Exploring up the Skykomish

Exploring up the Skykomish

By Troutnut on September 10th, 2020

I've been meaning to check out the scenic country headwaters of the Skykomish for a while, more for the scenery and variety than for the fish, which I expected to be mostly the same 6-12" rainbows and coastal cutthroats found in all the other rivers on the west slope of the Washington cascades. I was also looking to practice Euro nymphing some more, and the Foss River has some ideal stretches of pocket water for that. Starting late in the morning, I was successful early and often. Then, toward mid afternoon, the action shut down completely. I went from catching fish in every pocket to seeing no sign of them in extremely inviting pools. The water temperature was optimal, but the fish were just off.

For the last hour of daylight I drove to the South Fork Skykomish and fished a couple of promising pools. Fish finally started rising intensely right at dusk (to what, I'm not sure), and I caught six small rainbows on dries.

Throughout the day there were no noteworthy hatches, but I did find a couple of bugs worth photographing. I'm especially curious what a near-mature Ephemerellid nymph was doing in the river in mid-September, but I've not yet had time to put most of my recently collected specimens under the microscope and see what they are.

Photos by Troutnut from the Foss River and the South Fork Skykomish River in Washington

From the South Fork Skykomish River in Washington.

This logjam was a pretty serious obstacle moving upriver... the large log you see on the left is at least 3 feet in diameter. From the Foss River in Washington.

Closeup insects by Troutnut from the Foss River in Washington

Male Doroneuria baumanni (Golden Stone) Stonefly Adult

View 18 PicturesI found this stonefly on some streamside vegetation. I didn't see any in the air in several hours of fishing.

Collected September 10, 2020 from the Foss River in Washington
Added to Troutnut.com by Troutnut on September 19, 2020

Ephemerella aurivillii Mayfly Nymph

View 11 PicturesThis is a puzzling one to identify and I'm not sure about the species. The maxillary palp (

The palp on the maxilla of an Ephemerella nymph (detached and photographed under a microscope) is highlighted in red here.

Palp: A long, thin, often segmented appendage which can protrude from certain insect mouth parts such as the maxillae. Also known as the < />palpus.) is present and segmented, and the maxillary canines are not strongly serrate laterally. I think it's Ephemerella, not Serratella. The ventral (Ventral: Toward or on the bottom.) lamellae of the gills on abdominal segment 6 have a clear median notch with a depth at least half the length of the lamellae, which points toward a couple of uncommon species (most likely Ephemerella alleni), but the abdominal tubercles (

A few (not all) of the abdominal tubercles on this Ephemerella needhami nymph are circled. They are especially large in this species.

Tubercle: Various peculiar little bumps or projections on an insect. Their character is important for the identification of many kinds of insects, such as the nymphs of Ephemerellidae mayflies.) and coloration don't fit that species. To add to the confusion, none of the above species are expected to emerge in the fall, as far as I know. I'm going to call this one Ephemerella aurivillii for now, but that's highly uncertain.

Collected September 10, 2020 from the Foss River in Washington
Added to Troutnut.com by Troutnut on September 19, 2020

View 23 larger pictures»

Comments / replies

Martinlf	September 20th, 2020, 12:33 pm
Moderator Palmyra PA Posts: 3233	Looks like a fun day. Thanks for posting; I always enjoy seeing NW streams. My nephew lives near Portland, and, although we cancelled this year's tour, we are planning to fish together at least once a year after this one, fire and plague permitting.
	"He spread them a yard and a half. 'And every one that got away is this big.'" --Fred Chappell

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