Hydrohistorian
Big Thompson River
Big Thompson River on the ground — the ditches, wells, reservoirs and gages of Water District 4 · 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.
The Big Thompson River is critically low for late September -- 24% of normal flow. 1 call stands against it right now; the most senior right calling dates to 1873. DWR's statements do not settle whether 6 more calls reach it. This year's runoff outlook, issued 2026-06-01, called for 61% of normal.
Schematic
Historical
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
This year, in context
In the weeks around 2026-09-27 (the newest reading on file), flows at the 46 ranked gages are running at a median 70% of their own long-term norm for this window — 32 below a typical year, 14 at or above. Driest relative to its record: BLOWER DITCH, ranking 1st lowest of 16 years.
How this comparison is made
Each gage's mean flow over the 3 days either side of 2026-09-27, compared with the same window in every year of its own record — so a gage is only ever measured against itself, and gages with no record in the window are counted out rather than guessed.
Gage flow trend & changepoints
What counts as a trend here
Computed 2026-10-11 19:46 from 72 gage(s) with cached period-of-record data. The series is each gage's annual mean flow in cfsCubic feet per second, a rate of flow. One cfs running for a day is about 2 acre-feet. (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 72 gages with enough record, 10 are trending down and 5 up, and 11 carry a detected shift. The clearest is Saint Vrain Supply Canal T.O. to L. Thompson River, its annual mean flow changing -1.86 cfs per decade (-40.1% of its median annual flow) over 43 years (p<0.0001). The other 56 show no clear signal either way.
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 |
|---|---|---|---|---|---|
|
▸
Saint Vrain Supply Canal T.O. to L. Thompson River SVSLT1CO |
↓ decreasing | -1.86 cfs -40.1% | p<0.001 | 43 | ~1966 |
|
▸
Big Thompson River Bl Powerhouse, near Drake BTBLOVCO |
↓ decreasing | -18.21 cfs -13.3% | p<0.001 | 63 | ~1953 |
|
▸
⚠️
Saint Vrain Supply Canal to Hertha Creek SVSHERCO |
↑ increasing | +0.17 cfs | p<0.001 | 43 | ~1983 |
|
▸
Big Thompson River at Mouth of Canyon near Drake BTCANYCO |
↓ decreasing | -15.56 cfs -15.9% | p<0.001 | 81 | ~1958 |
|
▸
Miner Longan Ditch MILDITCO |
↓ decreasing | -1.47 cfs -115.9% | p=0.003 | 14 | ~2017 |
|
▸
South Side Ditch SOSDITCO |
↓ decreasing | -1.55 cfs -37.5% | p=0.006 | 13 | — |
|
▸
Reorganized Farmers Ditch REODITCO |
↓ decreasing | -3.80 cfs -46.2% | p=0.012 | 14 | ~2017 |
|
▸
Charles Hansen Feeder Canal below Big Thompson Siphon HFCBBSCO |
↑ increasing | +4.94 cfs +3.1% | p=0.019 | 75 | — |
|
▸
Hill and Brush Ditch HIBDITCO |
↓ decreasing | -0.96 cfs -39.8% | p=0.023 | 15 | — |
|
▸
Dille Tunnel near Drake DILTUNCO |
↑ increasing | +2.90 cfs +11.7% | p=0.027 | 75 | ~1982 |
|
▸
Evanstown Ditch EVADITCO |
↓ decreasing | -5.51 cfs -54.1% | p=0.029 | 12 | — |
|
▸
USBR Power Plant at Big Thompson Canyon Mouth BTPPMCCO |
↓ decreasing | -17.34 cfs -21.4% | p=0.030 | 25 | ~2011 |
|
▸
Glacier Creek near Estes Park GLAESTCO |
↑ increasing | +6.62 cfs +21.6% | p=0.036 | 17 | — |
|
▸
Big Thompson River at Mouth near La Salle BIGLASCO |
↑ increasing | +3.53 cfs +5.4% | p=0.039 | 100 | ~1956 |
|
▸
Big Thompson River above Lake Estes BTABESCO |
↓ decreasing | -4.38 cfs -3.4% | p=0.044 | 75 | ~1965 |
|
▸
Big Thompson River below Lake Estes BTBLESCO |
no clear trend | -3.92 cfs -4.4% | p=0.273 | 96 | ~1953 |
⚠️ 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.
56 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. 51 gage(s) and 123 structure(s) report in 2026, but structure reporting only reached half its modern level around ~1994. 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) |
|---|---|---|
| 1910s | 1 | 0 |
| 1920s | 1 | 0 |
| 1930s | 4 | 0 |
| 1940s | 5 | 0 |
| 1950s | 19 | 38 |
| 1960s | 19 | 34 |
| 1970s | 15 | 37 |
| 1980s | 16 | 41 |
| 1990s | 22 | 64 |
| 2000s | 26 | 74 |
| 2010s | 48 | 74 |
| 2020s | 51 | 112 |
Mass-balance (network closure) trend
Structure divrec-history backfill coverage as of the last check: 5% of 1753 schematic-relevant structures. 0 year(s) clear the 30% coverage gate so far -- the trend activates automatically once qualifying years span a full decade. No action needed; the nightly backfill keeps extending the record.
Reach gain/loss shifts (1950–2026)
Mass-balance kinks computed for every summer month back to 1950 (5701 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.
- HANSEN FEEDER CANAL LOVELAND TURNOUT: reach shifted from -172 cfs to -21 cfs summer mean (more gaining, p=0.000, 26 yr) [alluvial valley: real alluvial aquifer -- a decades-long shift toward losing is the classic signature of alluvial pumping and urbanization]
- USBR POWER PLANT AT BIG THOMPSON CANYON MOUTH: reach shifted from +221 cfs to +117 cfs summer mean (more losing, p=0.006, 30 yr) [sedimentary plains/foothills: moderate groundwater connectivity -- gain/loss shifts can be real aquifer response; corroborate with nearby well records]
- MINER LONGAN DITCH: reach shifted from -143 cfs to -135 cfs summer mean (more gaining, p=0.043, 11 yr) [alluvial valley: real alluvial aquifer -- a decades-long shift toward losing is the classic signature of alluvial pumping and urbanization] [measurement-evolution caution: this shift co-moves with the growth of the gage/metering network (rho=0.82) -- part of it may be unaccounted water becoming accounted, not hydrologic change]
- RYANS GULCH EXCHANGE DITCH: reach shifted from -60 cfs to -17 cfs summer mean (more gaining, p=0.001, 17 yr) [sedimentary plains/foothills: moderate groundwater connectivity -- gain/loss shifts can be real aquifer response; corroborate with nearby well records]
- WIND RIVER NEAR ESTES PARK: reach shifted from +185 cfs to -41 cfs summer mean (more losing, p=0.009, 65 yr) [mountain crystalline canyon: 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=-0.54) -- part of it may be unaccounted water becoming accounted, not hydrologic change]
- BIG THOMPSON RIVER AT MOUTH OF CANYON NEAR DRAKE: reach shifted from +222 cfs to -61 cfs summer mean (more losing, p=0.000, 63 yr) [mountain crystalline canyon: 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=-0.52) -- part of it may be unaccounted water becoming accounted, not hydrologic change]
Groundwater now has its own tab: 91 monitored well(s), water-table trends, stream corridors, and the advisory depletion screen.
Reservoirs now has its own tab: 38 reservoir(s), end-of-year storage back to 1950, click-to-chart histories.
