Purpose: To find out if fish spawning areas are becoming degraded with sand.
Materials:
Procedure:
Pick a site (or several sites) on your river where the velocities are between 1-2 feet/sec., and where the substrate (material on the bottom of the stream) is large gravel or small cobbles (about 1" diameter is optimal).
Place the hoop or steel band in three spots, equidistant across the width of the river.
Determine the size of the stone most prevalent within the hoop.
Pick up at least 10 stones of the dominant size within the hoop while looking carefully to see if they lie in a "bed" of sand or other sediment, and keeping a finger on the spot on the stone where it came out of the bed. (Usually you can feel the stone's embeddedness, because the periphyton - algae and associated microorganism that grow on submerged surfaces - will feel slippery where the stone is not embedded.)
Measure with a ruler and estimate the percentage of the stone that is embedded.
| place across river | dominant particle size (inches) | 10 stones within hoop - % embedded | average % embeddedness in hoop | |||||||||
| 25% | ||||||||||||
| 50% | ||||||||||||
| 75% | ||||||||||||
| total averages divided by 3 for AVERAGE EMBEDDEDNESS: | ||||||||||||