BirdTrout
South Branch Au Sable River, Michigan
52 mapped river miles, draining 385 square miles across Crawford, Roscommon counties, in the Au Sable River watershed. A USGS gauge stands in it, but its record is too short for a measured July mean, so what this page knows about its temperature is today's reading and MDNR's classification of the water itself.
50°F and colder is cold, through cold-transitional and cool, to warm above 70°F — the same four bands, breaking at 58, 64 and 70°F, that the app paints. Grey is water nobody has measured.
The nearest live reading
The nearest gauge is 8.1 miles away, at South Branch Au Sable River Near Luzerne — not a reading of this water, but of what the region is doing today. A closer gauge has stopped reporting — it has sent no water temperature for 1431 days, since 28 October 2022, so no number here comes from it.
The pills above go to USGS. These are this site's pages for the same gauges — a thirty-day chart, the monthly means, the record, and today's reading against the five-year normal for today: 04135687.
The character of the water
Fifty-one and a half mapped miles through Crawford and Roscommon counties, draining 385.33 square miles, with 20 access sites, 15 of them walk-in and 5 launches, by far the most developed access in this watershed. Twenty and nine tenths miles carry blue ribbon designation from Roscommon down to the Main Branch, and 18.6 miles fall under Type 1 regulations, last Saturday in April through September 30th, five fish with no more than three trout 15 inches or greater. A 2022 survey in Crawford County under gear-restricted regulation, mean width 63.6 feet, returned 626 trout per acre and 39 pounds per acre, brook and brown trout. Median mapped width is 33.0 feet. MDNR types 12.6 miles, 24 percent: cool through the middle river, cold-transitional for 4.5 miles from river mile 11.1 to the mouth. Those classes describe the valley segment, not the water, and no measured temperature exists; the gauge at Chase Bridge carries no July mean.
Thermal classification
MDNR types this water from its valley, not from a thermometer in it. A class, not a temperature — no July mean, because none was measured here.
| Reach | Typed miles | Band | MDNR type |
|---|---|---|---|
| RM 46.9–25.6 | 7.6 | cool | Warm transitional stream · very low gradient |
| RM 25.6–25.6 | 0.0 | cold-transitional | Cold transitional stream · low gradient |
| RM 25.4–21.9 | 0.5 | cool | Warm transitional small river · very low gradient |
| RM 11.1–0.0 | 4.5 | cold-transitional | Cold transitional large river · very low gradient |
MDNR has classified 12.6 of the 52 miles NHD carries for this stream — 24% of it. The typed water splits 8.1 mi cool, 4.5 mi cold-transitional. The untyped reaches are not warm water — they are water MDNR's inventory does not reach, and the mile ranges above span only the reaches it does.
Named stretches
Anglers name parts of this river. These are the names two or more independent sources use; each page says which sources, because a nickname is the one thing on this site that is not a measurement.
- Mason Tract — The South Branch through the 4,493 acres George Mason's heirs left to the state on the condition it stay wild. Ten-odd miles of flies-only, no-kill water with no development on either bank.
Questions about this river
- South Branch Au Sable River fishing report — what it reads right now
- When to fish the South Branch Au Sable River — hatches, seasons and temperature
- How to get to the South Branch Au Sable River — access, parking and public land
- South Branch Au Sable River fishing regulations — season, size and gear by reach
- Is the South Branch Au Sable River good for brook trout?
- Is the South Branch Au Sable River good for brown trout?
- Is the South Branch Au Sable River good for rainbow trout?
Regulations
MDNR trout stream types, as designated. Types on file cover 18.6 of the 51.6 mapped miles; 33.0 miles carry no type in this dataset. Always check the current Michigan Fishing Guide before you fish — this is a copy, and the Guide is the rule.
| Type | Where | Season | Minimum sizes |
|---|---|---|---|
|
Type 1 18.6 mi |
RM 35.3–15.8 | Last Saturday in April–September 30th | Brook trout 7", Brown trout 8", Rainbow trout / steelhead 10", Lake trout 10", Chinook salmon 10", Coho salmon 10", Pink salmon 10", Atlantic salmon 10" |
Creel across all types: 5 fish, with no more than 3 trout 15“ or greater. Zero (0) Arctic Grayling. Tackle: Artificial lures and all types of natural bait may be used.
Blue Ribbon. South Branch AuSable River (BR 17), 20.9 mapped miles. MDNR's limits, verbatim — upstream: Roscommon; downstream: Main Branch AuSable.