Cross-gage pattern fingerprint
Over the 80-year window with full coverage (1947–2026), the dominant shared pattern across 3 gage(s) explains 45% of year-to-year variance (almost certainly a basin-wide climate/snowpack driver).
BTBLESCO doesn't move with that shared pattern -- a real, localized signal (a new diversion, land-use change, or a gage-specific data problem) worth a closer look, not necessarily noise.
Structures most implicated by reconciliation (as of 2026-09-27)
Which structures' data absorbed the most correction when the current mass-balance snapshot was reconciled -- see the Historical tab for the full picture on any date.
- FT MORGAN OUTING CLUB PL (diversion): +7.4 cfs (20% of that reach's correction)
- ESTES PARK DITCH 1 (diversion): +7.4 cfs (20% of that reach's correction)
- LAKE ESTES (diversion): +7.4 cfs (20% of that reach's correction)
- ESTES PARK DITCH 4 (diversion): +7.4 cfs (20% of that reach's correction)
- OLYMPUS TUNNEL (diversion): +7.4 cfs (20% of that reach's correction)
- LARIMER CO SPRING E (return): -7.4 cfs (17% of that reach's correction)
- LARIMER CO SPRING F (return): -7.4 cfs (17% of that reach's correction)
- DILLE TUNNEL (diversion): -7.4 cfs (17% of that reach's correction)
- ARKINS SUPPLY CNL (diversion): -7.4 cfs (17% of that reach's correction)
- HANSEN FEEDER CNL PUMP (diversion): -7.4 cfs (17% of that reach's correction)
Data provenance & quality
Where these numbers come from and how far they can be trusted. Grade C (3/6 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 | stale | newest gage reading is 14 day(s) old (target 7) |
| diversion record | expected-lag | newest diversion record is 346 day(s) old (DWR publishes ~1 year in arrears) |
| structure coverage | sparse | 5% of schematic structures have data |
Independent check: PASS — 100.0000% agreement across 491,920 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: PASS — 99.70% day-level agreement with USGS's own published records for the same gages, across 19 co-listed station(s) and 179,779 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.
72 gage(s) / 800,703 daily values (1914-04-01–2026-09-27); 286 structure(s) with diversion records; 1296 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 ↗
6,963 water-level measurements across 91 monitored well(s) — 60 alluvial, 5 bedrock — plus 16 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 4 well(s) with enough record for a trend test: 4 declining, 0 rising.
| Fastest-declining wells | Setting | ft / decade | Span | p |
|---|---|---|---|---|
| ▸ LSP-040 DSS02MLK | alluvial | -1.85 | 22 yr | 0.0 |
| ▸ SB00406711DCC | alluvial | -1.53 | 41 yr | 0.0031 |
| ▸ SB00506816ABA | unknown | -0.79 | 38 yr | 0.0068 |
| ▸ SB00506817AAB | alluvial | -0.53 | 45 yr | 0.0017 |
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.
MINER LONGAN DITCH: 1 alluvial well(s) nearby. Glover screen: 0.0 cfs of nearby metered alluvial pumping → est. lagged depletion 0.0–0.0 cfs (uncalibrated T/S ranges; flagged for SPDSS calibration, AWAS cross-check, and expert review — DWR's AWAS is the authority).
RYANS GULCH EXCHANGE DITCH: 6 alluvial well(s) nearby. Glover screen: 0.2 cfs of nearby metered alluvial pumping → est. lagged depletion 0.1–0.2 cfs (uncalibrated T/S ranges; flagged for SPDSS calibration, AWAS cross-check, and expert review — DWR's AWAS is the authority).
WIND RIVER NEAR ESTES PARK: 0 alluvial well(s) nearby. Glover screen: 0.0 cfs of nearby metered alluvial pumping → est. lagged depletion 0.0–0.0 cfs (uncalibrated T/S ranges; flagged for SPDSS calibration, AWAS cross-check, and expert review — DWR's AWAS is the authority).
BIG THOMPSON RIVER BELOW HILLSBOROUGH DIVERSION: 6 alluvial well(s) nearby; pooled water table -2.2 ft (1941–1986, decreasing, p=0.0017)
BIG THOMPSON RIVER ABOVE LAKE ESTES: 0 alluvial well(s) nearby
BIG THOMPSON RIVER AT LOVELAND, CO.: 5 alluvial well(s) nearby. Glover screen: 0.0 cfs of nearby metered alluvial pumping → est. lagged depletion 0.0–0.0 cfs (uncalibrated T/S ranges; flagged for SPDSS calibration, AWAS cross-check, and expert review — DWR's AWAS is the authority).
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.
56% are constructed wells; 6% 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
5,771 located water-supply permits with an issue date, 1953 to 2026; half of them had been issued by 1993, and the busiest year was 1972 with 331. The district’s 1,543 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 9,421 above counts every permit on file here; 2,107 of them have no usable location or no issue date and are not in this chart.
water-supply permits issued that year monitoring holes, when shown
The counts by year, as a table
| Year | Issued | Monitoring holes | Water-supply | Issued through that year |
|---|---|---|---|---|
| 1953 | 9 | 0 | 9 | 9 |
| 1954 | 14 | 0 | 14 | 23 |
| 1955 | 24 | 0 | 24 | 47 |
| 1956 | 7 | 0 | 7 | 54 |
| 1957 | 10 | 0 | 10 | 64 |
| 1958 | 7 | 0 | 7 | 71 |
| 1959 | 21 | 0 | 21 | 92 |
| 1960 | 22 | 0 | 22 | 114 |
| 1961 | 17 | 0 | 17 | 131 |
| 1962 | 6 | 0 | 6 | 137 |
| 1963 | 11 | 0 | 11 | 148 |
| 1964 | 36 | 0 | 36 | 184 |
| 1965 | 15 | 0 | 15 | 199 |
| 1966 | 23 | 0 | 23 | 222 |
| 1967 | 7 | 0 | 7 | 229 |
| 1968 | 12 | 0 | 12 | 241 |
| 1969 | 24 | 0 | 24 | 265 |
| 1970 | 26 | 0 | 26 | 291 |
| 1971 | 41 | 0 | 41 | 332 |
| 1972 | 331 | 0 | 331 | 663 |
| 1973 | 116 | 0 | 116 | 779 |
| 1974 | 59 | 0 | 59 | 838 |
| 1975 | 54 | 0 | 54 | 892 |
| 1976 | 73 | 0 | 73 | 965 |
| 1977 | 144 | 0 | 144 | 1,109 |
| 1978 | 181 | 0 | 181 | 1,290 |
| 1979 | 163 | 0 | 163 | 1,453 |
| 1980 | 113 | 0 | 113 | 1,566 |
| 1981 | 112 | 2 | 110 | 1,678 |
| 1982 | 109 | 0 | 109 | 1,787 |
| 1983 | 133 | 0 | 133 | 1,920 |
| 1984 | 119 | 0 | 119 | 2,039 |
| 1985 | 136 | 25 | 111 | 2,175 |
| 1986 | 83 | 2 | 81 | 2,258 |
| 1987 | 89 | 8 | 81 | 2,347 |
| 1988 | 160 | 64 | 96 | 2,507 |
| 1989 | 118 | 27 | 91 | 2,625 |
| 1990 | 94 | 12 | 82 | 2,719 |
| 1991 | 167 | 37 | 130 | 2,886 |
| 1992 | 176 | 19 | 157 | 3,062 |
| 1993 | 194 | 38 | 156 | 3,256 |
| 1994 | 279 | 92 | 187 | 3,535 |
| 1995 | 206 | 24 | 182 | 3,741 |
| 1996 | 174 | 68 | 106 | 3,915 |
| 1997 | 168 | 36 | 132 | 4,083 |
| 1998 | 192 | 45 | 147 | 4,275 |
| 1999 | 180 | 64 | 116 | 4,455 |
| 2000 | 174 | 28 | 146 | 4,629 |
| 2001 | 126 | 20 | 106 | 4,755 |
| 2002 | 181 | 32 | 149 | 4,936 |
| 2003 | 153 | 31 | 122 | 5,089 |
| 2004 | 158 | 43 | 115 | 5,247 |
| 2005 | 124 | 32 | 92 | 5,371 |
| 2006 | 70 | 3 | 67 | 5,441 |
| 2007 | 83 | 11 | 72 | 5,524 |
| 2008 | 103 | 34 | 69 | 5,627 |
| 2009 | 70 | 26 | 44 | 5,697 |
| 2010 | 41 | 2 | 39 | 5,738 |
| 2011 | 51 | 15 | 36 | 5,789 |
| 2012 | 39 | 6 | 33 | 5,828 |
| 2013 | 70 | 17 | 53 | 5,898 |
| 2014 | 75 | 15 | 60 | 5,973 |
| 2015 | 73 | 16 | 57 | 6,046 |
| 2016 | 163 | 103 | 60 | 6,209 |
| 2017 | 106 | 33 | 73 | 6,315 |
| 2018 | 123 | 50 | 73 | 6,438 |
| 2019 | 71 | 20 | 51 | 6,509 |
| 2020 | 117 | 57 | 60 | 6,626 |
| 2021 | 150 | 77 | 73 | 6,776 |
| 2022 | 162 | 90 | 72 | 6,938 |
| 2023 | 78 | 35 | 43 | 7,016 |
| 2024 | 135 | 93 | 42 | 7,151 |
| 2025 | 114 | 74 | 40 | 7,265 |
| 2026 | 49 | 17 | 32 | 7,314 |
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
20 PLSS townships here where at least 5 water-supply permits naming the same aquifer filed a depth (5,195 permits in all). Each column is one township, six miles square, on one scale to 1,000 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. 9 of these townships straddle a district line and are filed here because most of their permits are.
