.1% / 0.0%
DENVER POWER CONDUIT 1 (0600568) DWR↗	1945-05-10	8.4% / 0.0%	8.4% / 0.0%
GOODHUE DITCH (0600650) DWR↗	1859-10-01	100.0% / 100.0%	5.1% / 0.0%

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 ~1950 — idleness that begins before then may be unreported use, not nonuse (flagged † below).

WELLMAN DITCH (0600557) DWR↗ (1917-03-08, 120.0 cfs decreed): last active 1953 — 72 years idle
0600530 DWR↗ (1862-06-01, 1.8 cfs decreed): last active 1974 — 51 years idle
0604244 DWR↗ (1872-04-01, 0.0 cfs decreed): last active 1979 — 46 years idle
0604245 DWR↗ (1876-04-01, 0.0 cfs decreed): last active 1979 — 46 years idle
MARFELL LAKE NO 1 (0604210) DWR↗ (1880-04-01, 0.0 cfs decreed): last active 1980 — 45 years idle
MARFELL LAKE NO 2 (0604211) DWR↗ (1884-04-01, 0.0 cfs decreed): last active 1980 — 45 years idle
BECKY RES NO 1 (0604272) DWR↗ (1963-01-22, 0.0 cfs decreed): last active 1980 — 45 years idle
GREEN LAKE RES NO 2 (0604253) DWR↗ (1906-10-02, 0.0 cfs decreed): last active 1985 — 40 years idle
KINNEAR DITCH NO 2 (0600614) DWR↗ (1872-05-20, 781.0 cfs decreed): last active 1989 — 36 years idle
0604249 DWR↗ (1896-02-15, 0.0 cfs decreed): last active 1989 — 36 years idle

Compliance screens (30 advisory flags)

Screened 85 of 1867 structures with rights (158 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.

BARKER MEADOW RES (0604172) DWR↗: Observed p99 daily rate 233.0 cfs (max 709.0) exceeds total decreed absolute 0.2 cfs across 18966 recorded day(s).
MARSHALL LAKE (0604212) DWR↗: Observed p99 daily rate 101.8 cfs (max 210.0) exceeds total decreed absolute 2.1 cfs across 14518 recorded day(s).
BOULDER CR MIN FLOW C (0602100) DWR↗: Observed p99 daily rate 28.1 cfs (max 612.0) exceeds total decreed absolute 16.0 cfs across 33719 recorded day(s).
DRY CREEK NO 2 DITCH (0600570) DWR↗: Observed p99 daily rate 22.0 cfs (max 35.0) exceeds total decreed absolute 19.5 cfs across 13920 recorded day(s).
DRY CREEK DAVIDSON DITCH (0600569) DWR↗: Observed p99 daily rate 17.0 cfs (max 25.7) exceeds total decreed absolute 16.7 cfs across 13304 recorded day(s).
HOWARD DITCH (0600580) DWR↗: Observed p99 daily rate 17.0 cfs (max 32.0) exceeds total decreed absolute 12.1 cfs across 38102 recorded day(s).
MCGINN DITCH (0600586) DWR↗: Observed p99 daily rate 17.0 cfs (max 30.0) exceeds total decreed absolute 10.9 cfs across 24697 recorded day(s).
GOOSE HAVEN RESERVOIR COMPLEX (0603998) DWR↗: Observed p99 daily rate 16.6 cfs (max 46.0) exceeds total decreed absolute 1.7 cfs across 12516 recorded day(s).
BULL HEAD GULCH IRR SYS (0600584) DWR↗: Observed p99 daily rate 16.3 cfs (max 17.1) exceeds total decreed absolute 4.3 cfs across 206 recorded day(s).
JONES DONNELLY DITCH (0600582) DWR↗: Observed p99 daily rate 10.0 cfs (max 27.0) exceeds total decreed absolute 9.1 cfs across 24780 recorded day(s).

