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RAINBOW LAKE (M COTTONWD CRK)

Structure dossier · WDID 1103535 · RESERVOIR · MIDDLE COTTONWOOD CREEK · DWR record

Rainbow Lake (M Cottonwd Crk) is a reservoir on Middle Cottonwood 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 2026-10-18 07:34 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

Where this structure is measured

GageFlowing nowRecordHow we know
MIDDLE COTTONWOOD CREEK BELOW RAINBOW LAKE MCWCRLCO 3.19 cfs 2018–2018, 2 days co-located, 132 m

A green link is DWR's own: either its telemetry inventory maps this WDID to that station, or the station is named for this WDID (0700553 → 0700553A). An amber one is ours — the station sits within 250 m and shares a distinctive word with this structure's name, which is a strong hint rather than a DWR statement that this gage meters this structure. Wrong? Tell us.

In short

RAINBOW LAKE (M COTTONWD CRK) holds 4 decreed rights on MIDDLE COTTONWOOD CREEK. No active call senior to its rights reaches its district today (21 active calls checked), so it is in priority now. 17 further calls state no district and sit outside this one, so they are counted here rather than assumed either way. That is today's position; the weeks ahead cannot be projected for it: no call in the record verifiably applies to this district (statements and caller locations checked). In a median year over its last 15 recorded years it diverts 35 acre-feet. It was a party to 3 court cases that also touched 6 other structures.

Assembled from the figures on this page — every number above is checked against them before it is shown (7 checked). The detail, with its method, is in the cards below.

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

● In priority — no active call senior to this structure's rights affects its district (21 active call(s) checked).

17 further calls state no district and sit outside this one, so they are counted here rather than assumed either way.

Which of its rights are out of priority?

The outlook for the weeks ahead is not computable for this structure: no call in the record verifiably applies to this district (statements and caller locations checked). 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 1864-12-19 — 23rd most senior of the 1491 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: THOMPSON DITCH (1864-12-19). Immediately behind: COTTONWOOD LAKE (1864-12-19).

On MIDDLE COTTONWOOD CREEK at river mile 51.7, it is 58th of 63 down the reach. Immediately upstream: 1114606. Immediately downstream: 1114607.

Position on the modelled network, not a claim about whose water this is — a stream carries water from many rights at once, and diverted water returns to it.

Decreed rights (4)

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
5467.00000 1864-12-191890-06-19 0.0 cfs 0.0 0.595 cfs Augmentation 3
41932.00000 1964-10-211969-07-09 106.21 AF 0.0 — Fishery A179
53368.00000 1996-02-121996-12-31 0.0 cfs 0.0 10.0 cfs Irrigation, Municipal +2 96CW0017, 05CW0051
58073.00000 2008-12-302008-12-31 0.0 cfs 0.0 2.0 cfs Augmentation 08CW0106

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.

Recorded use (last 15 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 35 AF. Its most recent year on record, 2022, came in at 20 AF — 57% of that, and 3rd lowest of the 15 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)
2003 27 4th lowest of 15 · 77% of median 160 46 1.8
2009 103 15th lowest of 15 · 294% of median — 30 6.4
2010 35 6th lowest of 15 · 100% of median 1 89 1.7
2011 54 12th lowest of 15 · 154% of median 19 14 7.1
2012 40 10th lowest of 15 · 114% of median 8 16 4.3
2013 19 2nd lowest of 15 · 54% of median 5 12 2.6
2014 35 6th lowest of 15 · 100% of median 5 157 4.3
2015 28 5th lowest of 15 · 80% of median — 184 0.1
2016 14 1st lowest of 15 · 40% of median — 61 2.0
2017 98 14th lowest of 15 · 280% of median — 177 5.5
2018 48 11th lowest of 15 · 137% of median — 142 0.3
2019 37 9th lowest of 15 · 106% of median — 89 0.2
2020 35 6th lowest of 15 · 100% of median 3 30 3.2
2021 75 13th lowest of 15 · 214% of median — 214 3.2
2022 20 3rd lowest of 15 · 57% of median — 304 0.1

How good is our record of it?

Grade B (7/10 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 4 right(s), seniority decoded
diversion record stale 1596 measured days, but newest is 1427 day(s) before the data's end (target 450)
record continuity sparse 37% of the irrigation seasons in 2002-2022 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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