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V.W.I.N. Parameters and Ranges for Stream Quality Classifications

pH - is a measure of the acidity of water (the concentration of hydrogen ions in a solution).
Neutral = 7, acidic < 7, alkaline, (basic) > 7. The ambient water quality standard is between
6.0 and 9.0. Natural pH in area streams should be in the range of 6.5 - 7.2. Values below 6.5
may indicate the effects of acid rain or other acidic inputs, and values above 7.5 may be
indicative of an industrial discharge.
  • Grade A = never less than 6.0
  • Grade B = below 6.0 in less than 10% of samples, never below 5.0
  • Grade C = never less than 5.0
  • Grade D = at lease one sample was less than 5.0
Alkalinity (Alk) - measures the acid neutralizing capacity of a stream to acidic inputs (i.e., acid rain). Waters with high alkalinity are well buffered against acidic input, such as from acid rain, decomposing organic matter and industrial effluent. There is no legal standard for alkalinity. Western North Carolina streams tend to have low alkalinity because of generally thin soils and because the underlying granitic bedrock does not contain many acid neutralizing compounds such as calcium carbonate.
  • Grade A = median greater than 30 mg/L (indicates little vulnerability to acidic inputs)
  • Grade B = median 20-30 mg/L (indicates moderate vulnerability to acidic inputs
  • Grade C = median less than 20 mg/L (considered to be vulnerable to acidic inputs)
  • Grade D = median less than 15 ppm (very vulnerable to acidic inputs)
Turbidity (Turb) - measures the visual clarity of a water sample and indicates the presence of fine suspended particulate matter. Streams draining areas where the soil has been disturbed have higher turbidity values, especially after rainfall. Turbidity is an important parameter for assessing the viability
of a stream for trout propagation. Trout eggs can withstand only small amounts of silt before hatching success is greatly reduced. Fish dependant on sight for locating food are also greatly disadvantaged
when water clarity declines. This is why the standard for trout designated streams is 10 NTU while the standard to protect other aquatic life is 50 NTU.
  • Grade A = median less than 5 NTU and exceeded the standard for trout waters 10 in less than 10% of samples, but never exceeded 50 NTU
  • Grade B = median less than 7.5 NTU and never exceeded the 50 NTU standard
  • Grade C = median less than 10 NTU and exceeded 50 NTU in less than 10% of samples
  • Grade D = median greater than 10 NTU or exceeded 50 NTU in more than 10% of samples
Total Suspended Solids (TSS) - is a measure of the concentration (i.e., weight) of particulate matter suspended in the water column. There is not legal standard for TSS. Like turbidity, streams
draining areas where the soil has been disturbed have higher TSS values, especially after rainfall.
  • Grade A = median less than 5 mg/L and maximum less than 100 mg/L, land not measurably disturbed by human activities
  • Grade B = median less than 7.5 mg/L and exceeded 100 mg/L in less than 10% of samples,
    low to moderate land disturbance
  • Grade C = median less than 10 mg/L and exceeded 100 mg/L in less than 10% of samples, moderate to high land disturbance
  • Grade D = median greater than 10 mg/L or maximum exceeded 100 mg/L in more than 10% of samples, high level of land disturbance
Conductivity and metals

