| Impact ID | 4221 |
| Impact Type | Habitat Alteration |
| Study Type | Observational |
| Study Location | Field |
| Impact Description | Due to the tendency of Phragmites australis to replace Typha/Scirpus reed marshes, muskrat dens, which were once plentiful under the native grasses, are now rare. |
| Reference | 23335 |
| Cost | |
| Location | Connecticut River, USA |