What? The pH measurement indicates how acidic or basic a solution is and ranges from 0 (very acidic) to 14 (very basic), with 7 being neutral. 

Acceptable Range? Kentucky’s water quality criteria require the pH to be within the range of 6.0 and 9.0 SU to protect aquatic life. 

Why Important?  When the water’s pH is above this range (more basic) or below this range (more acidic), organisms may move away, stop reproducing, or die. Water with a low pH also allows toxic compounds to become more available in the water, possibly harming aquatic life.

Effects on pH?

The acidity or alkalinity of the surrounding soil and geological formations can directly influence the pH of the streams flowing through it.  

Higher pH - Kentucky's limestone bedrock is formed from calcium carbonate, which raises the pH of water in streams flowing through it.  Photosynthesis of aquatic plants and algae can also naturally raise the pH of water.  Wastewater that contains detergents and soap-based products are basic and can increase pH levels.

Lower pH - Other biological processes, such as decay of organic matter in and around the stream, can lower pH levels. Precipitation (especially acid rain) is another contributor to decreased pH levels.  Mining operations can produce acid runoff and groundwater seepage that can lower pH levels.  

What? Aquatic life needs oxygen to survive just like creatures living on the land need oxygen.  While oxygen atoms are present in water molecules, most aquatic life needs dissolved oxygen (DO) gas to live. Oxygen is constantly being exchanged between the water surface and the atmosphere, through diffusion and turbulence. 

Acceptable Range? A DO reading should be greater than Kentucky's instantaneous acute minimum criteria of 4 mg/L.  Mountain or spring-fed streams designated as cold-water aquatic habitat (i.e., for trout, etc.) require higher DO levels.  A longer term average of dissolved oxygen concentrations should be above 5 mg/L.

Why Important? Sustained DO values less than 5 mg/L are problematic for aquatic organisms, resulting in increased susceptibility to environmental stresses, reduced growth rates, mortality, and an alteration in the distribution of aquatic life. Levels that remain below 1-2 mg/L for a few hours can result in a severe fish kill.

Effects on dissolved oxygen?   Faster moving water incorporates more oxygen from the atmosphere than stagnant or slow-moving water. Lower dissolved oxygen values are expected in low gradient streams and springs and spring-fed streams with reduced exposure to atmospheric oxygen.

Lower oxygen levels are also caused by warming water temperatures.  Water temperature and dissolved oxygen are inversely proportional, so cooler water holds more oxygen than warmer water. Water temperature increases when shade trees are removed from streambanks, warmed urban runoff waters enter a stream, or power plants release water used to cool their equipment. These warmed waters naturally hold less oxygen.

Oxygen levels can also be depleted by decaying organic matter, including algae. As nutrient (phosphorus and nitrogen) levels increase from human activities, algal growth increases.  As the algal blooms die off and sink, they are decomposed by aerobic bacteria, which consumes oxygen from the water.

What?  The water temperature should be measured in degrees Celsius at a depth of a few inches below the surface. The thermometer should be placed in flowing water if possible.

Why important?  Water temperature is an important factor in determining water quality and conditions enabling healthy aquatic life.  It directly affects the metabolic processes of aquatic organisms, just as air temperature can impact human health.  When waters are too cold or too warm, species can struggle to survive.  Higher temperatures can reduce oxygen concentrations and affect growth, reproduction, and metabolic processes in fish and other organisms - sometimes fatally. 

Temperature also relates to the solubility or toxicity of chemical compounds in the water. Generally, solubility of solids increases with increasing temperature, while gasses tend to be more soluble in colder water.  This is why higher dissolved oxygen levels are found in cooler waters, and lower dissolved oxygen is found in warmer water.

Acceptable Range?  Activities that change water temperatures beyond natural ranges should be avoided, and are prohibited under Clean Water Act rules. Appropriate temperatures are dependent on the type of stream and where it is located. Lowland streams are often categorized as "warmwater" systems, and are different from mountain or spring-fed "coldwater" streams that support organisms with lower temperature and higher oxygen requirements. Kentucky’s water quality standards for temperature relate to the seasons, with an upper limit of 31.7°C (89°F) for “warmwater streams;” “coldwater streams” should not exceed 68° Fahrenheit. 

