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MAIN RESERVOIR

Structure dossier · WDID 0803405 · RESERVOIR · CLEAR CREEK · DWR record

Main Reservoir is a reservoir on Clear Creek in Colorado. This page is its public record: the water it has a right to, whether it may take it today, and its history, compiled from the Colorado Division of Water Resources.

Source DWR administrative record · verify at DWR structure ↗ Source DWR administrative record · verify at DWR diversion records ↗ Source Our computation, scored against a reference · scored against DWR's call analysis, see /methods

Where this page's figures come from

Generated 2026-10-14 23:54 by Hydrohistorian. Sources: DWR HydroBase snapshot HydroBase_CO_20260928 (history) + CDSS REST (current), USGS NWIS cross-checks. Engine v0.5.0 (dd58e60) — every figure regenerates from this named code version and data image.

The record and the river

Download this structure

Everything on this page as data you can work with — and a README that makes it citable: the HydroBase snapshot it was built from, the build commit, what every column means, the method behind each derived figure, and that method's stated limits.

⇩ Full record (.zip) Print / save as PDF

Or one table at a time: rights.csv · annual_use.csv · curtailment_now.csv · court_cases.csv · co_parties.csv · call_climatology.csv

What is in the bundle
  • rights.csv — every decreed right, most senior first, with admin numbers, dates, amounts, uses and case numbers.
  • annual_use.csv — recorded diversion by year, with releases accounted separately.
  • curtailment_now.csv — each right's current priority status and how often it was out across analog years.
  • court_cases.csv — the cases attached to its rights.
  • co_parties.csv — the other structures that were parties to those cases. Not available anywhere else.
  • call_climatology.csv — how often each right has been out of priority by week of season, with confidence intervals and the seasons the record could actually judge.
  • README.txt — provenance, methods, limits, disclaimer, and links back to DWR's own records for verification.

Where it sits

Location as DWR records it (storage). Faint dots are the neighbouring water; click any to open it.

Current administration

● Junior rights called out — call at SOUTH PLATTE RIVER AT WATERTON (SOUTH PLATTE RIVER, priority 1863-12-30).

● Junior rights called out — call at CHATFIELD RESERVOIR (SOUTH PLATTE RIVER, priority 1865-12-30).

Which of its rights are out of priority?

The outlook for the weeks ahead is not computable for this structure: this structure is not on the modelled flow network, so no reference gage can honestly stand in for it. Today’s position is a separate question, and it is answered in Current administration above — that screen reads the district’s active calls and needs no reference gage.

Where it sits in line

Priority 1860-05-15 — 4th most senior of the 21886 structures with decreed rights in this water districtDWR's administrative subdivision of a river basin; the unit calls are usually stated in..

Under prior appropriationColorado's rule for sharing water: first in time, first in right. Age decides, not proximity or need., everything ahead of it in this line is satisfied in full before it receives any water. Immediately ahead: WALTER S WELTON RES (1860-05-15). Immediately behind: EAST RESERVOIR (1860-05-15).

Decreed rights (16)

Admin noDWR's numeric encoding of a water right's seniority. Smaller is more senior; the integer part counts days from 1849-12-31 to the date that ranks the right. AppropriatedWhen water was first put to beneficial use. It sets seniority unless a prior adjudication date is later. AdjudicatedWhen the water court confirmed the right. A use decreed in 1975 was not a decreed use in 1955, however old the appropriation is. AbsoluteA right actually put to use, as opposed to conditional -- a placeholder for a use not yet made. ConditionalA right reserving a place in line for a use not yet made; it must be diligently pursued or it lapses. Alt-pointAn absolute amount decreed at another structure that may be diverted here instead -- an alternate point of diversion or an exchange. DWR calls this the APEX amount; a right showing 0.0 absolute but an alt-point amount is exercised here under another structure's decree. Decreed forWhat the court said this water may be used for -- irrigation, municipal supply, augmentation and so on.Case
3788.00000 1860-05-151884-10-04 0.0 cfs 0.0 0.093 cfs Irrigation, Municipal +7 09CW0107, 13CW0017
3792.00000 1860-05-191884-10-04 0.0 cfs 0.0 0.046 cfs Irrigation, Municipal +7 13CW0017, 09CW0107
3804.00000 1860-05-311884-10-04 0.0 cfs 0.0 0.218 cfs Irrigation, Municipal +7 09CW0107, 13CW0017
3818.00000 1860-06-141884-10-04 0.0 cfs 0.0 0.064 cfs Irrigation, Municipal +7 13CW0017, 09CW0107
4151.00000 1861-05-131884-10-04 0.0 cfs 0.0 0.046 cfs Irrigation, Municipal +7 09CW0107, 13CW0017
4152.00000 1861-05-141884-10-04 0.0 cfs 0.0 0.006 cfs Irrigation, Municipal +7 13CW0017, 09CW0107
4171.00000 1861-06-021884-10-04 0.0 cfs 0.0 0.064 cfs Irrigation, Municipal +7 09CW0107, 13CW0017
4180.00000 1861-06-111884-10-04 0.0 cfs 0.0 0.022 cfs Irrigation, Municipal +7 13CW0017, 09CW0107
4535.00000 1862-06-011884-10-04 0.0 cfs 0.0 0.009 cfs Irrigation, Municipal +7 09CW0107, 13CW0017
5615.00000 1865-05-161884-10-04 0.0 cfs 0.0 0.009 cfs Irrigation, Municipal +7 13CW0017, 09CW0107
7712.00000 1871-02-111884-10-04 0.0 cfs 0.0 0.921 cfs Irrigation, Municipal +7 09CW0107, 13CW0017
9121.00000 1874-12-211884-10-04 0.0 cfs 0.0 5.775 cfs Irrigation, Municipal +7 13CW0017, 09CW0107
12136.00000 1883-03-241884-10-04 0.0 cfs 0.0 2.756 cfs Irrigation, Municipal +7 09CW0107, 13CW0017
16718.13966 1888-03-271936-05-13 0.0 cfs 0.0 3.128 cfs Irrigation, Municipal +7 13CW0017, 09CW0107
18415.00000 1900-06-021936-05-13 0.0 cfs 0.0 1.37 cfs Irrigation, Municipal +7 09CW0107, 13CW0017
18659.00000 1901-02-011936-05-13 606.51 AF 0.0 — Storage, Irrigation +8 18CW3230, 94CW0197 +4

