As a part of the Environmental Protection Agency (EPA) National Lakes Assessment, the Washington (State) Department of Ecology collected biological, chemical, and physical data at (30) randomly selected WA lakes during the summer of 2007. Among the physical data, (18,510) macroinvertebrate specimens were collected. Absent macroinvertebrate identification, which was still being performed by EPA at the time, in April of 2010, the WA Department of Ecology issued a report titled, An Assessment of Washington Lakes: National Lake Assessment Results. Having extreme interest in aquatic macroinvertebrate sampling of any kind, I contacted the WA Department of Ecology some (4+) months ago with the hope of getting access to statistical detail from the WA Lakes macroinvertebrate sampling. The WA Department of Ecology had not yet received those results back from EPA, so I was referred to the responsible EPA scientist, who has since graciously provided me with the macroinvertebrate sampling and identification results. A few years ago, I developed a North American Aquatic Insects database, which was most recently used to help summarize the (1,511) mostly genus level records I received from EPA into (77) family (or higher) level records. Each summary record lists the taxonomic name of the macroinvertebrate order, followed by a parenthesized common name for the macroinvertebrate family, and the total number of specimens collected: Diptera (Midge) 8047 Amphipoda (Scud) 3652 Haplotaxida (Freshwater Earthworm) 1399 Ephemeroptera (Small Squaregill Mayfly) 712 Isopoda (Aquatic Sowbug) 700 Veneroida (Peaclam) 529 Tricladida (Planarian) 508 Trombidiformes (Freshwater Mite) 489 Diptera (Biting Midge) 357 Basommatophora (Wheel Snail) 347 Odonata (Pond Damselfly) 341 Trichoptera (Longhorned Case Maker Caddisfly) 256 Ephemeroptera (Small Minnow Mayfly) 148 Basommatophora (Tadpole Snail) 116 Haplotaxida (Tubifex Worm) 115 Heterostropha (Valve Snail) 68 Coleoptera (Riffle Beetle) 62 Trichoptera (Purse Case Maker Caddisfly) 54 Haplotaxida (Freshwater Worm) 48 Haplotaxida (Freshwater Potworm) 39 Veneroida (Concentrical Clam) 35 Neotaenioglossa (Freshwater Snail) 34 Hoplonemertea (Ribbon Worm) 33 Arachnids (Spiders) 32 Rhynchobdellida (Freshwater Leech) 31 Trichoptera (Trumpet Net & Tube Maker Caddisfly) 28 Odonata (Skimmer or Emerald Dragonfly) 26 Heteroptera (Water Boatman) 26 Trichoptera (Long-Horn Caddisfly) 24 Basommatophora (Pond Snail) 22 Sarcoptiformes (Freshwater Mite) 21 Trichoptera (Lepidostomatid Case Maker Caddisfly) 20 Anthoathecatae (Hydra) 17 Megaloptera (Alderfly) 15 Basommatophora (Freshwater Limpet) 14 Odonata (Emerald Dragonfly) 11 Diptera (Phantom Midge) 10 Ephemeroptera (Pronggilled Mayfly) 10 Trichoptera (Giant Case Maker Caddisfly) 9 Trichoptera (Northern Case Maker Caddisfly) 8 Arhynchobdellida (Worm Leech) 7 Coleoptera (Predaceous Diving Beetle) 7 Odonata (Skimmer Dragonfly) 6 Heteroptera (Backswimmer) 6 Diptera (Shore Fly) 6 Odonata (Darner Dragonfly) 5 Canalipalpata (Freshwater Fanworm) 5 Trichoptera (Northern Casemaker Caddisfly) 4 Plecoptera (Slender Winter Stonefly) 4 Architaenioglossa (Valve Snail) 4 Plecoptera (Green Stonefly) 4 Decapoda (Freshwater Crab) 4 Lepidoptera (Grass Moth) 4 Ephemeroptera (Flatheaded Mayfly) 3 Ephemeroptera (Spiny Crawler Mayfly) 3 Diptera (Dance Fly) 3 Coleoptera (Crawling Water Beetle) 3 Diptera (True Fly) 2 Glossiphoniidae (Turtle/Snail Leech) 2 Basommatophora (Freshwater Snail) 2 Branchiobdellida (Freshwater Worm) 1 Unionoida (Freshwater Clam) 1 Coleoptera (Water Scavenger Beetle) 1 Diptera (Crane Fly) 1 Ephemeroptera (Common Burrower Mayfly) 1 Ephemeroptera (Pronggill Mayfly) 1 Gastropoda (Freshwater Snail) 1 Trichoptera (Caddisfly) 1 Rhynchobdellida (Turtle/Snail Leech) 1 Plecoptera (Spring Stonefly) 1 Lepidoptera (Aquatic Moth) 1 Odonata (Dragonfly) 1 Ephemeroptera (Primitive Minnow Mayfly) 1 Okay, so what relevance might this have for a flyfisher targeting trout in WA lakes? Well, since midges (Chironomids) were the most commonly collected, constituting 45.5% (8046 out of 18510) macroinvertebrates, it’s obvious why flyfishing with a Chironomid imitation might be as productive as it seems to be here in WA. However, I leave further observations for you to make, hoping this information may prove at least mildly interesting, and might even stimulate discussion from which we can all learn.