Seniority (top structures by decreed rate)

Structure	Senior priority date	Rights	Decreed abs (cfs)	Conditional?
LEGGETT-VALMONT INLET D (0600893) DWR↗	1864-05-01	9	2000.0	—
KINNEAR DITCH (0600913) DWR↗	1872-05-20	4	1644.9	—
COMMUNITY DITCH (0600564) DWR↗	1859-10-01	46	1291.8	yes
BOULDER WHITE ROCK DITCH (0600516) DWR↗	1862-06-01	9	909.1	—
KINNEAR DITCH NO 2 (0600614) DWR↗	1872-05-20	4	781.0	—
NEW DRY CR CARRIER DITCH (0600902) DWR↗	1859-10-01	24	680.0	—
S BOULDER DIVR CONDUIT (0600590) DWR↗	1930-01-01	1	461.0	yes
0600502 DWR↗	1922-11-10	1	430.0	—
EAST BOULDER DITCH (0600575) DWR↗	1860-05-01	13	405.0	—
LOWER BOULDER DITCH (0600538) DWR↗	1859-10-01	26	351.4	yes
DENVER POWER CONDUIT 1 (0600568) DWR↗	1945-05-10	1	344.0	yes
GOODHUE DITCH (0600650) DWR↗	1859-10-01	36	321.3	—
SOUTH BOULDER CANON DITCH (0600593) DWR↗	1859-10-01	22	258.4	—
DAVIDSON DITCH (0600567) DWR↗	1859-10-01	23	223.2	—
LAST CHANCE DITCH (0600615) DWR↗	1862-05-01	13	217.1	—

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)

20 applications in the 2026-09 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 2026-11-30 (45 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.