701
461
418
358 · 91% here
341
338
329
274 · 68% here
266 · 82% here
263
253 · 58% here
253
222 · 94% here
210
149 · 92% here
112
77
71 · 94% here
55 · 51% here
44 · 75% here
unnamed alluvium fractured crystalline other named faint = where the permits naming it stopped (10th–90th pct) · solid = their screens · tick = median · ft below ground as filed
Every township here, as a table
| 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 |
|---|---|---|---|---|---|---|
| T5N R72W 6th PM | 99% | unnamed | 693 | 37 / 260 / 600 | 10 / 220 / 460 | 137 / 340 / 580 |
| T5N R72W 6th PM | 99% | fractured crystalline | 6 | 690 / 800 / 901 | — | — |
| T5N R70W 6th PM | 99% | unnamed | 456 | 44 / 240 / 600 | 30 / 190 / 460 | 79 / 340 / 600 |
| T6N R72W 6th PM | 99% | unnamed | 410 | 20 / 300 / 600 | 24 / 245 / 453 | 120 / 360 / 584 |
| T6N R72W 6th PM | 99% | fractured crystalline | 6 | 600 / 676 / 931 | — | — |
| T4N R71W 6th PM | 91% | unnamed | 355 | 96 / 400 / 680 | 18 / 210 / 508 | 168 / 400 / 660 |
| T6N R71W 6th PM | 99% | unnamed | 334 | 200 / 452 / 800 | 80 / 280 / 528 | 205 / 440 / 752 |
| T6N R71W 6th PM | 99% | fractured crystalline | 5 | 477 / 605 / 632 | — | — |
| T4N R70W 6th PM | 100% | unnamed | 333 | 146 / 345 / 658 | 75 / 220 / 500 | 180 / 358 / 600 |
| T5N R73W 6th PM | 99% | unnamed | 324 | 56 / 209 / 423 | 30 / 200 / 391 | 100 / 290 / 460 |
| T5N R73W 6th PM | 99% | fractured crystalline | 5 | 454 / 500 / 761 | — | — |
| T7N R70W 6th PM | 68% | unnamed | 272 | 200 / 440 / 700 | 50 / 305 / 540 | 240 / 440 / 682 |
| T4N R73W 6th PM | 82% | unnamed | 262 | 86 / 270 / 580 | 26 / 220 / 466 | 140 / 325 / 593 |
| T5N R69W 6th PM | 98% | unnamed | 251 | 16 / 37 / 240 | 10 / 24 / 152 | 20 / 47 / 278 |
| T5N R69W 6th PM | 98% | other named | 7 | 56 / 65 / 65 | 20 / 20 / 22 | 54 / 62 / 63 |
| T4N R67W 6th PM | 58% | unnamed | 233 | 21 / 34 / 60 | 6 / 19 / 39 | 23 / 36 / 58 |
| T4N R67W 6th PM | 58% | alluvium | 15 | 31 / 40 / 300 | 16 / 28 / 115 | 33 / 48 / 355 |
| T5N R71W 6th PM | 99% | unnamed | 251 | 30 / 285 / 700 | 20 / 275 / 562 | 50 / 380 / 700 |
| T6N R70W 6th PM | 94% | unnamed | 217 | 80 / 370 / 760 | 58 / 240 / 562 | 160 / 400 / 744 |
| T4N R72W 6th PM | 100% | unnamed | 205 | 15 / 340 / 600 | 11 / 265 / 520 | 156 / 392 / 598 |
| T7N R71W 6th PM | 92% | unnamed | 146 | 180 / 400 / 700 | 80 / 295 / 522 | 236 / 402 / 686 |
| T4N R69W 6th PM | 98% | unnamed | 110 | 30 / 80 / 305 | 10 / 30 / 270 | 42 / 99 / 410 |
| T5N R68W 6th PM | 96% | unnamed | 77 | 15 / 35 / 300 | 10 / 24 / 246 | 18 / 56 / 472 |
| T4N R68W 6th PM | 94% | unnamed | 70 | 27 / 48 / 300 | 9 / 34 / 260 | 29 / 48 / 416 |
| T5N R67W 6th PM | 51% | unnamed | 53 | 21 / 31 / 433 | 6 / 16 / 261 | 21 / 28 / 394 |
| T7N R72W 6th PM | 75% | unnamed | 39 | 200 / 325 / 561 | 88 / 200 / 428 | 200 / 310 / 488 |
| T7N R72W 6th PM | 75% | fractured crystalline | 5 | 299 / 600 / 647 | — | — |
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.
The ground each well hangs from is a 1-km elevation model sampled at the point the permit was spotted, so the profile is real topography smoothed to about a kilometre — peaks are shaved, valleys filled a little — and the depths are the driller’s, measured down from that ground.
