Probabilistic Program

The biological communities living in West Virginia streams are exposed to stressors, including contaminants, sedimentation, nutrient enrichment, and acidity. 

The WVDEP uses benthic macroinvertebrates to assess the biological condition of streams in the state. 

These organisms provide reliable information on water and habitat quality in streams, because of their diversity and wide range of tolerances to pollutants. 

Measures of benthic macroinvertebrate communities are assessed through family-level and genus-level based indices of biotic integrity. 

The IBIs’ metrics compare biological samples to reference conditions. 

The Aquatic Life Criteria Attainment Threshold (ALCAT) uses genus-level data specifically to determine attainment. A technical memorandum describing ALCAT can be found in Appendix B.

*Based on the ALCAT percent of threshold (where scores <100 are not attaining and >= 100 are attaining)* 

Statewide

68.1% of wadeable stream miles are attaining for aquatic life use

30.4% of stream miles are non-attaining

1.5% are Non-Comparable 

Ecoregion

The ecoregion with the highest percentage of streams attaining the Aquatic Life Use was the Ridge and Valley (66/67) at 84.1%, followed by the Central Appalachians (69) at 67.3%, and Western Allegheny Plateau (70) at 60.7%.

Basin

The basin with the most attaining stream miles for aquatic life (78.3%) is Potomac. 

The basin with the lowest number of attaining stream miles (62.0%) is Monongahela. 

A portion of streams in the Potomac Basin (8.4%) are not considered comparable because of natural conditions from karst limestone geology.

pH (S.U.) is a measure of water’s acidity or basicity and is one of the most influential properties of water.

As pH levels fall below 6.0 or rise above 9.0, physiological stress occurs in many aquatic organisms. Lower pH levels (increasing acidity) may heighten the toxicity of ammonia and many metals.

In WV, acid precipitation and acid mine drainage are the most common causes of low pH acidic waters.

High pH waters may be the result of:

• naturally alkaline rocks and soils leaching into streams and may be exacerbated by physical disturbances such as tilling, mining, and construction,

• treatment for acidic streams using alkaline materials, and/or

• high photosynthetic activity, which removes carbon dioxide from water and raises pH.

For attainment, West Virginia §8.24 (requirements governing water quality standards) states that pH should have “no values below 6.0 nor above 9.0. Higher values due to photosynthetic activity may be tolerated.” 

An evaluation of statewide probabilistic data indicates that approximately 95.9% of the stream miles in WV are attaining the pH criterion.

Only 4.1% of the stream miles in the state are non-attaining, with pH values below 6.0.

Ecoregions

The Western Allegheny Plateau had 0.0% of stream miles impacted by pH while the Ridge and Valley only had 2.8%. The Central Appalachians had the most stream miles impacted by pH at 8.3%. It should be noted that the Central Appalachians are where the majority of Acid Deposition in WV has been documented.   

Basins 

On a smaller scale, the basins with the fewest pH impacted stream miles from this dataset are Upper Ohio (0.0%) and Potomac (0.0%).  

The Upper Ohio basin includes streams from Upper Ohio North, Upper Ohio South, Middle Ohio North, Little Kanawha, and Middle Ohio South 8-digit watersheds. The Potomac basin includes streams within the Cacapon, North Branch Potomac, South Branch Potomac, Potomac Direct Drains, and Shenandoah 8-digit HUC watersheds. 

The Monongahela basin has the highest level of low pH impacted waters among basins, with 8.2% of stream miles estimated to be acidic. 

Streams receiving mine drainage may be impaired by low pH and/or elevated concentrations of metals, including iron, aluminum, and manganese. 

Other contaminants such as sulfate may also be present in concentrations above background levels. A sulfate concentration greater than 50 mg/L was used to identify probabilistic sites influenced by mine drainage. 

In WV, approximately 15.6% of the stream miles statewide are influenced by mine drainage. 

Ecoregions

Observed on an ecoregional basis, mine drainage influences a greater proportion of stream miles in the coal-rich Central Appalachians (27.3%) than in the Ridge and Valley (2.5%) or Western Allegheny Plateau (9.2%). 

Basins

Among basins, the Lower Ohio (29.2%) and Lower Kanawha (20.7%) had the highest percentage of streams miles exceeding the 50 mg/L threshold of sulfate. The Potomac Basin had the lowest percentage of stream miles influenced by mine drainage with 3.4%.

Many West Virginia streams contain elevated levels of fecal coliform bacteria. 

Contributors to the problem include:

• leaking or overflowing sewage collection systems, 

• homeowner sewage discharges by straight pipes or failing septic systems, and 

• runoff from urban or residential areas and agricultural lands with livestock. 