All 20 filings, with excerpts

Case	What it asks	County	Excerpt
`19CW3169`	reasonable diligence	—	Case No. 19CW3169 Court: Water Court, Division 1. Remark: Finding of reasonable diligence for Applicant’s divided 1/8th interest in the conditional rights for the Grey Mountain Dam & Reservoir decreed in the Original Decree. 3. Other Relevant Decree : Date of …
`2026CW10`	reasonable diligence	REASONABLE DILIGENCE IN DOUGLAS	CASE NUMBER 2026CW10 JOHN AND LINDSEY ROMINSKY, 1350 Cathedral Rock Dr., Sedalia, CO 80135. APPLICATION FOR FINDING OF REASONABLE DILIGENCE IN DOUGLAS COUNTY. Date of original decree: 12 -15-13 in case 10CW209, WD 1. Subsequent Decree: 09-04-20 in case 19CW36,…
`2026CW11`	reasonable diligence	—	CASE NUMBER 2026CW11 APPLICATION FOR FINDING OF REASONABLE DILIGENCE OF JOHN HARDEN – Application incomplete -no physical legal description for structures provided. Publication of Resume for 2026CW11 to be included in future resume once amended application is …
`2026CW3143`	—	—	CASE NUMBER 2026CW3143 (20CW3036, 13CW3099, 07CW75, 00CW212, 94CW26, 86CW372)…
`2026CW3144`	reasonable diligence	NORTH WELD	CASE NUMBER 2026CW3144 (17CW3057) Name of Applicant: NORTH WELD COUNTY WATER DISTRICT (“North Weld”) c/o Eric Reckentine, General Manager 32825 Co. Rd. 39 Lucerne, CO 80646 Phone: (970) 356 -3020 Direct all pleadings to: Scott E. Holwick, Esq. sholwick@lyonsga…
`2026CW3145`	reasonable diligence	SOUTH	CASE NUMBER 2026CW3145 Applicants. JASON MENEGATTI AND EMILY MENEGATTI, 645 South County Road 31, Berthoud, CO 80513 with all correspondence connected herewith being sent to Applicant’s counsel, David P. Jones, Lawrence Custer Grasmick Jones & Donovan, LLP., 5…
`2026CW3146`	reasonable diligence	—	CASE NUMBER 2026CW3146 (19CW3229, 13CW3028, 96CW199, 89CW212) TOWN OF CASTLE ROCK, Attn: Mark Marlowe, Director of Castle Rock Water 175 Kellogg Court Castle Rock, CO 80109 (720)733-6001. Serve all pleadings on: Madoline Wallace-Gross, Casey J. Weaver, Lyons G…
`2026CW3147`	plan for augmentation	PASO	CASE NUMBER 2026CW3147 APPLICATION FOR ADJUDICATION OF DENVER BASIN GROUNDWATER AND PLAN FOR AUGMENTATION OF DOLLEY LIVING TRUST IN EL PASO COUNTY – Order granting motion to request no publication order by Division 1 entered September 30, 2026. Water Division …
`2026CW3148`	—	—	CASE NUMBER 2026CW3148 NORTHERN COLORADO WATER CONSERVANCY DISTRICT, c/o Nathan Baker; 220 Water Avenue, Berthoud, Colorado 80513; nbaker@northernwater.org; (800) 369- 7246; Please direct all pleadings and correspondence to Applicants counsel: Michael A. Kopp,…
`2026CW3149`	reasonable diligence, make absolute	—	CASE NUMBER 2026CW3149 LOGAN WELL USERS, INC., P.O. Box 1172, Sterling Colorado, 80751, Lawrence Custer Grasmick Jones & Donovan LLP Ryan M. Donovan, #44435 and Regan M. O’Donnell, #62937 Attorneys for Applicant, Logan Well Users Inc. APPLICATION TO MAKE CONDI…
`2026CW3150`	reasonable diligence	EAST LARIMER	CASE NUMBER 2026CW3150 EAST LARIMER COUNTY WATER DISTRICT , 232 South Link Lane, Fort Collins, CO 80524. Lawrence Custer Grasmick Jones & Donovan LLP, Ryan M. Donovan, #44435. David L. Strait, #52659, Attorneys for Applicant, East Larimer County Water District…
`2026CW3151`	reasonable diligence	—	CASE NUMBER 2026CW3151 THE CACHE LA POUDRE WATER USERS ASSOCIATION , c/o Shawn Hoff, President, 106 Elm St., Eaton, Colorado 80615. Please send all further pleadings to: Brent A. Bartlett and Whitney Phillips, Fischer, Brown, Bartlett, Larsen & Irby, P.C., 131…
`2026CW3152`	plan for augmentation	—	CASE NUMBER 2026CW3152 DAVID D. CURRIN, 17945 Saddlewood Road, Monument, CO 80132; Please direct all correspondence concerning this application to: Chris D. Cummins, Monson, Cummins, Shohet & Farr, LLC, 13511 Northgate Estates Drive, Suite 250, Colorado Spring…
`2026CW3153`	new underground right	—	CASE NUMBER 2026CW3153 KIMBERLY KILZER AND MARCUS ELLER, 655 Hier Lane, Castle Rock, CO 80109. 720 -737-6252, kimberlykilzer@hotmail.com; ch4marcus@gmail.com. Forward all pleadings and correspondence to: Michael A. Kopp, #43204 and Erin Kincaid, # 61571. TROUT…
`2026CW3154`	reasonable diligence	NAL WATER RIGHT IN CLEAR CREEK	CASE NUMBER 2026CW3154 (20CW3007; 12CW218; 03CW142; 95CW155) CONCERNING THE APPLICATION FOR WATER RIGHTS OF PUBLIC SERVICE COMPANY OF COLORADO, A COLORADO CORPORATION. APPLICATION FOR FINDING OF REASONABLE DILIGENCE FOR A CONDITIONAL WATER RIGHT IN CLEAR CREEK…
`2026CW3155`	reasonable diligence	AL WATER RIGHTS IN CLEAR CREEK	CASE NUMBER 2026CW3155 (20CW3006; 12CW217; 06CW18; 98CW6; 91CW15; 91CW16) CONCERNING THE APPLICATION FOR WATER RIGHTS OF PUBLIC SERVICE COMPANY OF COLORADO, A COLORADO CORPORATION . APPLICATION FOR FINDING OF REASONABLE DILIGENCE FOR CONDITIONAL WATER RIGHTS I…
`2026CW3156`	new underground right	—	CASE NUMBER 2026CW3156 JUAN AND ELIZABETH AGUILAR, ET AL., 9166 E Rocky Mountain Lane, Parker, CO 80138. John D Buchanan, James J Petrock, Hayes Poznanovic Korver LLC, 700 17th Street, Suite 1800, Denver, CO 80202. APPLICATION FOR UNDERGROUND WATER RIGHTS IN T…
`2026CW3157`	plan for augmentation	—	CASE NUMBER 2026CW3157 THOMAS J. RIKLI AND MEREDITH A RIKLI, 6019 Alpine Vista Circle, Unit 208, Castle Rock, Colorado 80108; Please direct all pleadings and correspondence to Applicants’ counsel: Michael A. Kopp, Trevor I. Klein, Trout Raley, 1120 Lincoln St.…
`2026CW3158`	—	—	CASE NUMBER 2026CW3158 TINY TOWN INVESTMENT CORPORATION AND ADAM AND ANNA WOLKE, Tiny Town Investment Corporation, 6403 Boyd Court, Castle Rock, CO 80104; Adam and Anna Wolke, 5166 Bear Mountain Road, Evergreen, CO 80439 Broadway Street, Boulder, CO 80304; Ema…
`2026CW3160`	new underground right	—	CASE NUMBER 2026CW3160 ALPINE LAND RESOURCES LLC (“Alpine”), 970 Yuma St., Denver, CO 80204; Please direct all correspondence to: Wesley S. Knoll, Lawrence Custer Grasmick Jones & Donovan LLP, 5245 Ronald Reagan Blvd., Suite 1, Johnstown, CO 80534; wes@lcwater…

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.

