Step 4: Run Screening to Calculate Index Scores
After Step 3, users have defined their screening objective, selected subwatersheds to compare, selected indicators and weights and possibly customized the RPS Tool with new indicator data. Now users are ready to run a screening and calculate results. This page contains a description of the index scores that are generated by the RPS Tool.
On this page:
Ecological Index
The RPS Tool combines the Ecological Indicators selected for a screening into an Ecological Index score for each screened subwatershed that can range from 0 to 100. The Ecological Index is intended to characterize a gradient of present subwatershed condition among the screened subwatersheds.
Subwatersheds with higher values of Ecological Indicators will receive higher Ecological Index scores. In general, these subwatersheds are more likely to be healthier and contain environmental features which can support successful restoration and protection outcomes. However, the exact meaning of high versus low Ecological Index scores will vary by screening and depend on the specific Ecological Indicators selected. For example, for a screening that includes Ecological Indicators which only measure land cover characteristics, higher Ecological Index scores will correspond to better landscape conditions in a subwatershed and related watershed processes. For a screening that includes indicators of water chemistry and biological condition calculated from stream monitoring data, higher Ecological Index scores will correspond to better instream conditions in a subwatershed.
Stressor Index
The Stressor Indicators selected for a screening are combined into a Stressor Index score for each screened subwatershed that can range from 0 to 100. The Stressor Index is intended to summarize the presence and magnitude of risks to subwatershed and aquatic ecosystem health.
Subwatersheds with higher values of Stressor Indicators will receive higher Stressor Index scores. In general, these subwatersheds have greater presence of pollutant sources and other water quality threats and are at increased risk for degraded health. The exact meaning of high versus low Stressor Index scores will vary by screening and depend on the specific Stressor Indicators selected. For example, for a screening that includes Stressor Indicators which only measure existing sources of nutrient pollution, higher Stressor Index scores will correspond to greater prevalence of those pollutant sources in a subwatershed. For a screening that focuses on indicators of future threats (e.g., extreme weather, sea level rise, loss of natural lands), higher Stressor Index scores will correspond to greater vulnerability to those threats. When viewing the Stressor Index, remember that the gradient of scores will reflect only those stressors selected for the screening.
Social Index
The Social Indicators selected for a screening are combined into a Social Index score for each screened subwatershed that can range from 0 to 100. The Social Index is intended to characterize non-environmental factors that can still highly influence efforts to restore and protect waters and watersheds. These are not ecological traits linked to condition, nor are they stressors that degrade watershed health.
Subwatersheds with higher values of Social Indicators will receive higher Social Index scores. In general, these subwatersheds have societal attributes that can support successful restoration and protection outcomes. However, because of the wide variety of topics covered by Social Indicators, this may not be the case for all screenings. For example, a user might design a screening so that higher Social Index scores correspond to subwatersheds that lack historic investments in restoration or protection. These subwatersheds may not have existing coalitions of stakeholders to readily support successful outcomes but could still be important to a user interested in working in areas that have been previously overlooked.
Restoration and Protection Integrated Index
The RPI Index combines the Ecological, Stressor and Social Index scores into one overall score. It should not be considered the only output or even the main output of RPS – it is simply a fourth index alternative. Users that focus on the RPI Index alone might overlook important findings from Ecological, Stressor and Social Index scores.
The RPI Index is intended to highlight subwatersheds with a distinct combination of index scores. Subwatersheds with higher RPI Index scores have:
- Higher Ecological Index scores
- Lower Stressor Index scores
- Higher Social Index Scores
The combination of scores listed above generally corresponds to healthier subwatersheds with fewer stressors and more favorable social characteristics. This combination of scores was selected to help users identify subwatersheds that could require relatively lower effort to address water quality impairments and restore aquatic ecosystem integrity (e.g., the ‘low-hanging fruit’ for successful restoration). The RPI Index may be very relevant for some screenings and not applicable for others. Users that are not interested in subwatersheds with the combination of scores listed above can focus on the Ecological, Stressor and Social Index scores and not consider the RPI Index scores when viewing and interpreting screening results.