Access
20 mapped MDNR access sites within a quarter mile of the water, upstream first: Meads Landing (RM 20.3), Steckert Bridge (RM 18.3), South Branch Au Sable River Deerheart Valley Road Ending (RM 16.9), Chase Bridge (RM 15.8), South Branch Au Sable River Potters Landing (RM 14.9), South Branch Au Sable River Forest Rest (RM 14.8), South Branch Au Sable River Swamp (RM 13.8), South Branch Au Sable River Durants Hangar (RM 12.9), and 12 more. 15 walk-in, 5 boat or canoe launches.
Public land on the river
9 units of public or open-access land touch this river, 208,539 acres in total. Acreage is the whole unit, not the part beside the water.
| Unit | Owner | Acres |
|---|---|---|
| Roscommon Management Unit | Michigan DNR | 103,956 |
| Au Sable State Forest - Grayling Unit | Michigan Department of Natural Resources | 89,732 |
| Au Sable State Forest - Roscommon Unit | Michigan Department of Natural Resources | 8,044 |
| Forest Fire Experimental Station | Michigan DNR | 5,278 |
| Tisdale Triangle | Michignan DNR | 1,493 |
| Local Forest | County | 34 |
| Meads Landing | Michigan Department of Natural Resources | 2 |
| Steckert Bridge River Access | Michigan Department of Natural Resources | 1 |
| Wallace Park | — | 1 |
Species
MDNR's most recent survey on this river ran in 2022 at South Branch Au Sable River, Crawford County, in a channel averaging 63.6 feet: brook trout, brown trout, at 626 trout per acre and 39 pounds per acre. MDNR strata: medium, land-locked, wild trout; regulation at the station, gear restricted.The station has been surveyed in 38 years since 1972.
Stocked, per the MDNR record: Brook trout, Brown trout, Rainbow trout. The most recent plants are Rainbow trout at Private Pond - Dewitt Trail (Crawford Co., through 2018); Brown trout at South Branch Au Sable River - Roscommon County (Roscommon Co., through 2015); Brook trout at S Br Ausable River (Crawford Co., through 1986).
Hatches on this water
53 insects are recorded from northern lower Michigan, which is the region this river sits in. That is a claim about the region and not a survey of this stream: nobody has recorded which of them has been caught here. Open the river in the app and the hatch panel will narrow it to the ones whose temperature window today's reading is inside.
| Insect | Peak | Water | Size |
|---|---|---|---|
| Fish Eggs Other |
October–January and April | 33–60°F | #10–16 |
| Little Black Stonefly Allocapnia / Capnia spp. |
January–April | 34–46°F | #16–18 |
| Little Brown Stonefly Taeniopteryx / Strophopteryx spp. |
February–April | 38–50°F | #12–16 |
| Blue-Winged Olive Baetis spp. |
March–May and September–November | 38–58°F | #16–22 |
| Blackfly Simulium spp. |
April–June | 40–65°F | #18–22 |
| Blue Quill Paraleptophlebia adoptiva |
April–May | 44–56°F | #16–18 |
| Cranefly Tipula spp. |
April–June and September–October | 40–65°F | #6–10 |
| Grannom Brachycentrus spp. |
April–May | 48–58°F | #14–16 |
| Green Rock Worm / Green Weenie Rhyacophila spp. |
April–June and September–October | 45–68°F | #10–14 |
| Hendrickson Ephemerella subvaria |
April–May | 45–58°F | #12–14 |
| Little Black Caddis Chimarra atterima |
April–May | 46–58°F | #16–20 |
| Alderfly Sialis spp. |
May–June | 52–66°F | #10–14 |
| Caterpillar Lepidoptera larvae |
May–September | 55–75°F | #8–14 |
| Crayfish Orconectes spp. |
May–October | 55–78°F | #4–8 |
And 39 more — the year-round records, mostly: midges, scuds and sculpins, which are in the water every day and are therefore never the news.
Tributaries and watershed
14 named streams meet this one. Confluence miles are above the mouth; the longest twelve are listed.
- Au Sable River 137.7 mi · RM 0.0
- Beaver Creek 20.3 mi · RM 20.6
- East Creek 7.2 mi · RM 35.3
- Hudson Creek 6.9 mi · RM 29.5
- Robinson Creek 6.9 mi · RM 22.1
- Cameron Creek 6.7 mi · RM 51.6
- South Creek 6.4 mi · RM 38.9
- Marsh Creek 5.9 mi · RM 47.4
- Thayer Creek 5.9 mi · RM 9.5
- Hickey Creek 4.8 mi · RM 14.6
- Douglas Creek 3.8 mi · RM 11.1
- Russell Creek 3.7 mi · RM 51.6
South Branch Au Sable River sits in HUC 8 04070007, the Au Sable River watershed, and drains 385 square miles, Strahler order 4 at the mouth. 77 NHD reaches carry the name for 51.5 miles in total.
Other water nearby
The closest 6 rivers on this site, straight-line from the middle of this one — not drive time.