Based on statewide probabilistic data, 17.5% of stream miles in WV have fecal coliform bacteria levels that exceed the criterion of 400 colonies/100mL. 

Ecoregions

Percent Stream Miles exceeding the WV criterion for bacteria

Western Allegheny Plateau - 27.2% non-attaining

Central Appalachians - 14.0% non-attaining

Ridge and Valley - 6.3% non-attaining

*The Western Allegheny Plateau tends to have a higher population density and broader agricultural land cover than the two other ecoregions.*

Basins

The basin with the highest percent (88.1%) of attaining stream miles is Upper Kanawha.

The Lower Ohio basin has the fewest percent (67.0%) of attaining stream miles. 

*WVDEP’s probabilistic monitoring is performed at baseflow conditions. Since samples are not collected during storm runoff events, bacteria levels that may increase under these higher flow conditions are not represented in the data.

Nitrogen (N) is a critical constituent of proteins and nucleic acids in all living organisms. 

It is an essential nutrient for growth in aquatic plants and algae. 

Excess nitrogen concentrations in aquatic environments can stimulate excess algal growth. 

Total nitrogen (TN) measures the amount N from all nitrogen forms. These include elemental nitrogen (N2), nitrite (NO2-), nitrate (NO3-), ammonia nitrogen (NH4+), and organic nitrogenous compounds). 

Elevated nitrogen concentrations often result from: 

• fertilizer runoff, 

• animal wastes, 

• wastewater discharges, and/or

• atmospheric deposition.  

West Virginia does not have a criterion for TN to assess attainment in streams. Therefore, for this probabilistic assessment, WVDEP used USEPA’s method for the National Rivers and Streams Assessment (2018-19) to establish benchmarks. The 75th percentile of WVDEP reference samples (<=0.82 mg/l) was used to establish Excellent to Very Good conditions for TN and the 95th percentile (>1.33 mg/L)) to define Marginal to Poor. Total nitrogen concentrations >0.82 mg/L & <=1.33 mg/L were in Good to Fair condition. 

An evaluation of statewide probabilistic data indicates that approximately 85.8% of the stream miles in WV are Excellent to Very Good in terms of TN concentrations, 10.1% are Good to Fair, and only 4.1% are Marginal to Poor.

Ecoregions

The Western Allegheny Plateau had both the highest percentage of stream miles in Excellent to Very Good condition (92.7%) and the lowest percentage of stream miles in Marginal to Poor condition (0%). 

The Central Appalachians and Ridge and Valley had roughly the same percentage of stream miles in Marginal to Poor condition (6.6 and 6.9% respectively). 

However, the Central Appalachians had more stream miles in Excellent to Very Good condition (84.2%) than the Ridge and Valley (75.9%). 

*The disparity in TN between the Western Allegheny Plateau and the Central Appalachians/Ridge and Valley may point to sources of Nitrogen outside of urban and agricultural origins (e.g., Atmospheric Deposition).*

Basins

The basin with the highest percent (92.9%) of stream miles in the Excellent to Very Good category is Upper Ohio, and the basin with the fewest is Potomac with an estimate of 70.4%.   

The Potomac basin had the most streams in Marginal to Poor at 9.4%. 

Phosphorus (P) is a highly reactive, non-metallic element and an essential nutrient for all living organisms.

Phosphate minerals are the most common form of phosphorus.  Small increases in available phosphorus can cause substantial increases in algal growth.  

Like nitrogen, streams enriched with excess phosphorus may exhibit:

• low dissolved oxygen concentrations, 

• overabundances of filamentous algae and diatoms, and 

• frequent aquatic life kills, including fish. 

WVDEP measured total phosphorus (TP) concentrations for this probabilistic survey. Because there is no WV criterion for TP in streams, WVDEP used USEPA’s method for the National Rivers and Streams Assessment (2018-19) to establish benchmarks. The 75th percentile of WVDEP reference samples (<=0.02 mg/L) was used to establish Excellent to Very Good conditions for TP and the 95th percentile (>0.03 mg/L) to define Marginal to Poor. Total phosphorus concentrations >0.02 mg/L & <=0.03 mg/L were considered in Good to Fair condition. 

Based on a statewide scale, an estimated 73.2% of stream miles are Excellent to Very Good in terms of TP levels, and 16.6% are Marginal to Poor.

Ecoregions

Unlike TN, the more densely populated Western Allegheny Plateau had the lowest percentage of stream miles with TP in Excellent to Very Good condition (60.1%) and highest percentage in Marginal to Poor condition (25.9%). 

The Ridge and Valley was the best ecoregion regarding TP (86.7% Excellent to Very Good; 9.0% Marginal to Poor) followed closely by the Central Appalachians (78.7% Excellent to Very Good; 11.9% Marginal to Poor).

