Cosumnes River in California

DIY Guide to Fly Fishing the Cosumnes River in California

As one of the few rivers in the western Sierra without major dams, the Cosumnes River should be the classic example of a healthy watershed. Unfortunately, due to the invasive fish species present in the River and the pollution from illegal mining, the salmon and steelhead populations have been significantly reduced.

Thankfully, catchable rainbow trout are now stocked by the California Department of Fish and Game twice a year to supplement the native trout populations. You can still have luck catching trout in this fishery if you’re stealthy and careful.

Check out our guide so you have the best odds of successfully tackling the Cosumnes River in California.

Fly Fishing in Cosumnes River

The Cosumnes River is a 52.5 mile long river in northern California. The River gets its name from the Miwok language. The suffix “umne” means “people of.” The prefix is derived from the Miwok word “kosum” meaning “salmon.” Many locals pronounce the River’s name as “Consumnes,” even though there is no letter “n” in the first syllable. A local community college, Cosumnes River College, takes its name from the River. Their mascot is a Hawk, as a salute to the avian wildlife in the area.

The Cosumnes River flows from the Western slope of the Sierra Nevada mountains, and starts as three forks: the North, the Middle, and the South Fork. Near Mokelumne City, the River joins the Sacramento-San Joaquin River Delta. The River’s tributaries include Deer Creek, Big Canyon Creek, and Little Indian Creek. 

The River has been a subject of ongoing controversy. County officials have lobbied to construct flood-control dams on the water, but have been unsuccessful in their attempts. The California Office of Environmental Health Hazard Assessment has issued an advisory for fish caught from these waters. At this River, you’ll see brown, brook, and rainbow trout. Additionally, there is also steelhead and chinook salmon.

The Cosumnes River Map and Fishing Access Sites

DIY Fly Fishing Map

Click map icons to get directions to fishing spots, boat ramps and USGS stream flow data

Best Places to Fish the Cosumnes River

The Cosumnes River is straddled by Highway 50 to the North and Highway 88 to the South. Highway 50 provides the best access coming from Sacramento, and Highway 88 if coming from the Stockton area.

Access from Highway 50 and Highway 88 is via a network of secondary roads, and logging roads in the El Dorado National Forest. There are relatively few roads that cross the various forks of the Cosumnes, hence these access points see a lot of traffic and heavy fishing pressure. If you are willing to do some exploring on logging roads though you will be rewarded with some fine fishing for wild trout.

There are different regulations depending on which area of the River you choose to tackle, so be sure to check out the regulations on the California Department of Fish and Game website before making your visit.

Best Time to Fish the Cosumnes River

For the section of River east of Highway 49, the fishing season is from the last Saturday of April to November 15. The best time to visit is in the spring, but you might have better luck catching larger brown trout in the fall.

Hatches on the Consumes are typical of Sierra West Slopes streams. Brown and Golden stoneflies are active March through June, and are joined by Little Yellow Stones May through July.

Pale Morning Duns are they best mayfly hatch and come off April into July. October caddis are a reliable hatch in September and October.

Terrestrials are a staple of a trout’s diet July through September.

Fly Box – What You’ll Need

Here is list of general fly pattern recommendations for Cosumnes River:

  • Caddis (various) (#14-18)
  • Golden Stonefly (#6-10)
  • Salmon Fly (#4-6)
  • Ants (#14-16)
  • Beetles (#12-14)
  • Blue Winged Olives (#18-22)
  • Midges (various) (#18-22)
  • Little Yellow Stonefly (#14-16)
  • Grasshoppers (#10-12)
  • October Caddis (#8-10)

Gear Recommendations

A 9-foot 5-wt fly rod with floating line is perfect for fishing dry flies and small nymphs on Cosumnes River. A tapered 9-foot leader, with tippet size 3X to 5X to match the flies you are throwing, is pretty standard.

Cosumnes River Fishing Report

There aren’t any area fly shops or guides (that I’m aware of) that are currently providing a Cosumnes River fly fishing report.

Fishing Regulations

The state of California requires that all people who are 16 years of age and older have a valid fishing license. There are resident and non-resident sport fishing licenses available. You can purchase a one-year, 10-day, two-day, or one-day license. Some areas also require a permit. You can purchase the license and learn about the most current regulations through the California Department of Fish and Wildlife.

Trip Planning Tips

The nearest airport to Cosumnes River in California is the Sacramento International Airport. You can travel to any major or municipal airport in California and arrive at your destination after a few hours of scenic driving.

If you are looking for lodging in the area, the Days Inn offers close proximity to the River and a continental breakfast. If you would rather experience the River up close and personal, you can stay at the Middle Fork Cosumnes Campground. They are open from Memorial Day weekend to mid September.

You just don’t see many free flowing rivers without major dams. The Cosumnes River is undeniably a special fishery, and efforts should continue to be made to preserve this beautiful natural wonder.

Feature image by US Fish and Wildlife Service

Looking for more places to fish? Check out our DIY Guide to Fly Fishing California


About the Author Ken Sperry

Ken is an avid fisherman of 40+ years who loves to explore and find new places to fish. He created DIY Fly Fishing to help you do the same.