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FILLY LAKE

Structure dossier · WDID 0603372 · RESERVOIR · BOULDER CREEK · DWR record

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 2026-10-13 15:35 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
FILLY LAKE OUTLET FILOUTCO 0.08 cfs 2026–2026, 151 days DWR telemetry mapping
FILLY LAKE INLET FILINLCO — 2025–2026, 12 days DWR telemetry mapping

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.

Flowing now

0.08 cfs as of 2026-10-13 14:30 (1.1 h ago)

Provisional 15-minute telemetry from FILOUTCO ↗ (FILLY LAKE OUTLET). Raw, not the approved record — it is never merged into the diversion history below. DWR publishes the official diversion record after the water year closes and is approved, which is why that record ends months back while this reads minutes ago.

In short

FILLY LAKE holds 2 decreed rights on BOULDER CREEK. A call at RURAL DITCH on BOULDER CREEK (1862-05-09), and 1 other currently reaches it: fully called out. 7 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: only 1 analog year(s) have both flow and a complete administration record; 4 needed. In a median year over its last 8 recorded years it diverts 786 acre-feet. It was a party to 1 court cases that also touched 2 other structures.

Assembled from the figures on this page — every number above is checked against them before it is shown (10 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

● Fully called out — call at RURAL DITCH (BOULDER CREEK, priority 1862-05-09).

● Fully called out — call at HOWELL DITCH (BOULDER CREEK, priority 1859-12-01).

Which of its rights are out of priority?

The outlook for the weeks ahead is not computable for this structure: only 1 analog year(s) have both flow and a complete administration record; 4 needed. 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 2002-10-01 — 1816th most senior of the 1867 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: JEWELL MOUNTAIN LAKE (2002-01-23). Immediately behind: 0603376 (2002-10-01).

On MAINSTEM at river mile 26.2, it is 57th of 78 down the reach. Immediately upstream: NWRF RESERVOIR. Immediately downstream: NELSON LAKE NO 1.

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 (2)

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
55791.00000 2002-10-012002-12-31 590.0 AF 0.0 — Irrigation, Industrial +1 23CW3058, 02CW0216
56978.00000 2005-12-312005-12-31 672.42 AF 327.58 AF — Irrigation, Industrial +1 02CW0216, 23CW3058

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 12 seasons whose call record is complete enough to judge this structure (2015, 2016, 2017, 2018, 2019, 2020, 2021, 2022, 2023, 2024, 2025, 2026), week by week from April.

most senior right · admin 55791.00000 · peaks at 12 of 12 seasons
AprMayJunJulAugSep
most junior right · admin 56978.00000 · peaks at 12 of 12 seasons
AprMayJunJulAugSep

Snow sets the clock here. In the driest third of snow years (4 seasons), the call settled in for the season around July 15 (June 3 to July 15 across those years); in 1 of them it never lifted at all. In the middle third (4 seasons), the call settled in for the season around June 24 (June 17 to July 8 across those years); in 1 of them it never lifted at all. In the wettest third (4 seasons), the call settled in for the season around June 24 (June 17 to June 24 across those years); in 2 of them it never lifted at all.

Snow years ranked by the district’s April 1 snow-water percentile across 3 SNOTEL sites; 12 seasons carry both a snow reading and a judgeable call record. How the past played out, not a forecast.

Why only 12 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 — 11 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 9 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 786 AF. Its most recent year on record, 2025, came in at 21 AF — 3% of that, and 1st lowest of the 8 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)
2016 1,637 8th lowest of 8 · 208% of median — 40 33.8
2017 998 6th lowest of 8 · 127% of median — 70 18.7
2018 1,400 7th lowest of 8 · 178% of median 956 107 52.2
2019 955 5th lowest of 8 · 122% of median 659 32 24.8
2021 101 2nd lowest of 8 · 13% of median — 14 3.9
2022 — no recorded volume 387 0 —
2023 617 4th lowest of 8 · 78% of median 47 18 45.0
2024 198 3rd lowest of 8 · 25% of median — 11 32.1
2025 21 1st lowest of 8 · 3% of median — 3 5.6

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 2 right(s), seniority decoded
diversion record stale 295 measured days, but newest is 474 day(s) before the data's end (target 450)
record continuity sparse 15% of the irrigation seasons in 2016-2025 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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