Amounts marked cfs are flow rates; AF are stored volumes (storage rights are decreed in acre-feet). An absolute amount of 0.0 beside an alt-point amount is not a dead right: the water is decreed at another structure, and that row records permission to divert it here instead (an alternate point or exchange). A case listing several numbers reflects the original decree plus later change cases.

How often is it out of priority?

Across the 11 seasons whose call record is complete enough to judge this structure (2016, 2017, 2018, 2019, 2020, 2021, 2022, 2023, 2024, 2025, 2026), week by week from April.

most senior right · admin 3788.00000 · never out of priority in these seasons
AprMayJunJulAugSep
middle right · admin 4535.00000 · never out of priority in these seasons
AprMayJunJulAugSep
most junior right · admin 18659.00000 · peaks at 10 of 11 seasons
AprMayJunJulAugSep
Why only 11 seasons, and what the bars mean

Each bar is one week: how many of those seasons that right was out of priority under a call this site can lawfully attribute to this structure. Green is never, red is every season on record.

The short record is a property of DWR's data, not of the river. A call only counts against a structure when we can establish it applies — by the districts named in its set comments, or by stream mile on the same source. DWR did not begin stating affected districts routinely until about 2015: fewer than one call in ten can be judged before then, against roughly two in three since. A season we cannot judge is not a season without calls, so it is dropped rather than counted as quiet — 12 seasons dropped here.

This is a frequency over past seasons, not a forecast. It says nothing about what the division engineer will do this year.

Recorded use (last 7 years on record)

Years far under the decreed amount? That gap has a name — paper water vs. wet water, explained on this structure.

In a median year this structure has a recorded diversion of 158 AF. Its most recent year on record, 2023, came in at 124 AF — 78% of that, and 1st lowest of the 5 years with a recorded volume.

This structure records both diversions and reservoir releases — they are separate water movements and are accounted separately below.

YearDiverted (AFA volume: one acre covered a foot deep, about 326,000 gallons -- roughly a suburban household's outdoor use for a year.)Compared with its own recordReleased (AF)Days recordedPeak (cfs)
2019 189 4th lowest of 5 · 120% of median — 33 4.5
2020 158 3rd lowest of 5 · 100% of median — 32 4.0
2021 124 1st lowest of 5 · 78% of median 326 102 3.2
2022 213 5th lowest of 5 · 135% of median 402 365 5.6
2023 124 1st lowest of 5 · 78% of median 697 304 5.3
2024 — no recorded volume 125 0 —
2025 — no recorded volume 0 0 —

How good is our record of it?

Grade B (8/10 points) — the components below are the finding; the letter alone is not.

The rubric, component by component
CheckStateDetail
identity complete name, type, and water source all on file
decreed rights on file 16 right(s), seniority decoded
diversion record present 836 measured days; currency unknown (no data-coverage date to compare against)
record continuity patchy 61% of the irrigation seasons in 2019-2025 carry measured days
published-record stability stable no upstream revisions recorded against this structure

Advisory reading aid on public data — not an administrative or legal conclusion, not a title opinion, and not a substitute for DWR administration or an engineer's analysis. Methodology review status is disclosed at hydrohistorian's basin pages.

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