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 ↗
38 reservoir(s) with 17,304 storage measurement(s), 1950–2026. Basin storage as of 2025-10-31 (the record's own end — reservoir records publish ~annually): 145,945 AF across 27 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) | |
|---|---|---|---|---|---|
| ▸ GLACIER RES NO 1 (0404111) | 63,966 | 1980-11-16 | — | — | dossier → |
| ▸ CARTER LAKE RES (0404513) | 62,809 | 2025-10-31 | — | — | dossier → |
| ▸ DEFRANCE RES (0404114) | 22,080 | 1951-11-01 | — | — | dossier → |
| ▸ BOYD LAKE RES (0404110) | 18,104 | 2025-10-31 | — | — | dossier → |
| ▸ BOULDER LARIMER RES (0404156) | 18,104 | 2025-10-31 | — | — | dossier → |
| ▸ LOVELAND GREELEY RES (0404131) | 11,540 | 2025-10-31 | — | — | dossier → |
| ▸ DRY CREEK RESERVOIR (0403721) | 8,912 | 2025-10-31 | — | — | dossier → |
| ▸ LOVELAND MUNICIPAL RES (0403659) | 6,772 | 2025-10-31 | — | — | dossier → |
Snow and runoff
Source Independent agency measurement · fetched 2026-10-12 · 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 2 sites (0.1 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) | Median (in) | % of median | Typical peak |
|---|---|---|---|---|---|
| Bear Lake | 9490 | 0.1 | 0.0 | — | April 27 (19.8 in) |
| Willow Park | 10710 | 0.1 | 0.0 | — | April 29 (21.0 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 (1981–2026)
A bad snow year here comes in two flavors (both called snow droughtA winter that shorts the snowpack. It happens two ways: a dry one, where the snow never comes, and a warm one, where near-normal snow falls but melts off weeks early -- and the river feels them differently.), and the river feels them differently. In 6 of the last 46 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: 1987, 1991, 1992, 2002, 2012, 2026. The snow left early: 1981.
Computed by this site from 2 SNOTEL sites’ full daily records (NRCS AWDB, back to 1981). 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 — Big Thompson R at Canyon Mouth
NRCS's final issue (2026-06-01) calls it even odds that at least 48 kAF arrives over 06-01 to 09-30 — 61% of a normal season; almost certainly at least 38, probably not more than 62. New forecasts begin in January. How to read these numbers →
| 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 |
|---|---|---|---|---|---|
| 38 | 43 | 48 | 53 | 62 | 79 |
How good are these forecasts here? (1951–2012)
Grading every April issue against what the river then delivered, measured at this gage’s own record — 61 seasons: the median miss of the 50% forecast is 78%, with a high bias of 78%, and the observed volume landed inside the stated 10–90% band 16% 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 (1981–2013)
Across 33 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 44% of a normal season (a snow-to-runoff elasticityHow strongly one number moves with another. A snow-to-runoff elasticity of 1.5 means a 10% shortfall in April snowpack has typically become a 15% shortfall in the season's water. of 1.2). In warm, early-melt years the river delivered a median of 41% of a normal season, against 70% 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.
Drought
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 24th-driest week 39 in 101 years of record at BIG THOMPSON RIVER AT MOUTH NEAR LA SALLE (as of 2026-09-21; this week’s flow sits at the 24th percentileRank against the record: a river at its 5th percentile is lower than it was in 95 of the past 100 years on this same date. for the date). On this week’s US Drought Monitor, Weld County is 7% in D4 exceptional drought (2026-10-06). The law agrees: the most senior active call leaves 100% of this district’s decreed flow rights junior to the calling right this week.
Every year since 1914, week by week
Each thin row is a year at BIG THOMPSON RIVER AT MOUTH NEAR LA SALLE; 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 12.9 percentile points; next closest 2008 (14.8), 2006 (15.7)). The analog’s remainder is drawn as context — its ending is what happened to it, not a forecast for this year.
The Drought Monitor’s view since 2000
Mean share of area in each class across Boulder, Larimer, 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 (2300 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.
1569–1999: 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 Big Thompson River at Canyon Mouth — 431 years, with its uncertainty band drawn, not implied — and the green line is the measured record at the same gage, water-year totals from DWR’s daily data, carrying the story through 2013. 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.
Why the two lines disagree on purpose: the trees were calibrated against naturalized flow — upstream diversions and storage added back — while the gage measures what the ditches left in the river. So the measured line running below the reconstruction is not an error; the gap is, roughly, human use. Over the 66 years both series cover, the river carried a median of 80147% of its estimated natural flow past this gage. And because the reconstruction was fit to gage-era data, the overlap shows how well trees track the river (the authors report the models explain 63–76% of gage variance) — it is a calibration, not an independent test.
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 |
|---|---|---|---|---|---|
| the 2020-22 drought | 2020-12-21 → 2021-05-24 | 22 | 25th (2021-03-01) | 5 weeks | — |
| the 2012-13 drought | 2013-01-14 → 2013-07-29 | 28 | 20th (2013-03-18) | 10 weeks | — |
| unnamed dry spell | 2007-09-17 → 2009-08-17 | 100 | 21st (2009-03-23) | 25 weeks | — |
| unnamed dry spell | 2006-07-10 → 2007-04-16 | 40 | 19th (2006-09-04) | 147 weeks | — |
| the 2002 drought | 2004-03-01 → 2004-09-13 | 28 | 21st (2004-05-03) | 1 week | — |
| the 2002 drought | 2002-04-15 → 2003-07-07 | 64 | 11th (2002-12-23) | 6 weeks | — |
| the 1950s drought | 1956-01-23 → 1957-06-10 | 72 | 15th (1956-04-02) | 2 weeks | — |
| the 1950s drought | 1955-01-03 → 1955-09-26 | 38 | 14th (1955-02-14) | 91 weeks | — |
| the 1950s drought | 1954-03-22 → 1954-09-13 | 25 | 22nd (1954-06-07) | 145 weeks | — |
| the 1950s drought | 1950-01-02 → 1951-10-01 | 91 | 16th (1951-05-07) | 9 weeks | — |
| unnamed dry spell | 1948-10-11 → 1949-08-15 | 44 | 15th (1949-02-14) | 120 weeks | — |
| unnamed dry spell | 1944-10-30 → 1947-02-10 | 119 | 14th (1946-06-24) | 23 weeks | — |
| unnamed dry spell | 1943-11-29 → 1944-06-26 | 30 | 15th (1944-03-13) | 160 weeks | — |
| the 1930s Dust Bowl drought | 1939-08-07 → 1942-06-22 | 150 | 3rd (1940-01-08) | 3 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 $38,748,835 in drought-caused claims across Boulder, Larimer, Weld counties — 15.2% of all insured crop losses there. The worst year was 2022 ($8,829,713).
USDA crop-insurance indemnities where the recorded cause of loss is drought, summed over the counties this district's gages sit in. Counties overlap water districts imperfectly, and insured-crop claims are a floor on drought damage, not a total. Source: USDA RMA cause-of-loss files.
When this basin claimed its water
Every bar is a year’s new appropriations (1,087 rights across 102 years of shared record), colored by that year’s wetness from the barcode above. Here the correlation is +0.17 — 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 ↗
21 systems touch this district (21 community systems reporting 420,513 people served, a figure that counts a wholesaler's customers twice); 1 of them carries an open health-based violation on EPA's record.
