1. Add a couple of inches of water to your main sorting tray and the others you will be using. Spread the sample out over the bottom of a white tray. Spend a little time watching the macroinvertebrates. See how they move and look at the different shapes and colors (the colors change when they are preserved).
2. Pick through your sample in the sorting tray. Use a pipette, tweezers, spoon or brush to transfer your macroinvertebrates to the wells in the ice cube tray, craft organizer or smaller tray. Place animals belonging to the same group in the same portions of the tray. In some cases it may be simpler to sort through one order at a time, especially if multiple kinds are probable. For example, Ephemeroptera (Mayflies), Plecoptera (Stoneflies) and Trichoptera (Caddisflies) also called the EPT’s, can be very abundant in healthy streams and these orders as well as Diptera (True flies) are likely to have multiple families present.
3. For the first 10–20 minutes, transfer any animal that you see from the sorting tray into the other trays. For the last 10–20 minutes, look particularly for animals that are uncommon. Fast moving macroinvertebrates will be obvious but some will only start to move after 10 minutes or so. If after 20 minutes you find an invertebrate you haven’t seen before, sort for another 10 minutes until you find no new families. Note: You should not spend more than 30-minutes sorting your macroinvertebrate collections.
4. Identify your collections: There are many key guides available to identify your macroinvertebrates. A 10x magnifying loupe, magni-cube or low power binocular microscope is useful for looking closely at the animals.
5. Estimate the abundance or count the number of each type of animal in the tray sections. As you look for families and count or estimate abundance keep track of your tallies on the survey data sheet. Use a pencil so you can erase or scratch though your numbers when different families are encountered or your abundance changes. If you find a macroinvertebrate you cannot identify, record this on your result sheet, giving a brief description of what you found. When you have finished, return the animals to the water, as close as possible to the collection site.