Tiny Baetis mayflies are perhaps the most commonly encountered and imitated by anglers on all American trout streams due to their great abundance, widespread distribution, and trout-friendly emergence habits.
Some characteristics from the microscope images for the tentative species id: The postero-lateral projections are found only on segment 9, not segment 8. Based on the key in Jacobus et al. (2014), it appears to key to Neoleptophlebia adoptiva or Neoleptophlebia heteronea, same as this specimen with pretty different abdominal markings. However, distinguishing between those calls for comparing the lengths of the second and third segment of the labial palp, and this one (like the other one) only seems to have two segments. So I'm stuck on them both. It's likely that the fact that they're immature nymphs stymies identification in some important way.
I'm tentatively classifying this one as Dibusa angata because I cannot see any ocelli in my dorsal view of the head (and because it has a single spur on each front tibia). However, sometimes they can be difficult to spot when obscured behind setae in general, so I'm not 100 % sure on this one. If there are ocelli I missed, then based on ranges and colors the genus ought to be Stactobiella.