Adverse impacts result from projects that create visual contrast with the natural form, line, color, or texture of the landscape to the extent that it degrades the visual values of an area, which are documented in the visual resource inventory (see Chapter 3). The visual values recorded in the visual inventory form the baseline assessment of the quality of the visual landscape against which impacts from changes in management proposed under the management alternatives are measured. Adverse impacts can occur regardless of whether a resource development project meets an established visual objective. Adverse impacts are not limited to human-caused activity, as wildland fire or other natural phenomenon also can adversely affect visual values. If resource development creates little or no contrast with the natural form, line, color, and texture of the landscape in the area of development, little or no impact would result. Human activity may, in certain cases, create beneficial impacts to visual resources if the activity adds visual variety that is in harmony with the natural landscape.

Direct impacts to visual resources occur if the visual values of the landscape are diminished or enhanced through the creation of natural or human-caused contrast. Indirect impacts relate to the management of other resource values, in which specific actions may limit or increase visual contrast on the landscape. Actions on lands not administered by the BLM (regardless of ownership) can impact the visual values of the adjacent public lands.

For purposes of this analysis, short-term impacts are those that last up to 5 years before the visual impact is mitigated or removed. Long-term impacts are any impacts that affect visual resources for longer than 5 years, such as visual intrusions associated with the construction of wind turbines.