| System | Serves | Source | Here |
|---|---|---|---|
| GREELEY CITY OF | 132,310 | Surface water | 10% of its area |
| LOVELAND CITY OF | 91,077 | Surface water | 100% of its area |
| FT COLLINS LOVELAND WD | 63,532 | Purchased surface water | 24% of its area |
| JOHNSTOWN TOWN OF | 27,295 | Surface water | 97% of its area |
| LITTLE THOMPSON WD | 25,654 | Purchased surface water | 74% of its area |
| WINDSOR TOWN OF | 23,500 | Purchased surface water | 3% of its area |
| ESTES PARK TOWN OF | 16,722 | Surface water | 100% of its area |
| BERTHOUD TOWN OF | 14,211 | Surface water | 100% of its area |
and 13 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 ↗
14 reaches over 74.7 miles, held by the Colorado Water Conservation Board so that water stays in the stream. Every reach, with its schedule and case →
- Redstone Creek, 16.33 mi: 6.2 (05/01 - 06/15) cfs (appropriated 2021, 21CW3208) · dossier
- Big Thompson River, 11.9 mi: 15 (11/1 - 4/30), 40 (5/1 - 10/31) cfs (appropriated 1989, 89CW0200) · dossier
- North Fork Big Thompson River, 7.3 mi: 2 (11/1 - 3/31), 6 (4/1 - 10/31) cfs (appropriated 1989, 89CW0201) · dossier
- Sheep Creek, 6.7 mi: 0.5 (11/1 - 3/31), 1 (4/1 - 10/31) cfs (appropriated 1989, 89CW0210) · dossier
- North Fork Big Thompson River, 5.3 mi: 3.5 (11/1 - 3/31), 8 (4/1 - 10/31) cfs (appropriated 1989, 89CW0204) · dossier
- Miller Fork, 4.2 mi: 0.85 (1/1 - 4/30), 3 (5/1 - 9/30), 1 (10/1 - 12/31) cfs (appropriated 1989, 89CW0203) · dossier
and 8 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 1861-06-01 to 2021-01-29. Of the 20 structures with a yield estimate, the median one’s senior right was in priority 100% of a median irrigation season and 61% in a dry one. 25 abandonment screens and 23 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: 1819 across 1296 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.
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 | 186 | 1875-06-30 |
| 2017 | 355 | 269 | 1881-02-01 |
| 2018 | 365 | 269 | 1876-05-10 |
| 2019 | 365 | 266 | 1881-02-01 |
| 2020 | 366 | 195 | 1869-04-01 |
| 2021 | 349 | 198 | 1867-04-15 |
| 2022 | 365 | 241 | 1867-04-15 |
| 2023 | 331 | 229 | 1869-04-01 |
| 2024 | 366 | 193 | 1881-02-01 |
| 2025 | 365 | 312 | 1881-02-01 |
Why diversions stopped — call-based explanations
Sustained diversion stops matched to senior administrative calls.
- BARNES DITCH (0400501) DWR↗ stopped 2025-09-28 (5+ days) — call at B H EATON DITCH curtailing 100% of its decreed rate [heuristic-partial]
- MARIANO DITCH (0400534) DWR↗ stopped 2025-09-09 (8+ days) — call at HILLSBOROUGH DITCH curtailing 100% of its decreed rate [heuristic-strong]
- BEELINE DITCH (0400587) DWR↗ stopped 2025-09-08 (20+ days) — call at LOWER LATHAM DITCH curtailing 100% of its decreed rate [heuristic-strong, district-confirmed]
- HANDY DITCH (0400521) DWR↗ stopped 2025-09-03 (17+ days) — call at HILLSBOROUGH DITCH curtailing 100% of its decreed rate [heuristic-partial]
- BARNES DITCH (0400501) DWR↗ stopped 2025-07-28 (48+ days) — call at LOWER LATHAM DITCH curtailing 99% of its decreed rate [heuristic-partial, district-confirmed]
- BEELINE DITCH (0400587) DWR↗ stopped 2025-07-28 (8+ days) — call at LOWER LATHAM DITCH curtailing 100% of its decreed rate [heuristic-strong, district-confirmed]
- MARIANO DITCH (0400534) DWR↗ stopped 2025-07-02 (29+ days) — call at OSBORNE CAYWOOD DITCH curtailing 100% of its decreed rate [heuristic-strong]
- GEORGE RIST DITCH (0400520) DWR↗ stopped 2025-07-01 (9+ days) — call at OSBORNE CAYWOOD DITCH curtailing 100% of its decreed rate [heuristic-strong]
- GEORGE RIST DITCH (0400520) DWR↗ stopped 2025-06-02 (15+ days) — call at PREWITT INLET CANAL curtailing 55% of its decreed rate [heuristic-partial, district-confirmed]
- EVANSTOWN DITCH (0400517) DWR↗ stopped 2025-05-30 (7+ days) — call at OSBORNE CAYWOOD DITCH curtailing 100% of its decreed rate [heuristic-strong]
- DILLE TUNNEL (0400540) DWR↗ stopped 2025-05-08 (13+ days) — call at LOWER PLATTE BEAVER D curtailing 100% of its decreed rate [heuristic-partial, district-confirmed]
- BEELINE DITCH (0400587) DWR↗ stopped 2025-04-30 (59+ days) — call at BIJOU CANAL curtailing 100% of its decreed rate [heuristic-strong, district-confirmed]
Right yield — how often could these rights actually divert?
Share of irrigation-season days each structure's rights were not called out, derived from the 22-year district-scoped call record (senior right = floor, junior right = ceiling constraint). Call-record-derived; DWR's own analysis governs where available.
| Structure | Senior priority | Senior right: median / dry yr | Junior right: median / dry yr |
|---|---|---|---|
| HANDY DITCH (0400521) DWR↗ | 1861-11-10 | 100.0% / 61.2% | 6.1% / 0.0% |
| BARNES DITCH (0400501) DWR↗ | 1861-11-10 | 100.0% / 61.2% | 5.6% / 0.0% |
| HOME SUPPLY DITCH (0400524) DWR↗ | 1861-11-10 | 100.0% / 61.2% | 5.6% / 0.0% |
| BOULDER LARIMER CO IRR MFG D (0400588) DWR↗ | 1875-06-30 | 58.0% / 16.8% | 5.6% / 0.0% |
| LOVELAND GREELEY CANAL (0400532) DWR↗ | 1861-11-10 | 100.0% / 61.2% | 5.6% / 0.0% |
| LOUDEN DITCH (0400530) DWR↗ | 1861-11-10 | 100.0% / 61.2% | 5.6% / 0.0% |
| DILLE TUNNEL (0400540) DWR↗ | 1861-11-10 | 100.0% / 61.2% | 5.6% / 0.0% |
| GEORGE RIST DITCH (0400520) DWR↗ | 1861-11-10 | 100.0% / 61.2% | 5.6% / 0.0% |
| OLYMPUS TUNNEL (0401000) DWR↗ | 1861-11-10 | 100.0% / 61.2% | 5.6% / 0.0% |
| ESTES PARK FOOTHILLS PL (0400516) DWR↗ | 1933-09-14 | 8.2% / 0.0% | 8.2% / 0.0% |
| HILLSBOROUGH DITCH (0400523) DWR↗ | 1861-11-10 | 100.0% / 61.2% | 5.6% / 0.0% |
| HOME SUPPLY DITCH DRY CREEK DIVERSION (0400531) DWR↗ | 1881-07-15 | 5.6% / 0.0% | 5.6% / 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 ~1994 — idleness that begins before then may be unreported use, not nonuse (flagged † below).
