Spring Creek · Limestone · Wisconsin, US

Castle Rock Creek

A fly fishing line stretched over Castle Rock Creek in the Wisconsin driftless area, backlit by evening sun through streamside trees.

A spring creek of the chalk-stream kind — weed-trailing, alkaline, absurdly productive — with a reputation for big browns that didn't get big by being stupid.

Today · Closed season
Pink Shrimp
Forecast · Today
Closed season
Out of season. Try elsewhere.
45% projected
Today's fly
Pink Shrimp
Pink Shrimp
Conditions on the water · Today
Proxy gauge
Level
Rising
Proxy
via Bloody Run Creek
Water temp12.9°C
ClarityUnfishable
Weather6°C
WindN 9 km/h
Pressure1034 hPa
Rain · recent18.8 mm
Rain · ahead0.0 mm

No gauge on this water — conditions are inferred from Bloody Run Creek. The trend transfers, the absolute level does not.

Water temperature for Brown Trout
Ideal
13°C est.ideal 10–16°C
0°14°28°
How to fish it · for Brown Trout
When
Nymphing can work through most of the day.
Where
Cover mixed depths.
Method
Start with tight-line nymphs and adjust if fish rise or drift higher.
Kit
9 ft #4 rod, floating line, 12 ft tapered leader to 4–5 lb fluoro tippet.
Likely species
Mayflies
Chironomids
Gammarids
Hatch timeline · todayPeak at 12pm

12pm(now) — Eastern Blue-Winged Olive

Stage: On emergersApproach: Emerger or dryActivity: 38%
Peak emergence window

Peak activity at 12pm — Eastern Blue-Winged Olive (Eastern Blue-Winged Olive, Peak emergence window)

Sub-surface · on the nymphunder the surface

Hatch predictions

Supporters see the full sub-surface read.

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Beyond the hatch · worth watchingambient prey(1)

Hatch predictions

Top prey shown — see all 2 as a supporter.

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Evidence
Records-basedModerate confidence

Based on species-occurrence records, not local invertebrate surveys.

Through the year
0–3 scale · October highlighted
J
F
M
A
M
J
J
A
S
O
N
D
Trout seasonSeason
1
2
2
2
1
SulphurHatch
2
3
2
Trico (Eastern)Hatch
2
3
3
2
Eastern Blue-Winged OliveHatch
2
3
3
3
3
3
3
3
2
Eastern Summer BWO (Drunella)Hatch
2
3
3
2

Numbers are intensity 0 (none) to 3 (peak) — a guide, not a guarantee.

Ranked for today
Brown Trout fly box
PL
Pass Lake
8-12 · Pattern
Proven pattern for this period
Local fly shops: Driftless Angler
Permits & access
Permit required — see local rules.
  • WI DNR — special regulations on parts of the creek; verify.
What's coming
Plan ahead
5-day outlook
Fishing better nearby · 5
Bloody Run Creek
57 km
84
Brown trout · Rainbow trout
Blue River
6.0 km
0
Brown trout · Rainbow trout
Big Green River
19 km
0
Brown trout · Rainbow trout
Willow Creek
38 km
0
Brown trout · Brook trout
Tainter Creek
48 km
0
Brown trout · Brook trout
Gallery · 2
  1. A fly fishing line stretched over Castle Rock Creek in the Wisconsin driftless area, backlit by evening sun through streamside trees.
    Fly Fishing School, Fennimore, WI, Castle Rock Creek
  2. Terrain map of the venue
    Terrain map
About this water

A spring creek of the chalk-stream kind — weed-trailing, alkaline, absurdly productive — with a reputation for big browns that didn't get big by being stupid. Grant County's limestone country makes the water hard and fertile, and the fish behave accordingly. This is fine-tippet, watch-the-rise-form fishing.

  • Limestone
Water quality · US Clean Water Act
  • Aquatic life: Impaired
What this classification means

EPA ATTAINS assessment unit 'Castle Rock Creek' (WI10002572), 2024 Integrated Report. Aquatic Life use: Not Supporting. Listed impairment causes: Nutrients, Turbidity. This is a Clean Water Act assessment-unit classification (the US analogue of WFD), not a live reading.

Status is for the Clean Water Act assessment unit covering this reach.

EPA ATTAINS (Clean Water Act) · WI10002572

The full read · show the working · for Brown Trout · confidence 90%
How the 0 is built — score × weight = contribution
Temperature100 × 28%28.0
Flow80 × 22%17.6
Clarity95 × 18%17.1
Feeding Time55 × 13%7.2
Pressure80 × 7%5.6
Insect activity55 × 12%6.6
Conditions total= 82
Can you trust it?
Water temperatureair-to-water estimateestimated
Level / flowproxy via Bloody Run Creekproxy
Prey activitymodelled from regional profilemodelled
What would change the calculation
The dawn and dusk windows score higher than the midday lull.
Directions
Apple MapsGoogle Maps
Seasons & zones
  • Trout First Saturday in January (early catch-and-release, artificial only) → October 15 (regular harvest season from first Saturday in May)
Related guides
Euro Nymphingsubsurface methods
Booking & contacts