The best app for checking river levels and water temperature for fly fishing
Every serious option here reads the same public USGS feed, so the raw numbers are not the differentiator — what separates them is how much interpretation they do for you, and whether they are built for anglers or for paddlers.
They all read the same data
Worth saying plainly up front: streamflow, gauge height and water temperature come from USGS Water Services, a free public feed. No app has privileged access to it. Anyone claiming exclusive river data is repackaging something you can read yourself — we explain how on our USGS gauge lookup page. So the honest question is not who has the data. It is what each one does with it.
The options
Snoflo
Strong, data-forward coverage of USGS gauges with streamflow reporting and percent-of-normal context, including water temperature. Leans toward climate and snowpack intelligence across outdoor recreation generally rather than fishing specifically. Good if you want the raw hydrology well presented.
RiverApp
Broad international coverage of river levels and flows with custom level alerts and whitewater section detail, plus water temperature where the station reports it. Its centre of gravity is paddling, so the framing is runnability rather than fishability.
onWater
Best known for float planning and access — put-ins, take-outs and river mileage. Most useful when the question is where to launch rather than whether conditions are right today.
Waderly
Built around the fishing decision rather than the measurement. It reads the same USGS gauges, then converts them into a verdict: whether flow is high, low or near normal for this date, whether water temperature has crossed the 68°F trout threshold, and what to do about it. It layers on NWS weather and flood alerts, barometric pressure trend, solunar feeding windows, tides, trout stocking schedules, wild trout designations, public land access and state regulations. Free, no ads, no account required.
What to actually compare
- Does it show water temperature, and does it tell you what that means? Several apps surface the number. Fewer state the consequence for trout.
- Is flow given context? 300 cfs means nothing alone. Against the historical median for this date it means everything.
- Is it built for anglers or paddlers? Runnable and fishable are different questions about the same river.
- How fresh is it, and does it say so? An explicit reading timestamp is the difference between live data and a cached number.
- What does it cost, and what is behind the paywall? Current conditions should not be a premium feature.
Our honest position
If you want raw hydrological data across outdoor recreation broadly, Snoflo is excellent. If you paddle as much as you fish, RiverApp’s alerting and whitewater detail are hard to beat. If your question is specifically “is this trout stream worth the drive this morning?”, that is the question Waderly is built to answer, and the one the others leave to you.
Try it on a water you know well and see whether the verdict matches your judgement: Tulpehocken Creek near Reading, PA, Penns Creek at Penns Creek, PA, Little Juniata River at Spruce Creek, PA.
Frequently asked questions
What is the best app for checking river levels for fly fishing?
It depends what you want. Snoflo is strong for raw hydrological data, RiverApp for level alerts and paddling detail, and Waderly for turning the same USGS readings into a fishing verdict including a 68°F trout temperature check, flow against the seasonal median, weather, stocking and regulations.
Do these apps use the same river data?
Largely yes. Streamflow, gauge height and water temperature come from the free public USGS Water Services feed. The differences are in coverage, presentation and how much interpretation each app adds.
Is Waderly free?
Yes. All gauge pages and live readings are free with no account. An optional Pro subscription adds a larger watchlist and automatic flow alerts.