Naiman et al. Beaver ponds may be favorable to the success of other introduced species. Beaver ponds may provide a refugia for introduced species which, without beaver ponds present, would probably be washed out of the river during the rainy season. This may give introduced species a foothold from which to invade the Santa Margarita River. Beaver dams may negatively affect trout migration.
Rainbow trout are native to the Santa Margarita River.
In a stream with several beaver ponds, the Rainbow trout might be at a disadvantage when competing with Brown Trout and Brook Trout. Beaver can have major impacts on their environment. Beaver activities can lead to many changes in water flow dynamics, species composition, nutrient cycling, carbon cycling and many other aspects of their surroundings. These effects may prove to be unfavorable in the rather delicate ecosystem of the Santa Margarita River in which beavers may negatively impact preservation or restoration efforts. References Unpublished account on the Santa Margarita River, 1970s.