In California, beaver (Castor canadensis) were first recognized for their value as a furbearer. Additionally, in many areas, beaver are considered desirable if not essential components of stream and wetland ecosystems. Where beaver and human activity overlap, beaver have become nuisance animals causing direct damage through dam building, flooding, bank denning, and loss of agricultural crops. Other problems such as the threat of levee failure and subsequent flooding, increases in undesirable brush growth due to a raised water table, restricted access due to flooding, and an increased mosquito population resulted in the Department of Water Resources (DWR) developing a beaver management program. In 1984, DWR entered into a long-term agreement with the U.S. Department of Agriculture (USDA) Animal Damage Control (ADC) program to eliminate a large existing population of beaver and remove subsequent reinvading individuals from a 20-mile stretch of man-made Cherokee Canal in Butte County, California. In addition, existing dams, lodges, dens, and heavy brush growth were removed in an attempt to insure the flood safety of the project and modify the existing habitat making it less suitable for reinvading beavers. Both the costs and results of this program are discussed, as well as the long-term management strategy for this project

Manipulation or alteration of habitat vegetation is used frequently with integrated pest management of certain vertebrate pest species. However, it has been less than satisfactory with ground squirrel species in many situations. Special plantings of tall grasses and broadleaf species were experimentally explored in an effort to make levee habitat less suitable for the California ground squirrel in the Sacramento Valley. The experimental plantings failed to achieve that objective for a variety of apparent or suspected reasons and, in fact, in some grass plots the number of ground squirrels increased over what was present prior to planting. Other problems associated with these experimental plantings, including aggressive tendencies of some species, are discussed.