- COLE WELL 1 (0400672) DWR↗ (1956-04-30, 0.2 cfs decreed): last active 1962 — 63 years idle † predates modern reporting era — last recorded activity predates this basin's modern reporting era (~1994) -- early absence of record is weak evidence of nonuse
- LAWN RES (0404167) DWR↗ (1902-06-10, 0.0 cfs decreed): last active 1980 — 45 years idle † predates modern reporting era — last recorded activity predates this basin's modern reporting era (~1994) -- early absence of record is weak evidence of nonuse
- HERHOLD DITCH (0400706) DWR↗ (1975-03-20, 0.2 cfs decreed): last active 1981 — 44 years idle † predates modern reporting era — last recorded activity predates this basin's modern reporting era (~1994) -- early absence of record is weak evidence of nonuse
- JORDAN WELL 1 (0405006) DWR↗ (1955-07-02, 1.5 cfs decreed): last active 1981 — 44 years idle † predates modern reporting era — last recorded activity predates this basin's modern reporting era (~1994) -- early absence of record is weak evidence of nonuse
- BARTHOLF DITCH 1 (0400568) DWR↗ (1899-06-22, 0.8 cfs decreed): last active 1990 — 35 years idle † predates modern reporting era — last recorded activity predates this basin's modern reporting era (~1994) -- early absence of record is weak evidence of nonuse
- BARTHOLF DITCH 2 (0400569) DWR↗ (1899-06-22, 1.3 cfs decreed): last active 1990 — 35 years idle † predates modern reporting era — last recorded activity predates this basin's modern reporting era (~1994) -- early absence of record is weak evidence of nonuse
- HERSHMAN DITCH 2 (0400571) DWR↗ (1897-05-31, 1.0 cfs decreed): last active 1990 — 35 years idle † predates modern reporting era — last recorded activity predates this basin's modern reporting era (~1994) -- early absence of record is weak evidence of nonuse
- KINKAID DITCH (0400572) DWR↗ (1892-12-31, 0.8 cfs decreed): last active 1990 — 35 years idle † predates modern reporting era — last recorded activity predates this basin's modern reporting era (~1994) -- early absence of record is weak evidence of nonuse
- MORAINE PARK WELL 1-4019 (0405568) DWR↗ (1959-07-01, 0.2 cfs decreed): last active 1999 — 26 years idle
- JAYHAWKER PIT M-1977-427 (0405575) DWR↗ (1981-01-01, 0.0 cfs decreed): last active 1999 — 26 years idle
Compliance screens (23 advisory flags)
Screened 68 of 1296 structures with rights (115 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.
- ADAMS TUNNEL (0404634) DWR↗: Observed p99 daily rate 560.0 cfs (max 842.3) exceeds total decreed absolute 116.6 cfs across 36608 recorded day(s).
- HERHOLD DITCH (0400706) DWR↗: Observed p99 daily rate 212.0 cfs (max 212.0) exceeds total decreed absolute 0.2 cfs across 344 recorded day(s).
- EVANSTOWN DITCH (0400517) DWR↗: Observed p99 daily rate 37.0 cfs (max 82.5) exceeds total decreed absolute 29.3 cfs across 25791 recorded day(s).
- UNION DITCH (0400582) DWR↗: Observed p99 daily rate 16.4 cfs (max 33.0) exceeds total decreed absolute 12.0 cfs across 7047 recorded day(s).
- RIST GOSS DITCH (0400541) DWR↗: Observed p99 daily rate 11.0 cfs (max 18.6) exceeds total decreed absolute 6.4 cfs across 9462 recorded day(s).
- WELDON SPG (0401629) DWR↗: Observed p99 daily rate 10.0 cfs (max 18.0) exceeds total decreed absolute 0.1 cfs across 1142 recorded day(s).
- R W WAGNER RESERVOIR (0403719) DWR↗: Observed p99 daily rate 10.0 cfs (max 12.6) exceeds total decreed absolute 7.6 cfs across 362 recorded day(s).
- BLACK CANNON DITCH (0400561) DWR↗: Observed p99 daily rate 6.1 cfs (max 6.1) exceeds total decreed absolute 5.0 cfs across 790 recorded day(s).
- A G PEARSON PL (0400551) DWR↗: Observed p99 daily rate 5.0 cfs (max 23.0) exceeds total decreed absolute 2.4 cfs across 9074 recorded day(s).
- JIM EGLIN DITCH (0400596) DWR↗: Observed p99 daily rate 5.0 cfs (max 9.0) exceeds total decreed absolute 3.6 cfs across 12177 recorded day(s).
Seniority (top structures by decreed rate)
| Structure | Senior priority date | Rights | Decreed abs (cfs) | Decreed abs (AF) | Conditional? |
|---|---|---|---|---|---|
| HANDY DITCH (0400521) DWR↗ | 1861-11-10 | 24 | 2250.8 | 0 | — |
| BARNES DITCH (0400501) DWR↗ | 1861-11-10 | 27 | 2021.2 | 0 | — |
| HOME SUPPLY DITCH (0400524) DWR↗ | 1861-11-10 | 29 | 1305.4 | 0 | — |
| BOULDER LARIMER CO IRR MFG D (0400588) DWR↗ | 1875-06-30 | 8 | 1136.7 | 0 | — |
| LOVELAND GREELEY CANAL (0400532) DWR↗ | 1861-11-10 | 30 | 867.0 | 0 | yes |
| LOUDEN DITCH (0400530) DWR↗ | 1861-11-10 | 31 | 864.6 | 0 | — |
| DILLE TUNNEL (0400540) DWR↗ | 1861-11-10 | 27 | 791.0 | 0 | — |
| GEORGE RIST DITCH (0400520) DWR↗ | 1861-11-10 | 24 | 586.8 | 0 | — |
| OLYMPUS TUNNEL (0401000) DWR↗ | 1861-11-10 | 21 | 566.0 | 0 | — |
| ESTES PARK FOOTHILLS PL (0400516) DWR↗ | 1933-09-14 | 1 | 550.0 | 0 | — |
| HILLSBOROUGH DITCH (0400523) DWR↗ | 1861-11-10 | 7 | 284.1 | 0 | yes |
| HOME SUPPLY DITCH DRY CREEK DIVERSION (0400531) DWR↗ | 1881-07-15 | 1 | 275.0 | 0 | — |
| SOUTH SIDE DITCH (0400543) DWR↗ | 1861-11-10 | 26 | 246.1 | 0 | — |
| LOVELAND PIPELINE (0400511) DWR↗ | 1861-11-10 | 24 | 159.9 | 223 | yes |
| ADAMS TUNNEL (0404634) DWR↗ | 1965-06-24 | 2 | 116.6 | 0 | — |
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 (18 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 24 filings, with excerpts
| Case | What it asks | County | Excerpt |
|---|---|---|---|
2026CW3039
|
— | — | CASE NO. 20 26CW3039; STATE ENGINEER AND WATER DIV 2 ENGINEER vs. ANDREW STOREY – Verified Complaint for Injunctive Relief, Penalties, and Costs. This case is being listed in the resume to account for the case number in consecutive order. ---------------------… |
2026CW3040
|
plan for augmentation, new underground right | — | CASE NO. 2026CW3040 , Water Division 2 and CASE NO. 2026CW3135, Water Division 1; JANICE L DUNCAN, 6440 Highline Place, Colorado Springs, CO, 80908 (Please address all pleadings and inquiries regarding this matter to Applicant’s attorney: Philip E. Lopez, Eric… |
2026CW3088
|
plan for augmentation | — | CASE NUMBER 2026CW3088 NORTH RANCH, LLC, c/o Robert L. Myers, 944 Cheyenne Blvd., Colorado Springs, CO 80905; Please direct all correspondence concerning the application to: Ryan W. Farr, Sedona E. Chavez, Monson, Cummins, Shohet & Farr, LLC, 13511 Northgate E… |
