Building a watershed health index

Fundamental ecological concepts are the foundation for each health index. Consistent steps are taken to progress from the identification of important ecological concepts to the delivery of a health index value by watershed:

Review scientific literature to inform the selection of significant and well-supported ecological relationships

Review availability of statewide GIS data that support the selected relationship.

Suitable GIS data must be:

  • Temporally stable
  • Likely to be repeated
  • Consistently collected statewide
  • Appropriate resolution for Major Watershed scale calculations

Discuss index development approaches with subject matter experts

Compute results by applying an appropriate GIS method, such as:

  • Advanced modeling techniques
  • Quantification of comparable values
  • Density of features

Rank and Score Results

  • Review results and range of values
  • Set threshold values for scores when available and appropriate
  • Assign "0-100" health scores based on the calculated range of values; or based on a range of known ecological conditions

Health Index Summary Table