Water resources that are capable of supporting sufficiently large populations of higher vertebrates to result in nutrient or bacterial loading are often remote or of nutrient-poor composition, minimizing the likelihood of serving as sources of concern. However, certain species can potentially alter water quality. Waterfowl and beavers are species that can beneficially and detrimentally impact the waterways on which they depend. In nitrogen-saturated waters where waterfowl converge, their wastes can drive ammonia concentrations up causing algal mats that lead to exaggerated dissolved oxygen cycles. On the other hand, waterfowl are a vital part of the food chain.
Beavers flood small watersheds, killing trees and crops and causing excessive amounts of turbidity.
Yet, beaver ponds can remove nutrients and provide habitats for many types of wildlife, creating possibilities for sportfishing and hunting. Discouraging habitation in the initial stages may prove to be the key management practice. Most species colonize in mid-March to late summer with the exception of the Great Blue Heron and the Common Egret which stay throughout the year. According to Dusi et al , colonized swamps showed elevated levels of ammonia and organic nitrogen . The impact of the wading birds on the colonized swamp was so profound that ammonia content showed an increase of 2 to 10 times that of the uncolonized swamps nearby.