2026CW3089
|
— | — | CASE NUMBER 20 26CW3089 ROBERSON LIVING TRUST, c/o Tamara Roberson -George, Rex Roberson, Kevin Roberson, Co-Trustees, 18235 Black Forest Road, Colorado Springs, CO 80908; Please direct all correspondence concerning this application to: David M. Shohet, and Se… |
2026CW3119
|
change of water right, plan for augmentation, new storage right | — | CASE NUMBER 2026CW3119 SHARON AND MARK WEATHERFORD, 12328 S. State Hwy 83, Franktown, CO 80116. (Forward all pleadings and correspondence to Chris D. Cummins and Sedona E. Chavez, Monson, Cummins, Shohet & Farr, LLC, 13511 Northgate Estates Dr., Ste. 250, Colo… |
2026CW3120
4404471 |
reasonable diligence | THE CITY AND | CASE NUMBER 2026CW3120 THE CITY AND COUNTY OF DENVER, ACTING BY AND THROUGH ITS BOARD OF WATER COMMISSIONERS (“Denver Water” or “Applicant”), 1600 West 12th Avenue, Denver, Colorado 80204. Jessica R. Brody, General Counsel, Daniel J. Arnold, James M. Wittler, … |
2026CW3121
|
— | — | CASE NUMBER 2026CW3121 (2018CW3222)… |
2026CW3122
|
plan for augmentation, new underground right | — | CASE NUMBER 2026CW3122 DOUBLE S CONSTRUCTION & DESIGN LLC, ATTN: Scott Berry, 42631 Sager Lane, Parker, CO, 80138. APPLICATION FOR UNDERGROUND WATER RIGHTS FROM NONTRIBUTARY AND NOT-NONTRIBUTARY SOURCES AND APPROVAL OF PLAN FOR AUGMENTATION, IN THE NONTRIBUTAR… |
2026CW3123
|
reasonable diligence | THE CITY AND | CASE NUMBER 2026CW3123 THE CITY AND COUNTY OF DENVER, ACTING BY AND THROUGH ITS BOARD OF WATER COMMISSIONERS (“Denver Water” or “Applicant”), 1600 West 12th Avenue, Denver, Colorado 80204. Jessica R. Brody, General Counsel, Daniel J. Arnold, James M. Wittler, … |
2026CW3124
|
reasonable diligence, make absolute, new underground right | — | CASE NUMBER 2026CW3124 WESTERN EQUIPMENT AND TRUCK, INC. , 2055 1 st Ave., Greeley, CO 80631, 970 -353-6682. P. Andrew Jones, Law Office of P. Andrew Jones, 1213 Founders Circle, Windsor, CO 80550, 970 -297-0570, ajones@pandrewjones.com. APPLICATION TO MAKE CO… |
2026CW3125
0600538 0600565 0600576 |
reasonable diligence | EASONABLE DILIGENCE IN BOULDER | CASE NUMBER 2026CW3125 (90CW108) (99CW125) (12CW72) (20CW3017) APPLICATION FOR FINDING OF REASONABLE DILIGENCE IN BOULDER COUNTY . 1. Name, Mailing Address, Phone Number, and E -mail Address of Applicant . CITY OF LAFAYETTE , c/o Cari Bischoff, Water Resources… |
2026CW3126
0815262 0815263 0815264 |
reasonable diligence, make absolute | — | CASE NUMBER 2026CW3126 MARY GUENZEL CHARITABLE TRUST, P.O. Box 9, Woodland Park, Colorado 80866; Please direct all correspondence concerning this application to: Ryan W. Farr, Monson, Cummins, Shohet & Farr, LLC, 13511 Northgate Estates Drive, Suite 250, Color… |
2026CW3127
|
new underground right | UPPER LARAMIE AQUIFER IN WELD | CASE NUMBER 2026CW3127 THE CITY OF GREELEY, ACTING BY AND THROUGH ITS WATER AND SEWER BOARD, AND THE COLORADO STATE BOARD OF LAND COMMISSIONERS. APPLICATION FOR NONTRIBUTARY UNDERGROUND WATER RIGHTS IN THE UPPER LARAMIE AQUIFER IN WELD COUNTY. I. Name, mailing… |
2026CW3128
|
reasonable diligence, make absolute | — | CASE NUMBER 2026CW3128 Applicant. CHRIS DINSDALE, P.O. Box 1807, Sterling, CO 80751, 970-522-9052 with all correspondence connected herewith being sent to Applicant’s Counsel, David P. Jones, Lawrence Custer Grasmick Jones & Donovan, LLP., 5245 Ronald Regan Bl… |
2026CW3129
|
plan for augmentation, new underground right | PLAN FOR AUGMENTATION IN ELBERT | CASE NUMBER 2026CW3129 VANCE ROBERT ANDRUS & TONI COLLEEN ANDRUS , 6414 Sherman Peak, Castle Rock, Colorado 80108. APPLICATION FOR UNDERGROUND WATER RIGHTS FROM NONTRIBUTARY AND NOT-NONTRIBUTARY SOURCES AND APPROVAL OF PLAN FOR AUGMENTATION IN ELBERT COUNTY . … |
2026CW3130
|
— | — | CASE NUMBER 2026CW 3130 THE CITY OF GREELEY, ACTING BY AND THROUGH ITS WATER AND SEWER BOARD c/o Leah Hubbard, Deputy Director of Water Resources, 1001 – 11th Avenue, 2nd Floor, Greeley, Colorado 80631, leah.hubbard@greeleygov.com, (970) 350-9811. Please send … |
2026CW3131
|
reasonable diligence | — | CASE NUMBER 2026CW3131 CITY OF LOVELAND , Colorado (“Loveland”), c/o Noah Cecil, Assistant City Attorney, 500 East Third Street, #330, Loveland, Colorado 80537, Telephone: (970) 962 - 2434. APPLICATION FOR FINDING OF REASONABLE DILIGENCE IN LARIMER AND WELD CO… |
2026CW3132
|
— | — | CASE NUMBER 2026CW3132 Applicants. THE CENTRAL COLORADO WATER CONSERVANCY DISTRICT AND THE GROUNDWATER MANAGEMENT SUBDISTRICT OF THE CENTRAL COLORADO WATER CONSERVANCY DISTRICT , 3209 West 28 th Street, Greeley, Colorado, 80634, 970-330-4540 with all future co… |
2026CW3133
|
reasonable diligence | — | CASE NUMBER 2026CW3133 CHELEY LAND, LLC AND CHELEY COLORADO CAMPS, LLC (f.k.a. Cheley Colorado Camps, Inc.) , 601 Steele Street, P.O. Box 6525, Denver, CO 80206. c/o Karen L. Henderson, Bushong & Holleman PC, 1966 13th Street, Suite 270, Boulder, CO 80302; (30… |
2026CW3139
|
change of water right | — | CASE NUMBER 2026CW3139 ALBERT WENDELL NELSON REVOCABLE TRUST c/o Wendell Nelson, Trustee 5537 N. County Road 9 Fort Collins, CO 80524 303 -921-4750 Sally Jean Nelson Revocable Trust c/o Wendell Nelson, Trustee 5537 N. County Road 9 Fort Collins, CO 80524 303 -… |
2026CW3140
|
plan for augmentation | PLAN FOR AUGMENTATION IN ELBERT | CASE NUMBER 2026CW3140 DAVID JOE KRAXNER III, 754 Highway 86, Elizabeth, CO, 80107. Philip E. Lopez, Eric K. Trout, Fairfield and Woods, P.C., 1801 California St, Suite 2600, Denver, CO, 80202. APPLICATION FOR A PLAN FOR AUGMENTATION IN ELBERT COUNTY. Subject … |
2026CW3141
|
plan for augmentation | — | CASE NUMBER 2026CW3141 KELTY COLORADO FAMILY LLLP, C/o Bruff Shea, P.O. Box 21, Franktown, Colorado 80166. Please direct all pleadings and correspondence to Applicants counsel: Michael A. Kopp, Trout Raley PC, 1120 Lincoln St., Suite 1600, Denver, CO 80203, (3… |
2026CW3142
|
new underground right | — | CASE NUMBER 2026CW3142 1. Name, address, and telephone number of Applicant and Landowner: 1.1. Applicant and Landowner: CAP LAND LLC, a Colorado limited liability company 47 (“CAP Land”) c/o Lena Vander Laan P.O. Box 105 Henderson, CO 80640 Please direct all c… |
