Park rangers can tell how clean rivers and ponds are by studying the creatures that live in the water. They count macroinvertebrates - animals with no backbones - that are large enough to see without a microscope or other tool. Snails, crayfish, and most insects are macroinvertebrates.
- Related Links
- Water Resources
- Water Quality at Glen Canyon NRA
- Rocky Mountain NP Water Quality
- Catoctin Mountain Park