2. Once the riffle has been located, select an area measuring 3 feet by 3 feet which is typical of the riffle as a whole. Avoid disturbing the stream bed above this area, so as not to alter the sample.
3. Prior to entering the stream, examine the net closely. Remove any organisms that might remain from the last time the net was used.
4. DO NOT STAND IN THE SAMPLING AREA
5. Have one person place the net at the downstream edge of the sampling area. The net should be held perpendicular to the flow, but at a slight downstream angle. Stretch the net to approximately three feet, but be certain that the bottom edge is Iying firmly against the bed. If water washes beneath or over the net you will lose organisms.
6. STAND BESIDE, NOT WITHIN THE SAMPLING AREA! Place one foot at the upstream edge of the area as a marker. Remove all stones and other objects two Inches or more in diameter from the sampling area. Hold each one in front of the net and below the water surface as you brush all organisms from the rock surface. Before placing each rock outside the sampling area, examine the surface to be certain you have not missed any organisms.
7. When all materials two inches or larger have been brushed, step into the upstream edge of the sampling area and kick the stream bed vigorously for exactly sixty seconds. Kick from the upstream edge towards the net so that when sixty seconds are up you will have just reached the seine. Try to disturb the bed to a depth of at least two inches.
8. Once Step 7 is completed, carefully remove the net with a forward scooping motion. DO NOT allow water to flow over the top of the net or you may lose organisms.
9. Carry the seine to a flat and clean area on the stream bank. Remove leaves, rocks, and other debris. Examine for any attached organisms. Using fingers or forceps, remove the larger organisms from the net and place in the plastic container with water for later identification. Examine the smaller organisms that remain on the net.
10. Record the presence of each type of organism collected and give an estimate of the number of each type using the appropriate letter code on the stream quality assessment form.
11. Go to the edge of the stream; turn over rocks to see if you observe any additional macroinvertebrates that you have not already collected in the seine.
12. If time permits, take another collection in a different area of the same riffle.
13. Consolidate all the collections made on the same day at each individual station to obtain a cumulative index value that will best represent all the taxa present.
14. Determine the stream quality assessment using the procedures listed before.