Plan	Type	Status	Expires	Structure	Documents
FIRESTONE, TOWN OF	37-92-308(4) PLAN PENDING COURT APPLICATION	Approved	2026-03-31	—	plan file
GOOSE HAVEN RES #2	37-90-137(11) GRAVEL PIT PLAN	Approved	2026-07-31	0602537	plan file
JASPER RESERVOIR ISF LOAN	37-83-105(2)(a) Instream Flow Loan	Approved	2026-10-31	0602556	plan file
CITY OF BOULDER BRENTON BUILDING	37-92-308(5) PLANS LESS THAN 5 YEARS	Approved	2026-11-30	0602553	plan file
CITY OF LOUISVILLE 26CW3020	37-92-308(4) PLAN PENDING COURT APPLICATION	Approved	2027-05-31	—	plan file
TURNPIKE MINING RESOURCE	37-90-137(11) GRAVEL PIT PLAN	Approved	—	—	plan file
THREE LEAF FARM	37-92-308(4) PLAN PENDING COURT APPLICATION	Decreed	2026-03-31	—	plan file
TOWN OF FREDERICK	37-92-308(4) PLAN PENDING COURT APPLICATION	Decreed	—	—	plan file
ELDORADO ARTESIAN SPRINGS LBDC SHARES	37-92-308(4) PLAN PENDING COURT APPLICATION	Pending	—	0602509	plan file
FARFRUMWURKIN, LLLP-FILE PIT 112	37-90-137(11) GRAVEL PIT PLAN	Pending	—	—	plan file
CITY OF LOUISVILLE MUNICIPAL EFFLUENT	37-92-308(5) PLANS LESS THAN 5 YEARS	Finished Plan	2026-04-30	—	plan file

Water quality

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 2026-10-16 · verify at USGS current conditions ↗

1 USGS sensor reports temperature, conductance, dissolved oxygen or turbidity from inside this district; provisional readings, never merged into the verified record.

Site	Temp °C	Cond µS/cm	DO mg/L	Turb FNU	As of
SOUTH BOULDER CR AT FOREBAY NR ELDORADO SPRINGS CO ↗	7.8	59	9.9	2	2026-10-16 15:00

Where water has been sampled

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

The portal lists 2,809 sampling stations in this district's watershed (St. Vrain 10190005), of which 102 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 (60), Colorado River Watch (28), USGS Colorado Water Science Center (14). Most-sampled groups: Inorganics, Major, Metals, Physical, Nutrient, Inorganics, Minor, Metals. 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 ↗

27 community systems touch this district. 2 carry an open health-based violation on EPA's record. EPA sampled 9 of them for PFAS in 2023–25; none had PFOA or PFOS at or above the 2024 limit.

System	Serves	EPA record	PFAS (UCMR 5)	Lead, latest 90th pct
SANS SOUCI COOPERATIVE	150	3 open health-based	not sampled	0.0025 mg/L
MILE HI WATER INC HAULER	1,000	1 open health-based	not sampled	—
ARVADA CITY OF	171,610	2 of 12 quarters with a violation	none detected	0.0031 mg/L
BOULDER CITY OF	166,080	1 of 12 quarters with a violation	none detected	0.002 mg/L
BROOMFIELD CITY AND COUNTY OF	106,153	1 of 12 quarters with a violation	none detected	0.0025 mg/L
ERIE TOWN OF	47,444	clean, last 12 quarters	none detected	0.0026 mg/L
LAFAYETTE CITY OF	28,700	2 of 12 quarters with a violation	none detected	0.002 mg/L
FIRESTONE TOWN OF	27,798	clean, last 12 quarters	none detected	0.0036 mg/L
LOUISVILLE CITY OF	20,975	1 of 12 quarters with a violation	none detected	0.0 mg/L
LEFT HAND WD	20,280	clean, last 12 quarters	none detected	0.001 mg/L

and 17 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.

