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Direct and Indirect Effects Analysis

Last Page Update: July 29, 2010


  1. Match the scope and detail of the Affected Environment and Environmental Consequences chapters.
  2. Use resource analysis indicators to quantify affected environment descriptions and environmental consequences assessments.
  3. Make reasonable assumptions for your analysis.
  4. Provide a solid rationale for your assumptions and methodology.
  5. Document your assumptions and rationale for the affected environment and environmental consequences.
  6. Stay away from qualitative measurements (e.g. minor, major, significant)
Key Elements (Sequential Steps to Analyze Impacts)
  1. Summarize factors/elements that would cause the impact.– (“This alternative would close 2,500 acres to OHV use”);
  2. Describe the impact qualitatively, including appropriate linkages and consequences of the action.– (“Closing land to OHVs typically improves vegetation condition by eliminating vegetation crushing caused by vehicles”).
  3. Quantify the level of impact (severity) using the appropriate indicator.– (“This would protect 1,000 acres of sagebrush steppe and 1,500 acres of salt desert shrub habitat.”);
  4. Describe the context of the impact in relation to the existing condition described in the Affected Environment, using the appropriate indicator.– (“This 2 500 acres represents 30% of the ( 2,500 available sagebrush steppe and salt desert shrub in the study area.”);
  5. Compare impacts in the action alternatives to the impacts in the No Action alternative and the other action alternatives.– (“This would protect 500 more acres of sagebrush steppe and 1,000 more acres of salt desert shrub than the No Action alternative”).
  6. Don’t forget the “so what” . . . that is, provide the analytical conclusion interpreting the results, especially when you are unable to quantify the data– (“Therefore under Alternative X, this would maintain the connectivity between two large patches of habitat for shrub dependent species”).
Note: Provide supportable data if possible.
Example 1:
The proposed project would affect 25 acres of the existing acres of gray wolf habitat found in the project area.  This represents 10 percent of the available gray wolf habitat in the project area and 1 percent of the 2,560 acres of gray wolf habitat found within the state. Currently, there is an estimated 100 wolves using this regional habitat; therefore, assuming the current wolf population represents carrying capacity of this habitat, the loss of 256 acres of habitat would essentially represent the amount of habitat necessary to support approximately 1 percent of that population, or 1 wolf. Given the reproductive and mortality rates, loss of 1 wolf would not be expected to alter the population dynamics and therefore wouldn’t affect the population as a whole.
Example 2:
The proposed project would remove approximately 100 acres of vegetation throughout Coyote Basin over the next 10 years. As described in Chapter 3, this area is managed as VRM Class II. The removal of vegetation and placement of oil wells would result in bare ground, creating visual contrasts with surrounding vegetation.
Additionally, the wells are non‚Äźnatural structures that would be in the foreground of two key observation points which are often used by recreationists. These impacts would be inconsistent with the current management objectives for VRM Class II, consequently resulting in an adverse impact to visual resources in the project area.