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. 

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

Dissolved Oxygen

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

Natural occurrence

Oxygen is constantly being exchanged between the water surface and the atmosphere, through diffusion and turbulence.

The maximum possible concentration of dissolved oxygen (DO) in water is controlled by atmospheric pressure and water temperature. Oxygen saturation in water is proportional to atmospheric pressure (if one goes up, so does the other, and vice-versa). Dissolved oxygen levels are inversely proportional to water temperature. So, the lower the water temperature, the greater the DO concentration.Higher water temperature relate to lower levels of dissolved oxygen. 

Biologic processes add and remove oxygen from a waterbody. Photosynthesis by aquatic plants and algae produces oxygen, and the decomposition of organic matter by bacteria through aerobic respiration consumes oxygen.

In a nutrient-rich water body, the DO can be quite high in the surface water during the day, due to photosynthesis from algae and aquatic plants, and low at night, due to microorganism respiration.

Because of daily temperature cycles and sunlight, the DO concentration in water tends to undergo diurnal cycles: DO is higher during periods of sunlight when photosynthesis is occurring and lower at night.

In aquatic systems, the physical, chemical, and biological processes interact in complex ways. For example, DO tends to be depleted in deeper waters because of poorer light penetration and subsequently less photosynthesis. Additionally, when dead algae (phytoplankton) sinks, it is decomposed by aerobic bacteria and other microorganisms, which consumes oxygen.

 Additionally, DO can be chemically removed - or bound up - by oxidation of other constituents in the water, such as iron.

How much matters?

DO values less than 5 mg/L are problematic over time 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. A grab sample reading should be compared with Kentucky's instantaneous minimum (acute) criteria, which is 4 mg/L.  Mountain or spring-fed streams designated as cold-water aquatic habitat (i.e., for trout, etc.) require higher DO levels.

Human impacts on concentrations

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. The warmed waters naturally hold less oxygen.

Also, 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. 

Temperature affects the metabolic processes of aquatic organisms, as well as the solubility and toxicity of chemical compounds. Generally, the solubility of solids increases with increasing temperature, while gases tend to be more soluble in cold water. Temperature is also a factor in determining allowable limits for other parameters, such as ammonia.

Natural occurrence

Temperature varies naturally on a daily and seasonal basis. Natural factors affecting water temperatures in streams include direct sunlight and warm water outflows from shallow ponds or reservoirs. Groundwater - which averages between 55° and 60° F in Kentucky - can influence stream temperature. Mixing of shallow groundwater and surface water commonly occurs in the hyporheic zone, the subsurface area below and adjacent to stream channels where many organisms find refuge during drought and extreme temperatures.

How much matters?

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. Temperatures for warmwater streams should not exceed 89° F; coldwater streams should not exceed 68° Fahrenheit.

Higher temperatures can reduce oxygen concentrations and affect growth, reproduction, and metabolic processes in fish and other organisms - sometimes fatally. 

Human impacts

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.

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. Conductivity can naturally vary depending on the location of the waterbody and the underlying bedrock and soils. Because of this natural variation, some regions of the state have higher background levels.

A conductivity measurement can also serve as a general indicator of water contamination. 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. 

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.

Escherichia coli (E. coli) is naturally found in the intestinal tract of all warm-blooded animals and 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, including waste from humans, livestock, wildlife, and pets.  Fecal matter can contain bacteria and 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. 

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

• Excellent: 0-130 MPN/100ml

• Good: 130-240 MPN/100ml

• Fair: > 240 to 2,399 MPN/100 ml

• Poor: > 2,400 MPN/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)