Every assessed stretch below is drawn on the district map above: turn on the Impaired waters layer (red is on the list, grey is assessed and attaining; click a stretch for its causes).

Water quality

24 of 31 assessed segments in this basin are on Colorado's impaired-waters list (2024 assessment), most often metals.

77% of assessed segments impaired

31 named segments assessed

Metals most common cause (22 segments)

2024 assessment cycle

Where these stretches are

Impaired, cleanup plan written (TMDL) Impaired, no plan yet Assessed, meeting standards

Tap a stretch for its causes. A named creek appears more than once because CDPHE assesses it in separate units, so the map shows where a finding starts and stops rather than colouring a whole creek at once.

On the impaired-waters list

Each entry is one CDPHE assessment unit — a named, mapped stretch of stream, not the whole creek at once, which is why a single named creek can appear more than once with different findings above and below a tributary or discharge.

Boulder Creek, mainstem MetalsPathogens Cleanup plan (TMDL)
Boulder Creek, mainstem AmmoniaMetalsPathogens Cleanup plan (TMDL)
Boulder Creek, mainstem AmmoniaMetalsPathogens Cleanup plan (TMDL)
Boulder Creek, mainstem AmmoniaMetalsPathogens Cleanup plan (TMDL)
Boulder Creek, mainstem and all tributaries MetalsPathogens
Boulder Creek, mainstem and tributaries. Metals
Coal Creek, mainstem
Coal Creek, mainstem Pathogens
Coal Creek, mainstem MetalsPathogens
Como Creek, mainstem and all tributaries Metals Cleanup plan (TMDL)
Fourmile Creek, mainstem and all tributaries Metals
Gamble Gulch MetalspH / acidity Cleanup plan (TMDL)
Gold Run Creek, mainstem and all tributaries. Metals
Middle Boulder Creek, all tributaries MetalsPathogens Cleanup plan (TMDL)
Middle Boulder Creek, mainstem Metals
Middle Boulder Creek, mainstem Metals Cleanup plan (TMDL)
Middle Boulder Creek, mainstem and all tributaries Metals Cleanup plan (TMDL)
North Boulder Creek, mainstem Metals Cleanup plan (TMDL)
North Boulder Creek, mainstem Metals Cleanup plan (TMDL)
North Boulder Creek, mainstem Metals Cleanup plan (TMDL)
Rock Creek. MetalsPathogens
South Boulder Creek, mainstem and all tributaries Metals Cleanup plan (TMDL)
South Boulder Creek, mainstem and all tributaries Metals
South Boulder Creek, mainstem and all tributaries Metals

5 segments meeting standards, 2 not yet assessed

Boulder Creek, all tributaries Fully Supporting
Boulder Creek, all tributaries Fully Supporting
Coal Creek, mainstem and all tributaries Fully Supporting
South Boulder Creek and Coal Creek, all tributaries Fully Supporting
South Boulder Creek, mainstem Fully Supporting
Cowdrey Drainage, mainstem Not Assessed
Cowdrey Drainage, mainstem Not Assessed

Source: EPA ATTAINS (Colorado Regulation 93 / Clean Water Act §303(d) list); state.co.us hosts the same assessment, ATTAINS is EPA's public mirror of it.. A segment being “Not Supporting” means it fails Colorado’s water-quality standard for the stated use (aquatic life, recreation, drinking-water supply...) for the stated cause — a legal, periodic finding, independent of whether any sensor happens to be deployed there right now.

Call cascade

If a call were placed at a given seniority, which structures in this basin would be out of priority, and how much of their decreed rate would be curtailed? Computed from this basin's cached decrees.

What this does and doesn't model. Seniority arithmetic only: every right junior to the call is treated as curtailed. It does not model reach applicability — structures downstream of the calling point are not administered by it — and it applies no futile-call judgment. Read it as “who is junior to this date, and by how much,” not as a prediction of what the Division Engineer would actually order.

Pick a calling right

Real decrees from this basin, ordered by administration number — that is, by actual seniority. The years will look out of order, and that is correct: an administration number encodes the adjudication date as well as the appropriation date, so a right appropriated in 1970 can be administered ahead of one from 1950. A senior call curtails almost everything; a junior one curtails almost nothing.

