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Generated foothill canyon creek scene representing North St. Vrain below Button Rock Reservoir
All Colorado reports

North St. Vrain

Generated artwork: BlueStreamFly · Regional illustration; not the exact location.

Should I go fishing?

Check before you go.

Best option: Floating. A float is in play where this report supports boat access and wind, releases, and shuttle logistics are manageable.

Check first: No structured live flow

Rating updatedRiver local time:

Why this recommendation?

RiverReports is linked for the flow chart, but this page does not have a structured live flow value the score can read automatically. Treat the rating as conservative and open the chart before committing.

Available live dataMediumHow much of the live flow, weather, and alert data came back.
Confidence in this recommendationLowNo structured live flow
Sources checked often

If you go

Check first
Use RiverReports for quick flow context, then match the day to Button Rock Preserve access rules and the forecast.
Try
Fish the first good-looking water you can reach legally because the creek near the entrance can be as useful as farther walk-in sections.
Leave when
Skip when the preserve lot is full, summer heat is building, or the creek is too pushy to fish from safe edge positions.

Flow and weather

Showing server-checked river conditions while current readings refresh.
Flow
—
Live flow is not available here.
Air forecast
62°F
Next 24h high
75.0°F

NWS air forecast near

Rain chance
2%

This is an air forecast, not a river-temperature reading. Check the water with a stream thermometer before fishing in hot weather.

Latest stored weather check

Mostly Clear

Wind
7 mph
Weather checked
More forecast and source details

Mostly Clear

National Weather Service

North St. Vrain below Button Rock forecast point

The National Weather Service forecast is temporarily unavailable.

Live data

Where these readings come from

RiverReports gauge: North St. Vrain below Button Rock Reservoir

RiverReports gauge Opens in a new tab.Official NWS forecast Opens in a new tab.

Flies for this time of year

Seasonal starting points, not a live hatch report. Match what you see on the water.

See flies for every season
SeasonWhat to look forFlies to try

Each fly name opens its matching Fly Box guide.

More fishing tips

Methods, fish species and trip notes

How to fish North St. Vrain today.

Late spring after runoff begins settling, summer mornings, and early fall are usually the best planning windows. Preserve crowding and exposed sunny afternoons can narrow the useful fishing window faster than the map suggests.

Low clear water

Use fine tippet, stay low, and fish smaller dries or light droppers along seams and banks.

Moderate stable flow

Best all-around condition for dry-dropper fishing and short nymph drifts.

High or pushy flow

Treat the creek as a bank-first scouting day or move to a safer backup if footing disappears.

Hot sunny afternoons

Fish early, monitor temperature, and shorten handling on pressured Front Range trout water.

Wading, bank fishing or floating?
Best access methodFloating

These scores compare the risks of wading, bank fishing, and floating.

Wading44/100

Wading is in play only where your chosen access has clear footing, legal entry, and no forced crossings.

Bank fishingNot recommended

This report does not recommend bank fishing on this reach.

Floating · Best fit46/100

A float is in play where this report supports boat access and wind, releases, and shuttle logistics are manageable.

Full river report

Is North St. Vrain worth the trip today? Check flow, weather, hatches, access, and rules for Colorado before you go.

The North St. Vrain below Button Rock is most useful when you treat it as a walk-in creek with clear access boundaries, pressure-aware presentations, and a backup option if the preserve is busy or the water is running too hard.

Fishing words used on this page
Cubic feet per second (cfs)
Cubic feet per second, or cfs, shows how much water passes the gauge each second.
Nymph
A nymph is a young water insect. Anglers also use the word for a fly that copies it.
Presentation
Presentation means how you cast and move the fly so it looks natural to a fish.
Seam
A seam is the line where fast and slow water meet.
Blue-winged olive (BWO)
Blue-winged olives, or BWOs, are small mayflies that often hatch in cool or cloudy weather.
Caddis
Caddis are small water insects. The adults look a little like tiny moths.
Dry-dropper
A dry-dropper rig has a floating fly with an underwater fly tied below it.
Emerger
An emerger copies an insect as it rises from below the water toward the surface.
Midge
Midges are tiny flies and a common trout food, especially in cold water.
Pale morning dun (PMD)
Pale morning duns, or PMDs, are light-colored mayflies that often hatch in warmer months.
Why this call

Why this score

FlowUse caution

RiverReports is linked for the flow chart, but this page does not have a structured live flow value the score can read automatically. Treat the rating as conservative and open the chart before committing.

