BIOLOGY - Health Scores

Biology Component Mean Health Score

watershed health scores thumbnail

key for map

Click map to enlarge and explore Watershed Health Assessments.

Component Level Scores

For each of the five components, their health index scores are combined to create a mean (average) overall component health score.

What do the biology index scores show?

The combined four biology indices reveal a pattern of lower scores within the Minnesota and Red River basins. The very low Terrestrial Habitat Quality scores appear to be the primary driver of this trend. The overall range statewide is quite narrow particularly when viewing the mean scores.








Input Data


Calculating the mean


Calculating the minimum


Pattern of results


Interpreting the results



Future enhancements

Biology data inputs

Terrestrial Habitat Quality »

National Land Cover Dataset (NLCD, 2001)
MN County Biological Survey - Biodiversity Significance
Roads (MN DOT, 2010)
National Agricultural Statistic Service (NASS, 2007)

Stream Species Quality »

Indicators of Biotic Integrity Stream Survey Database (PCA, 1996-2006)
MN DNR Statewide Mussel Survey Database (MN DNR, 1989-2010)

Species Richness »

Indicators of Biotic Integrity Stream Survey Database (PCA, 1996-2006)
Statewide  Mussel Survey Database (MN DNR, 1989-2010)
Breeding Bird Survey (BBS, 1995-2008)

At-Risk Species Richness »

Species of Greatest Conservation Need (MN DNR Wildlife Conservation Strategy 2006)
Indicators of Biotic Integrity Stream Survey Database (PCA, 1996-2006)
MN DNR Statewide  Mussel Survey Database (MN DNR, 1989-2010)
Breeding Bird Survey (BBS, 1995-2008)


Mean biology health rankings

Four biology index values (below) are combined into one mean (average) biology score for each watershed. The overall mean score for Biology reveals statewide trends in system health. Although it may mask any extreme values, it illustrates an overall gradient in results by basin and region. The mean can also be used to compare similar watersheds, such as upstream or downstream within the same basin.  View the mean score together with the index scores to discover how different index values influence the overall mean.   


Biology Index Inputs:

Click maps to explore each health index:

Terrestrial Habitat Quality

terrestrial hab quality health scores thumbnail

Stream Species Quality

stream species quality health scores thumbnail

Species Richness

species richness health scores thumbnail

At-Risk Species Richness

at risk species richness health scores thumbnail

Minimum biology health rankings

The minimum is the lowest of the four biology index scores calculated for each watershed. Like the lowest grade on a report card, it may indicate an area in need of focus and effort to improve overall watershed health. It may help identify the most impacted or limiting aspect of the system.

The map on the left shows the lowest biology index value in each watershed.  The map on the right identifies which index scored the lowest in each watershed. 

Minimum Biology Scores

Click maps to enlarge and explore Watershed Health Assessments:

Lowest Biology Index Value

Biology Minimum health scores thumbnail

Lowest Scoring Biology Index

Pattern of results

Both the minimum and mean biology scores generally decrease from north to south and from east to west across Minnesota, although the range of values is quite narrow.  The pattern by index is more variable, with the largest range in results in the Terrestrial Habitat Quality index.  Very low Terrestrial Habitat Quality scores are predominant throughout the Red River, Minnesota and Lower Mississippi major river basins.  Stream Species and Species Richness scores are slightly higher in these same basins.  At-Risk Species Richness scores are higher in the St. Croix basin and the southeast blufflands.  Northern Minnesota scores are only slightly higher than the other regions of Minnesota, in part due to a low richness of At-Risk Species in those watersheds.    


Interpreting results

In many parts of Minnesota, the lack of quality terrestrial habitat is extensive.  This lack of habitat may be limiting species distribution and richness as reflected in the other indices. 

The Species Richness scores include both terrestrial and aquatic species and show a trend toward higher richness in east central Minnesota.  The higher scores reflect the increase in richness related to unique niche habitats found in the St. Croix Basin; as well as the breeding bird survey pattern of increased species counts through central Minnesota. 

Conversely, the Minnesota River Basin received very low At-Risk Species Richness scores,  following the pattern of very low Terrestrial Habitat Quality scores. 

The highest Terrestrial Habitat Quality scores in north central Minnesota also received the highest Stream Species Quality and Species Richness scores. 


Future Enhancements

Currently, this component does not include data on the health status of Minnesota's many lakes.  An aquatic habitat quality index is planned and this may incorporate aquatic lake IBI (index of biotic integrity) data as well as other habitat parameters. This work will be coordinated with a planned update to the terrestrial habitat quality model.  The habitat model is scheduled to be refined and recalculated with newer land cover data.  The refinement will include reducing the negative impact of lakes causing "fragmentation" of terrestrial habitat in modeling results.