Or enter an administration number directly

Administration number

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

This week's diagnostic

Loading…

System status

Loading…

Active river calls

Loading…

Hydrographs vs. historical envelope

Loading…

Anomaly flags

Loading…

Snowpack — no snow on the ground at 3 SNOTEL sites — normal for the date; the snow year begins in October and typically peaks around April 9. Runoff outlook — Boulder Ck nr Orodell: even odds of at least 28 kAF over 06-01 to 09-30 — 62% of a normal season, per NRCS, issued 2026-06-01 — the season’s final; new forecasts begin in January. Runoff outlook — South Boulder Ck nr Eldorado Springs: even odds of at least 15 kAF over 06-01 to 09-30 — 56% of a normal season, per NRCS, issued 2026-06-01 — the season’s final; new forecasts begin in January. Full snow & runoff picture — charts, forecast history and how the forecasts have verified →

Sites, exceedance bands and sources

SNOTEL site	Elev (ft)	SWE (in)	% of median	Typical peak
Lake Eldora	9700	1.4	—	April 9 (14.0 in)
Niwot	9940	0.2	—	April 19 (15.0 in)
University Camp	10330	0.0	—	May 7 (19.9 in)

Boulder Ck nr Orodell — 06-01 to 09-30 volume, thousand acre-feet (chance the volume is AT LEAST this):

90%	70%	50%	30%	10%	Normal
23	26	28	30	34	45

South Boulder Ck nr Eldorado Springs — 06-01 to 09-30 volume, thousand acre-feet (chance the volume is AT LEAST this):

90%	70%	50%	30%	10%	Normal
9	12	15	16	19	27

Snow-water equivalent and medians (1991–2020) from NRCS SNOTEL; seasonal volume forecasts from the NRCS National Water and Climate Center. Sites and forecast points are assigned to the district whose boundary contains them — snowpack that feeds this district can also sit in a neighboring headwater district. Toggle the Snow chip on the map above to see the sites.

Topology cross-check: 0 parent disagreements, 6 sizable streams not on this network (vs DWR's route framework — under review)

This flow network was built mechanically; DWR's Source Water Route Framework disagrees with it in the places below. Each row is a question a human reviewer has not yet answered — not an error verdict. Checked 9 streams, 9 agree. Know this water? Tell us →

Sizable streams DWR maps here that this network does not carry:

Fourmile Creek (15 mi) · Bear Canyon Creek (8 mi) · Dry Creek (6 mi) · Bummers Gulch (4 mi) · Johnson Gulch (3 mi) · Bullhead Gulch (3 mi)

Something wrong on this page? Tell us →

Boulder Creek

Schematic

Historical

Evolution of the network

Trends

Gage flow trend & changepoints

How the measurement network itself changed

Mass-balance (network closure) trend

Reach gain/loss shifts (1950–2026)

Cross-gage pattern fingerprint

Structures most implicated by reconciliation (as of 2026-09-24)

Data provenance & quality

Groundwater

Well map

3D aquifer x-ray

Water-table trends

Stream corridors — the surface connection

Permits issued here, by year

What drillers reached, township by township

Reservoirs

Reservoir map — how full is each vessel?

Basin storage, end of each water year

Largest reservoirs on record

Snow and runoff

Snow-water equivalent, WY2027

Two ways a snow year goes wrong (1979–2026)

Runoff outlook — Boulder Ck nr Orodell

The record-adjusted April benchmark

How good are these forecasts here? (1950–2025)

What April snow has meant for this river (1979–2026)

Runoff outlook — South Boulder Ck nr Eldorado Springs

The record-adjusted April benchmark

Drought

Right now

Every year since 1896, week by week

This year against its analogs

The Drought Monitor’s view since 2000

The law’s own drought gauge

1571–1999: this river before anyone measured it

This basin’s droughts, by its own record

What drought has cost here

When this basin claimed its water

Legal

Who serves it, who protects it

Public water systems here

Instream-flow rights held by the state

Is the river getting harder to divert from?

What the water is for — decade by decade

Why diversions stopped — call-based explanations

Right yield — how often could these rights actually divert?

Abandonment radar (25 screens)

Compliance screens (30 advisory flags)

Seniority (top structures by decreed rate)

Recent inventory & legal-document changes

Water-court filings this month (division-wide)

Active substitute water supply plans in this district

Water quality

The water itself, in this district

Right now

Where water has been sampled

Drinking water

Water quality

Where these stretches are

On the impaired-waters list

Call cascade

Pick a calling right

This week's diagnostic

System status

Active river calls

Hydrographs vs. historical envelope

Anomaly flags

Keep track of Colorado’s water?