Basins

The basin with the highest percent (84.8%) of stream miles in the Excellent to Very Good category is Potomac, and the basin with the fewest is Upper Ohio with an estimate of 59.9%.   

Additionally, the Upper Ohio basin has the most streams miles in Marginal to Poor condition at 23.7%.  The percentage of stream miles in the Marginal to Poor category (20.3%) is also relatively high in the Lower Ohio basin.

The overall habitat RBP score has a max score of 200 points.  For this report, habitat quality is Excellent to Very Good if the Total RBP Score is 200-151, Good to Fair if 150-101, and Marginal to Poor if 100-0.

Based on probabilistic data, 24.2% of stream miles statewide have Excellent to Very Good habitat quality, 67.4% of stream miles have Good to Fair habitat quality, and 8.4% of stream miles have Marginal to Poor habitat quality.

Ecoregions

The ecoregion with the best overall habitat quality is Central Appalachians with an estimate of 38.1% of stream miles rates as Excellent to Good.

The Ridge and Valley ecoregion has the fewest stream miles (4.4%) in Marginal to Poor condition while Western Allegheny Plateau has the highest stream miles in Good to Fair condition (83.9%).

Basins

The basin with the best overall habitat quality is Upper Kanawha with an estimate of 59.4% of stream miles rated as Excellent to Very Good.  

The Lower Ohio basin has the fewest stream miles (1.7%) in Marginal to Poor condition and has the highest percent (87.8%) in the Good to Fair category.  

The Upper Ohio basin had the second highest percentage of stream miles rated Good to Fair (81.6%).  

The Monongahela basin has the most stream miles in Marginal to Poor condition with an estimate of 16.0%.

Excessive sediment in streams may have significant negative effects on instream habitats and the biological communities that use them.  

Interstitial spaces used by aquatic life for cover, feeding, and reproduction are often filled when sedimentation rates are high.  

Two of the most common sediment particles documented in WV streams are

• Sand

• Silt  

Soil erosion is the most common source of sediments and is natural to some degree.

Soil erosion is made worse by human disturbances and activities such as: 

• • • Roads 

    • Construction projects 

    • Logging 

    • Oil/gas extraction

    • Farming

    • Various types of mining  

Sediment deposition was assessed at probabilistic sites using a component parameter of the overall RBP habitat score ranging from 20-0. Sites with scores ranging from 20-16 are considered Excellent to Very Good, 15-11 are Good to Fair, and 10-0 are Marginal to Poor. 

Statewide

Based on statewide probabilistic data, 7.0% of stream miles are in Excellent to Very Good condition in terms of sedimentation, 48.2% are Good to Fair, and 44.9% are Marginal to Poor. 

Ecoregions

The Western Allegheny Plateau had 0% of stream miles in the Excellent to Very Good condition and the highest percentage of stream miles rated Marginal to Poor (66%).

The Ridge and Valley had the highest percentage in Excellent to Very Good condition (18.4%) followed by the Central Appalachians (8%)

Basins

The basin with the best sedimentation scores is Upper Kanawha with an estimate of 19.8% of stream miles rated as Excellent to Very Good, and 34.4% rated as Marginal to Poor.

The Potomac basin has the fewest stream miles (29.0%) in Marginal to Poor condition and has the second highest percent (17.0%) rated Excellent to Very Good. 

The Upper Ohio basin does not have any stream miles rated Excellent to Very Good for sediment deposition and has the most rated as Marginal to Poor with 59.7%. 

The Lower Ohio basin has a relatively high percentage of stream miles in Marginal to Poor condition with an estimate of 52.9%.

One of the most important problems facing West Virginia streams is the relative presence of embedded sediment.

Embeddedness measures the extent to which rocks (gravel, cobble, and boulders) are covered or sunken into the silt, sand, or mud at the bottom of the stream. 

Fish and macroinvertebrates use the surface area of the stream bottom for:

• shelter

• spawning

• egg incubation

Generally, as rocks become embedded, the available surface area is decreased. 

Embeddedness is primarily rated in the erosional areas of a stream where there is fast moving water.

Embeddedness was assessed at probabilistic sites using the component VBHA parameter. The scoring for this parameter ranges from 0-20. Sites with scores ranging from 16-20 are considered Excellent to Very Good, 11-15 are Good to Fair, and 0-10 are Marginal to Poor.

Statewide

Based on probabilistic data, 11.7% of stream miles statewide are in Excellent to Very Good condition, 60.2% are Good to Fair, and 28.1% are Marginal to Poor for embeddedness of sediment. 

Ecoregions

The Ridge and Valley had the highest percentage in Excellent to Very Good condition (27.1%) followed by the Central Appalachians (13.6%).