Effects on temperature?  Removal of shading riparian (streamside) vegetation and releases of excessively warm water from industrial treatment facilities, wastewater and power plants, parking lots, roofs, and other areas can affect surface water temperatures. Stormwater infiltration, cooling ponds, and riparian vegetation (e.g., shade trees, shrubs, native grasses) can help to mitigate these effects.

What? Conductivity is a measure of the capacity of the water to carry an electrical current through dissolved ions or salts in the water. Salts dissolve into positive and negative ions that conduct currents based on their concentration levels.

Acceptable Range?  Higher conductivity levels (from 500 to 1,000, depending on geographical location) cause stress on aquatic organisms and can impact water supplies for drinking water and industrial use.

Why Important? A conductivity measurement can serve as a general indicator of water contamination and is useful as an early indicator of change in the waterway. Most waterways maintain a fairly constant conductivity level that can be used as a baseline to compare against future measurements.  Aquatic organisms in the stream adapt to this prevailing conductivity level and are impacted when it changes significantly.

Effects on conductivity? Conductivity levels are dependent on a stream’s location and underlying bedrock and soils.  Changes can be caused by flooding, evaporation, or human-caused pollution sources. 

Inorganic substances or minerals conduct electrical current. Negative ions such as bicarbonate, carbonate, chloride, and sulfate and positive ions such as calcium, magnesium, sodium, and potassium are typically the most common dissolved ions. So, as salinity (dissolved salt content) increases, conductivity also increases. In contrast, organic compounds (e.g., oil, plant matter) do not conduct electrical current as much and therefore have low conductivity in water. 

A sudden increase or decrease in conductivity can indicate a pollution impact. For example, agricultural runoff or sewage leaks can cause increases in conductivity due to an influx of chloride, phosphate, or nitrate ions. Runoff of road salts or brine solution can cause extreme increases in conductivity that can have major impacts on waterways.  For a more detailed information about conductivity, please visit the Fondriest Environmental Learning Center’s webpage.

What? Escherichia coli (E. coli) is a type of bacteria that is naturally found in the intestinal tract of people and all warm-blooded animals. It is also commonly found in human and animal feces.

Acceptable Range? Water samples are collected and analyzed for E. coli concentrations to make sure the water is safe for public recreation uses, such as wading, swimming, and boating. Concentrations are measured as colony-forming units (CFUs) or most probable number (MPN) per 100 mL.  Criteria are based on the likelihood of concentration levels to result in illness.  

To interpret your results, Watershed Watch uses the following assessment benchmarks:

• Excellent: 0-130 CFU/100ml

• Good: 130-240 CFU/100ml

• Fair: > 240 to 2,399 CFU/100 ml

• Poor: > 2,400 CFU/100 ml

Kentucky's Water Quality Standards apply to more frequent sampling than is conducted by Watershed Watch.

• < 130 CFU/100 ml as a geometric mean based on no less than five samples taken during a 30-day period OR

• < 240 CFU/100 ml in 20% or more of all samples taken during a 30-day period

NOTE: CFU refers to “colony forming units”, whereas MPN refers to “most probable number”. The difference is that CFU/100ml is the actual count, and MPN/100ml is a statistical probability of the number of organisms (American Public Health 2012) 

Why Important? E. coli does not represent a direct human health threat when found in natural streams and waterways.  However, it is measured as an indicator of potential accompanying threats from fecal contamination from humans, livestock, wildlife and pets.  Animal waste can contain bacteria and viruses or pathogens that may cause waterborne diseases or infections.  Therefore, high E. coli concentrations indicate the greater likelihood that human contact with the water could cause health issues. 

E. coli contributions?

High bacteria levels can be caused by human sewage entering waterways through leaks in municipal sewer systems and lateral lines to homes. These issues are more likely to be apparent when monitoring produces high E. coli levels during low rainfall events and runoff sources are not contributors. High E. coli levels that are observed after rain events may be caused by septic system failures when wastewater is not adequately captured and treated onsite.

Other potential sources of E. coli include livestock pastures and feedlots, pet waste, waterfowl, and wildlife.