Using Watershed Health Scores

There are some 'Health Score Basics' that will help you understand and interpret the Watershed Health Scores. These include:

What is the range of scores for an index?  What do the colors mean?

A health score is a comparative index that synthesizes statewide ecological data into a single range of values. Health scores are calculated for all watersheds in Minnesota creating index values from 0 -100, red to green. health score bar, red to green, 0 to 100A score of 100 indicates the best condition or least amount of risk; a score of 0 indicates an unhealthy condition or the highest health risk. The data used for calculating the score must be available for the entire state with data collection likely to continue into the future. Comparing health scores can reveal parts of the ecological system that are functioning well and those that may be facing challenges.

What's the difference between a Health Index and a Health Metric?menu from WHAF map that shows the water quality metrics for local pollution

The list of available health index scores is found here.  Underneath several of the index scores, there are sub-scores referred to as 'metrics'.  These scores are on the same 0-100, red to green color ramp, but they represent a subset of data that is related to the health index.  When using the health scores in the map, a small down arrow next to the index score name indicates that metrics are available. 

What are the different 'types' of Health Scores, and what do they measure?

A health score may represent:

  • Condition - How much has something changed or been altered?  (Usually as compared to an estimate of a pristine condition)
    • Example:  Hydrology - Perennial Vegetation
    • Score: 0 = no perennial vegetation / 100 = all perennial vegetation
  • Context / Risk - What factors make the health of my landscape vulnerable?  (i.e.; geologic setting, introduced contaminants)
    • Example: Water Qaulity - Localized Pollution Sources Index
    • Score:  0 = highest concentration of risk condition / 100 = risk is not present
  • Response - How is my watershed responding to the conditions and risks? (Usually estimated by measuring the health status of different ecological communities;
    • Example:  Biology - Stream Species Quality Index
    • Score: 0 = No expected species present / 100 = all expected species present

Managing for System Response

When managing natural resource systems, scientists, land managers and private landowners are often asked to address a problem that is actually a 'system response'.  Impaired water quality, flooding, invasive species, poor fishing success - these are all complex responses.

While usually straightforward to measure, a system response is not easy to change.  Watershed conditions and context interact through complex cycles to produce the response, requiring an in-depth understanding of system function to create a new outcome.

There are two ways to manage for a system response.  Like a personal health problem, one choice is to address the symptom (quick, easy); the other is to improve system function (longer, consistent effort).

High Blood Pressure:

  • Option 1:  SYMPTOM MANAGEMENT - Take blood pressure medication
    • Result:  Quickly lowers blood pressure and reduces health risk
    • Tradeoff: Medication use must continue indefinitely, may have side effects.
  • Option 2:  SYSTEM MANAGEMENT - Change lifestyle with better diet and more exercise
    • Result:  Slowly lowers blood pressure, reduces risk over time. 
    • Tradeoff:  Takes longer to see improvement, but better system function improves long-term health and well-being.

Community Flooding

  • Option 1:  SYMPTOM MANAGEMENT - Increase height and length of floodwall through town.  
    • Result:  Immediately protects community members and infrastructure. 
    • Tradeoff:  Floodwall must be maintained indefinitely, constricted stream transfers more water and energy to the rest of the stream system. 
  • Option 2:  SYSTEM MANAGEMENT - Increase natural watershed storage in contributing watershed. 
    • Result:  Less water reaches stream following a storm, reducing flood levels. 
    • Tradeoff:  Takes time to create enough storage to reduce flood flows, but natural storage is self-sustaining and provides many watershed health benefits.