The Western Allegheny Plateau had both the lowest percentage of stream miles rated as Excellent to Very Good (1.7%) and highest percentage rated as Marginal to Poor (42.0%) for embeddedness. *This is likely because this ecoregion has slower, low-gradient streams, has more erodible soils, and more land-disturbing activities than in other areas.* 

Basins

The basin with the best embeddedness scores is Upper Kanawha with an estimate of 21.4% of stream miles rated as Excellent to Very Good, and only 19.7% rated as Marginal to Poor. 

The Potomac basin has the fewest stream miles (19.3%) in Marginal to Poor condition and has the second highest percent (21.2%) in Excellent to Very Good condition. 

The Upper Ohio basin has only 1.8% stream miles rated Excellent to Very Good. 

The Monongahela basin has the highest percentage of stream miles in Marginal to Poor condition with an estimate of 36.9% followed closely by the Lower Kanawha at 34.1%.

Riparian Zones: 

• Provide shade

• Create a more stable stream bank

• Minimize the amount of sediment, excess nutrients and other pollutants entering the stream

This indicator rates streamside zones on the amount of undisturbed vegetation present.

Riparian vegetation can also help reduce floodwater velocity.  

For streamside riparian zones, the most desirable situation includes:

• Large native trees in the canopy 

• Smaller native trees and shrubs in the understory & 

• Native herbs/grasses with leaf litter for ground cover

Examples of poorly maintained riparian zones are well manicured lawns mowed to the water’s edge and parking lots with no trees or shrubs.

Statewide

Statewide, 32.6% of stream miles have Excellent to Very Good riparian zones and 36.9% have Marginal to Poor riparian zones. 

Ecoregions

In the Ridge and Valley ecoregion, 44.1% of stream miles have Excellent to Very Good riparian Zones and 26.6% have Marginal to Poor riparian zones. 

Central Appalachians had 45.3% of stream miles in Excellent to Very Good and 22.8% of stream miles Marginal to Poor condition.

The Western Allegheny Plateau did not perform as well as the other two ecoregions with only 12.5% of stream miles rated as Excellent to Very Good and 58% rated as Marginal to Poor.

*The Western Allegheny Plateau has a higher population density and lower percentage of publicly owned land than the mountainous Central Appalachian and Ridge and Valley ecoregions. These two factors help explain the differences in Riparian Vegetative Zone Width between the ecoregions.*

Basins

The Upper Kanawha basin has the most intact riparian zones with 58.8% of stream miles Excellent to Very Good and only 14.6% Marginal to Poor. 

The Potomac basin has the second fewest stream miles (27.7%) in Marginal to Poor condition and has the second highest percent (42.7%) in the Excellent to Very Good category.  

The Upper Ohio basin has the least intact riparian zones overall with 12.5% of stream miles Excellent to Very Good and 59.6% Marginal to Poor.

The Aesthetic/Trash Index is a measure of the amount of human refuse or “trash” that is in and around the stream including that could be washed into the stream at high flows.  

Trashy conditions in streams can have negative impacts on recreation, tourism, and the economy. 

When it accumulates in or near a community, it may create health and safety risks for those living there. 

While it is primarily used as a measure of the aesthetic condition of a stream site, trash pollution can cause damage to aquatic habitats by smothering them and by reducing living spaces, for example.  Other trash items have the potential to release pollutants that are toxic to aquatic life.  

Like an RBP habitat parameter, the scoring for this parameter ranges from 20-0, with lower scores indicating more trash present in the stream.  Sites with scores ranging from 20-16 are considered Excellent to Very Good, 15-11 are Good to Fair, and 10-0 are Marginal to Poor. 

Statewide

Based on probabilistic data, 42.8% of stream miles statewide have little to no trash in them and are in Excellent to Very Good condition, 36.3% are Good to Fair, and 20.8% are Marginal to Poor.

Ecoregions

The Ridge and Valley had the highest percentage of stream miles rated Excellent to Very Good (61.9%) and lowest percentage rated Marginal to Poor (6.3%).

The Central Appalachians had the most stream miles rated as Marginal to Poor (25.7%) followed by the Western Allegheny Plateau (22.8%). 

The Western Allegheny Plateau also had the lowest percentage of stream miles in the Excellent to Very Good condition (25.4%).

Basins

The Upper Kanawha basin has the least trashy conditions with 71.0% of stream miles Excellent to Very Good and only 9.6% Marginal to Poor.

The Potomac basin was also relatively clean in terms of trash abundance with 60.2% of stream miles rated Excellent to Very Good and only 7.5% rated Marginal to Poor.

Trash was most abundant in streams of the Lower Ohio basin with 46.3% of stream miles rated Marginal to Poor and only 27.6% Excellent to Very Good.