Best mode nowUse caution

Float: A float is in play where this report supports boat access and wind, releases, and shuttle logistics are manageable.

SeasonHelps

Early fall: Often the best mix of cool nights, stable flow, and slightly lighter hiking traffic.

WeatherHelps

The current NWS air forecast is about 62F, and the next 24-hour high reaches about 75F. Mostly Clear.

Public alertsHelps

No active NWS alert was returned for this forecast point.

Trip notes

Check these before you choose a reach.

Best flows

Stable clear flows that leave seams and bank pockets readable without forcing aggressive crossings.

When to leave

Skip when the preserve lot is full, summer heat is building, or the creek is too pushy to fish from safe edge positions.

Local plan

Get there early, fish creek water near the entrance first, decide whether the walk farther in is earning value, and keep Big Thompson or Boulder Creek ready as backups.

Backup water

Big Thompson, Cache La Poudre, or Boulder Creek are better pivots when Button Rock access, heat, or crowds narrow the day.

North St. Vrain access and rules.

Use these places as starting points. Open the access link below and check posted signs before you park or enter.

Before you go

A Colorado fishing license is required, and the City of Longmont notes that Ralph Price Reservoir also requires a separate special permit with its own season and tackle rules. Review both the Colorado brochure and the preserve rules before you fish.

Where to access the river

Button Rock Preserve entrance and fishing pier

Best official starting point for creek access and preserve orientation.

Longmont Reservoir side of the preserve

Useful for nearby walk-in water and mixed preserve scouting close to the entrance.

Ralph Price Reservoir approach

A two-mile hike and a separate permit context if you choose the reservoir instead of the creek.

  • Button Rock is walk-in only beyond the gate, and the parking lot can close when it fills.
  • Creek fishing and Ralph Price Reservoir fishing are not the same plan. The reservoir has a separate permit structure and season.
  • Preserve closures and habitat-protection areas matter as much as the flow chart when choosing how far to walk.

If this water does not fit the day, check another report before you start the drive.

ColoradoBig Thompson fishing reportA nearby Front Range alternative when Button Rock access is crowded or limited.ColoradoCache La Poudre River fishing reportA larger freestone backup when you want more room or stronger flow variety.ColoradoBoulder Creek fishing reportA closer fallback for short technical sessions if the preserve lot is full.
See all Colorado fly fishing reports

Sources and report details

Official agencies and primary river operators come first. Secondary tools are labeled so you know what carries the most weight.

Rules and closures

Check what is allowed, where the rule applies, and whether the river is open.

Flow and weather

Check the latest river reading and forecast before you leave.

Access and land

Check public entry points, land rules, and seasonal access changes.

See all 7 checked sources

Rules and closures

Check what is allowed, where the rule applies, and whether the river is open.

Flow and weather

Check the latest river reading and forecast before you leave.

Access and land

Check public entry points, land rules, and seasonal access changes.

Source check is old. Last checked . Open the official links now and check for changes.

See something wrong? Report a source problem. Please do not send private spots or private access notes.

How this report was checked

How this report was checked

Trip guidance checked

What was checked: This report uses official regulation, flow, weather, access, and public-land sources first, then adds practical planning guidance for fly anglers.

Live measurements and forecasts keep their provider timestamps. Rules, access, and trip guidance use the source-review date shown here. BlueStreamFly planning advice is editorial interpretation, not an agency notice.

First-hand experience: BlueStreamFly does not claim a first-hand visit or local field test for this report unless a real contributor is explicitly named and linked.

Quick questions

Do I need a special permit to fish the creek?

For the creek, start with a valid Colorado fishing license. The separate special permit applies to Ralph Price Reservoir inside Button Rock Preserve.

Is the best fishing far inside the preserve?

Not always. Water close to the entrance can fish well, especially when you can work it quietly before foot traffic builds.

What is the biggest planning mistake here?

Mixing up preserve access rules, reservoir permit rules, and creek strategy. Sort those out before you choose flies.