Conductivity (Cond) - is a measure of the ability of water to conduct an electrical current. The concentration of dissolved solids and salts determines conductivity. Pure water has no ions and
therefore will not conduct electricity. Dissolved solids and salts could come from soils or from
industrial pollution, wastewater discharge and urban runoff, including those found in rainfall.
  • Grade A = median less than 30 uhmos/cm, never exceeded 100 umhos/cm
  • Grade B = median less than 50 umhos/cm, exceeded 100 umhos/cm in less than 10% of samples
  • Grade C = median greater than 50 umhos/cm, exceeded 100 umhos/cm in less than 10% of samples
  • Grade D = exceeded 100 umhos/cm in more than 10% of samples
Total Copper (Cu) - In most areas, ambient levels are below 1 ppb. Copper is typically found in
brake linings and in fuel emissions.
  • Grade A = never exceeded water quality standard of 7 ppb
  • Grade B = exceeded 7 ppb in less than 10% of samples
  • Grade C = exceeded 7 ppb in 10 to 20% of samples
  • Grade D = exceeded 7 ppb in more than 20% of samples
Total Lead (Pb) - Normal ambient levels are usually below 1 ppb. Lead can be found in
brake linings, industrial wastewater, and in roadside soils leftover from when leaded gasoline was still sold.
  • Grade A = never exceeded water quality standard of 10 ppb
  • Grade B = exceeded 10 ppb in less than 10% of samples
  • Grade C = exceeded 10 ppb in 10 to 20% of samples
  • Grade D = exceeded 10 ppb in more than 20% of samples
Total Zinc (Zn) - Normal ambient levels are usually 5 ppb. Zinc is a major metal component of tire rubber,
brake linings, and galvanized crash barriers.
  • Grade A = median less than 5 ppb, never exceeded water quality standard of 50 ppb
  • Grade B = median less than 10 ppb, exceeded 50 ppb in less than 10% of samples
  • Grade C = median less than 10 ppb, exceeded 50 ppb in 10-20% of samples
  • Grade D = median greater than 10 ppb or concentration exceeded 50 ppb in more than 20% of samples
Nutrients

Total Phosphorus (P) - Phosphorus is an essential nutrient for aquatic plants and algae. It is usually
the limiting nutrient for plant growth because of limited availability. Excessive phosphorus inputs can
lead to excessive algae and plant growth, which can damage water intake pipes and choke out other aquatic life. Sources of phosphorus include soil, disturbed land, wastewater treatment plants, failing
septic systems, runoff from fertilized crops and lawns and livestock waste storage areas. VWIN results only report phosphorus concentrations in the form of orthophosphate (see below). To isolate
phosphorus from the measurement of orthophosphate, divide the orthophosphate concentration by 3.07.
  • Grade A = median not above 0.10 mg/L
  • Grade B = median greater than 0.10 mg/L but less than 0.20 mg/L
  • Grade C = median greater than 0.20 mg/L but less than 0.30 mg/L
  • Grade D = median greater than 0.30 mg/L
Orthophosphate (Ortho P) - is a measure of the dissolved phosphorus immediately available to plants or algae. There is not legal standard but levels should generally be below 0.05 mg/L to prevent
excessive growths of plants and algae downstream.
  • Grade A = median less than ambient level of 0.05 mg/L
  • Grade B = median between 0.05 mg/L but less than 0.10 mg/L
  • Grade C = median greater than 0.10 mg/L but less than 0.20 mg/L
  • Grade D = median greater than 0.20 mg/L
Ammonia Nitrogen (NH3-N) - This nutrient is found in the remains of decaying plant and animal
waste. Levels above the normal ambient level of 0.10 mg/L can be toxic to fish. Sources include agricultural runoff, livestock farming, septic drainage and sewage treatment plant discharges.
  • Grade A = never exceeded 0.50 mg/L
  • Grade B = never exceeded the proposed ambient standard for trout waters in the summer of 1 mg/L
  • Grade C = exceeded 1 mg/L in less than 10% of samples, but never exceeded 2 mg/L
  • Grade D = exceeded 1 mg/L in more than 10% of samples, or at least one sample had a concentration greater than the proposed ambient standard for
    trout waters in the winter of 2 mg/L
Nitrate Nitrogen (NO3-N) - Like phosphorus, this nutrient can lead to excessive algae and plant
growth when concentrations are too high.Sources include septic drainage and fertilizer runoff
from agricultural land and domestic lawns.
  • Grade A = median does not exceed 0.3 mg/L, no sample exceeded 1 mg/L
  • Grade B = less than 10% of samples exceeded 1 mg/L, none exceeded 5 mg/L
  • Grade C = no samples exceeded 5 mg/L
  • Grade D = at least one sample exceeded 5 mg/L
Glossary:
  • ambient = estimate of the naturally occurring concentration of a substance
  • mg/L = milligram per liter
  • NTU = nephelometric turbidity units
  • ppb = parts per billion, equivalent to 1 ug/L (microgram per liter)
  • umhos/cm = micromhos per centimeter

 
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