Missouri | Missouri Ozarks
Big River
Mammoth Access to Merrill Horse Access
Check current paddling conditions for this Big River route, including water level, recent gauge trend, weather, and route details.
Route snapshot
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Today
Get the answer fast, then scan the route.
Start with the verdict, current conditions, route plan, and quick facts before you commit to the drive.
Today's conditions
Gauge
Recent trend
Checking preferred range.
Checking trend.
Gauge source
--Checking timestampMN DNR provides the current paddling level here, but not chart-ready recent samples.
Weather
Best window today
Checking weather.
Today by hour
Short-route forecast
Checking the next several hours.
Quick facts
Plan
Dial in the shuttle, distance, and access.
Use this section once the route looks viable and you need to turn it into an actual trip plan.
Access plan
Access, shuttle, and map
Launch at MDC Mammoth Access and take out at MDC Merrill Horse Access for a 5.4-mile Big River day west of De Soto. Use the Richwoods USGS gauge as the direct corridor gauge and skip this route when it is above the local high-water cutoff.
Put-in
Mammoth AccessOpen mapMammoth and Merrill Horse are MDC public access areas, but posted signs, road conditions, parking areas, and area maps control exact use.
Take-out
Merrill Horse Access / Highway H bridgeOpen mapThe Mammoth coordinate is a public paddling-location coordinate paired with MDC access confirmation; the Merrill Horse coordinate uses the USGS Richwoods / Highway H gauge corridor as the practical take-out anchor. Follow on-site signs for the actual ramp or landing.
Pulling access map tiles. Usually under 5 seconds.
Access caveats and watch for
Access caveats
- Mammoth and Merrill Horse are MDC public access areas, but posted signs, road conditions, parking areas, and area maps control exact use.
- The Mammoth coordinate is a public paddling-location coordinate paired with MDC access confirmation; the Merrill Horse coordinate uses the USGS Richwoods / Highway H gauge corridor as the practical take-out anchor. Follow on-site signs for the actual ramp or landing.
- The app uses community threshold guidance from OzarkAnglers, not an official MDC paddling band. Make a same-day visual call before committing.
Watch for
- Scraping and shallow riffles when the Richwoods gauge is near or below 100 cfs.
- High or rising water above about 800 cfs, with strong current, muddy water, floating wood, and harder landings.
- Flows over 1,200 cfs at Richwoods; local guidance calls this section too high.
- Anglers, jetboats or small motorboats, gravel bars, wooded bends, root wads, strainers, and private banks away from public accesses.
Route gallery
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Sources
Check the data behind today's call.
Use this section when the page shows stale data, limited confidence, or a call you want to verify before driving.
Why this scoreToday's data confidence is checking
Data confidence mostly comes down to three things: how direct the gauge is, how clear the range is, and how fresh the data is.
- Checking data confidence notes.
- Checking data confidence cautions.
OutlookTomorrow and weekend
This is a cautious early look. If the data is too thin, we leave it out.
Waiting on forecast.
Waiting on forecast.
Data behind the scoreGauge, thresholds, and timing
These are the live readings and threshold notes behind today's score.
| Gauge site | Big River near Richwoods, MO |
| Discharge | Checking |
| Gauge height | Checking |
| 24h trend | Checking |
| 24h change | Checking |
| Current band | Checking |
| Rain last 24h | Checking |
| Rain last 72h | Checking |
| Air temp | Checking |
| Water temp | Checking |
| Wind | Checking |
| Gusts | Checking |
| Rain timing | Checking |
| Target band | 100 cfs to 800 cfs |
| Low threshold | 100 cfs |
| High threshold | 1,200 cfs |
| Data confidence behind the range | Local route guidance |
| Gauge observed | Checking |
| Paddle Today updated | Checking |
| Main source behind this score | OzarkAnglers Big River section guidance for the Richwoods gauge |
| Gauge source | Checking |
| Weather source | Checking |
| Rainfall source | Checking |
NotesWhat to know before you go
These notes cover the access details, route quirks, and source caveats most likely to matter once you get there.
- Public put-inMDC Mammoth Access
MDC says Mammoth Access is on the Big River, was acquired to provide better public access, and is 5.40 river miles upstream from Merrill Horse Access and the Route H bridge.
- Public take-outMDC Merrill Horse Access
MDC says Merrill Horse Access is on the Big River, 5.40 river miles downstream from Mammoth Access and 5.30 miles upstream from Browns Ford Access, with public department-area boat-use rules.
- Route shapeMammoth to Merrill Horse, 5.4 miles
OzarkAnglers lists Mammoth MDC Access at mile 0.0 and Merrill Horse MDC Access at mile 5.4 for this Big River section. MDC independently gives the same spacing.
- Direct live gaugeUSGS 07018100
USGS Big River near Richwoods showed same-day June 1, 2026 values of 1,490 cfs and 5.76 ft at 07:00 CDT during review.
- Gauge fitRichwoods / Highway H corridor
OzarkAnglers identifies the Richwoods gauge as the reliable gauge for the Mammoth / Merrill Horse section. USGS site metadata places the gauge at 38.159611, -90.706056, effectively in the Merrill Horse / Highway H take-out corridor.
- Threshold bands100-800 cfs ordinary float window, 1,200 cfs too high
OzarkAnglers describes under 100 cfs as low but floatable with scraping, 100-800 cfs as floatable, 800-1,200 cfs as very high and dangerous for inexperienced paddlers, and over 1,200 cfs as too high.
Verify it yourselfCheck the source links
Use these links to double-check the gauge, route details, and access notes before you head out.
Paddler reports
Recent notes from paddlers
A few quick notes from people who were on this route recently.
Reports
Photos, paddler notes, and updates.
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More routes to check next
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Quick answers
Big River paddling FAQ
What water level is good for paddling Big River?
Paddle Today watches Big River near Richwoods, MO and treats 100 cfs to 800 cfs as the target band for this route, with weather and recent trend included in the final score.
Where does this Big River route start and end?
This route starts at Mammoth Access and ends at Merrill Horse Access / Highway H bridge, about About 5.4 mi on the water.
Is this Big River route good for beginners?
This is listed as an easy route, but conditions still matter. Check today's score, water level, weather, and access notes before you go.
Flag a change
See something outdated?
Access, hazards, wood, and shuttle details change. Send a quick correction if something looks off.