2026CW9
|
reasonable diligence, make absolute | LARIMER | CASE NUMBER 2026CW9 SPRING44 DISTILLING, INC. (“Spring44”), 505 West 66th Street, Loveland, Colorado 80538, Telephone: (970) 445 -7109. APPLICATION FOR FINDINGS OF REASONABLE DILIGENCE AND CLAIM TO MAKE CERTAIN AMOUNTS ABSOLUTE IN LARIMER COUNTY. 2. Lindauer S… |
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 |
|---|---|---|---|---|---|
| BERNHARDT PIT | 37-90-137(11) GRAVEL PIT PLAN | Approved | 2026-12-31 | 0403007 | plan file |
| KAUFFMAN NO.1 PIT | 37-90-137(11) GRAVEL PIT PLAN | Approved | 2026-12-31 | 0402530 | plan file |
| TWO RIVERS P124 PIT | 37-90-137(11) GRAVEL PIT PLAN | Approved | 2026-12-31 | — | plan file |
| WAGNER KAUFFMAN #3 PIT | 37-90-137(11) GRAVEL PIT PLAN | Approved | 2026-12-31 | 0402529 | plan file |
| TOWN OF JOHNSTOWN - HOME SUPPLY | 37-92-308(5) PLANS LESS THAN 5 YEARS | Approved | 2027-03-31 | 0402548 | plan file |
| LARIMER PIT | 37-90-137(11) GRAVEL PIT PLAN | Approved | 2027-07-31 | 0402525 | plan file |
| MILLIKEN TOWN OF | 37-92-308(4) PLAN PENDING COURT APPLICATION | Approved | — | — | plan file |
| BURNCO COLORADO LLC - MILLIKEN RMX BATCH PLANT AND TLT WELL NO. 1 | 37-92-308(4) PLAN PENDING COURT APPLICATION | Pending | — | 0402561 | plan file |
| TROUT HAVEN RESORTS | 37-92-308(5) PLANS LESS THAN 5 YEARS | Pending | — | — | plan file |
| AMEN AGGREGATE RESOURCE | 37-90-137(11) GRAVEL PIT PLAN | Division Review | — | 0402560 | plan file |
| BONSER PIT | 37-90-137(11) GRAVEL PIT PLAN | Division Review | — | 0402560 | plan file |
| BROWNWOOD PIT | 37-90-137(11) GRAVEL PIT PLAN | Division Review | — | 0402546 | plan file |
| CHALLENGER PIT | 37-90-137(11) GRAVEL PIT PLAN | Division Review | — | 0402560 | plan file |
| GARDELS PIT | 37-90-137(11) GRAVEL PIT PLAN | Division Review | — | 0402560 | plan file |
| KIRTRIGHT PIT | 37-90-137(11) GRAVEL PIT PLAN | Division Review | — | 0402560 | 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 2026-10-13 · 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 |
|---|---|---|---|---|---|
| BIG THOMPSON BL MORAINE PARK NR ESTES PARK, CO | 10.9 | 2026-10-13 09:05 |
Where water has been sampled
Source Register of another agency · fetched 2026-10-08 · verify at Water Quality Portal ↗
The portal lists 973 sampling stations in this district's watershed (Big Thompson 10190006), of which 85 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 (35), USGS Colorado Water Science Center (33), Colorado State University Agricultural Water Quality Program (Volunteer) (12). Most-sampled groups: Physical, Nutrient, Inorganics, Major, Metals, 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 ↗
21 community systems touch this district. 1 carries an open health-based violation on EPA's record. EPA sampled 11 of them for PFAS in 2023–25; 1 had PFOA or PFOS at or above the 2024 limit.
| System | Serves | EPA record | PFAS (UCMR 5) | Lead, latest 90th pct |
|---|---|---|---|---|
| PINEWOOD SPRINGS WD | 745 | 3 open health-based | not sampled | 0.001 mg/L |
| LITTLE THOMPSON WD | 25,654 | clean, last 12 quarters | PFOA at or over the limit | — |
| GREELEY CITY OF | 132,310 | 3 of 12 quarters with a violation | none detected | 0.004 mg/L |
| LOVELAND CITY OF | 91,077 | clean, last 12 quarters | none detected | 0.0033 mg/L |
| FT COLLINS LOVELAND WD | 63,532 | clean, last 12 quarters | none detected | 0.002 mg/L |
| JOHNSTOWN TOWN OF | 27,295 | 1 of 12 quarters with a violation | none detected | 0.001 mg/L |
| WINDSOR TOWN OF | 23,500 | 1 of 12 quarters with a violation | none detected | 0.0058 mg/L |
| ESTES PARK TOWN OF | 16,722 | 1 of 12 quarters with a violation | none detected | 0.0014 mg/L |
| BERTHOUD TOWN OF | 14,211 | clean, last 12 quarters | none detected | 0.01 mg/L |
| MILLIKEN TOWN OF | 9,200 | 2 of 12 quarters with a violation | none detected | 0.0 mg/L |
and 11 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.
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
DWR administration numbers encode appropriation and adjudication dates; lower is more senior.
This week's diagnostic
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System status
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Active river calls
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Hydrographs vs. historical envelope
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Anomaly flags
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Snowpack — no snow on the ground at 2 SNOTEL sites — normal for the date; the snow year begins in October and typically peaks around April 27. Runoff outlook — Big Thompson R at Canyon Mouth: even odds of at least 48 kAF over 06-01 to 09-30 — 61% 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) | Median (in) | % of median | Typical peak |
|---|---|---|---|---|---|
| Bear Lake | 9490 | 0.1 | 0.0 | — | April 27 (19.8 in) |
| Willow Park | 10710 | 0.1 | 0.0 | — | April 29 (21.0 in) |
Big Thompson R at Canyon Mouth — 06-01 to 09-30 volume, thousand acre-feet (chance the volume is AT LEAST this):
| 90% | 70% | 50% | 30% | 10% | Normal |
|---|---|---|---|---|---|
| 38 | 43 | 48 | 53 | 62 | 79 |
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: 9 parent disagreements, 9 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 23 streams, 14 agree. Know this water? Tell us →
| Stream | This site routes it to | DWR routes it to |
|---|---|---|
| Twin Sisters Creek | the mainstem | West Fork Little Thompson River |
| North Fork Fish Creek | the mainstem | Fish Creek |
| Fish Creek | the mainstem | Buckhorn Creek |
| Stove Prairie Creek | the mainstem | Buckhorn Creek |
| Dry Creek | the mainstem | Cedar Creek |
| Wind River | the mainstem | Aspen Brook |
| Dry Creek | the mainstem | Little Thompson River |
| Dry Creek | the mainstem | Little Thompson River |
Sizable streams DWR maps here that this network does not carry:
Cedar Creek (11 mi) · Glacier Creek (10 mi) · Ryan Gulch (6 mi) · Dry Gulch (5 mi) · Thornton Gulch (5 mi) · Hayden Creek (4 mi) · Aspen Brook (4 mi) · Spruce Creek (4 mi)