Yeah but no Stillwater nearby.Looks like Callibaetis with those speckled wings.
Ah yes thanks. The mottled wings on the bug I shot (same bug both photos) had me second guessing life stage. But they are clear and mottled I suppose.Just for reference, here are pictures of a Callibaetis dun (subimago) and a spinner (imago). Typical of all mayflies, the wings of the dun are translucent, as opposed to the clear (hyaline) wings of the spinner. The spinner also has much longer tails than the dun