Water Quality Data Explained

Field Chemistry

Dissolved Oxygen - Oxygen is introduced into water from the surrounding atmospheric air through aeration (rapid movement of the water) and as a product of photosynthesis by aquatic vegetation.Dissolved oxygen is a requirement for the metabolism and survival of aquatic, aerobic organisms and also influences inorganic chemical reactions within the waterbody.The amount of water that can dissolve in pure water is inversely proportional to temperature of the water.The warmer the water, the less dissolved oxygen.A dissolved oxygen value less than 5 mg/L is problematic for aquatic organisms, causing increased susceptibility to environmental stresses, reduced growth rates, mortality and an alteration in the distribution of aquatic life.

Temperature - In addition to having its own toxic effect, water temperature affects the solubility and the toxicity of many other water quality parameters.Generally, the solubility of solids increases with increasing temperature, while gases tend to be more soluble in cold water.An important physical relationship exists between the amount of dissolved oxygen in a body of water and its temperature.The warmer the water, the less dissolved oxygen.Colder water can maintain greater dissolved oxygen concentrations.

 pH - The pH is a numerical measure of the acidity or alkalinity of water.The pH scale ranges from 1 (acidic) to 14 (alkaline).A pH value less than 6 signifies acidic conditions in which toxic heavy metals are more soluble, and therefore more available for uptake by aquatic life.At pH values greater than 9, toxic ammonia concentrations increase.

TurbidityTurbidity is a measure of water clarity and how much the material suspended in the water decreases the passage of light through the water.Suspended materials include soil particles (clay, silt and sand), algae, plankton, microbes, and other substances.Sources of turbidity include soil erosion, waste discharge, urban runoff, eroding streambanks, large numbers of bottom feeders which stir up bottom sediments and excessive algal growth (USEPA, www.epa.gov/owow/monitoring/volunteer/stream/vms55.html).

Higher turbidity increases water temperatures, because suspended particles absorb more heat.This, in turn, reduces the concentration of dissolved oxygen because warm water holds less dissolved oxygen than cold water.Higher turbidity also reduces the amount of light penetrating the water, which reduces photosynthesis and the production of oxygen.Suspended materials can clog fish gills, reducing resistance to disease in fish, lowering growth rates, and affecting egg and larval development.As the particles settle, they can blanket the stream bottom, especially in slower waters, and smother fish eggs and benthic macroinvertebrates.

Stream Flow - Flow, also called discharge, refers to the volume of water flowing through a point in the stream per second. Water flowing in streams constitutes land runoff, either over impermeable surfaces, through soils, or from groundwater. Following a rain event, there is often a quick increase in flow due to rainwater reaching the stream, followed by a relatively long decline back to baseflow. The rapid increase in flow can result from rainwater quickly running off of impermeable surfaces or through soils. Alternatively, the rapid increase could be due to rainwater pushing out water that had been stored in wetlands or groundwater. Baseflow is the amount of water that would drain absent any rain inputs, and is usually from groundwater.

Conductivity - Conductivity is a measurement of the ability of an aqueous solution to carry an electrical current.Conductivity measurements are used to determine levels of total inorganic dissolved solid ions, such as nutrients, metals, or other compounds.Indirect effects of high conductivity levels are primarily the elimination of plants needed for food or habitat and the decline of sensitive aquatic species, such as mayflies and fish.

The EPA's newly established conductivity criterion for streams in Central Appalachia is 500 micromohs/cm.In central Appalachia, the conductivity of headwater streams is naturally between 100 micromhos/cm and 200 micromhos/cm  This is important because the plants, insects and animals in local streams have adapted to living in this level of conductivity.Recent studies conducted by the EPA show that when the conductivity in central Appalachian streams rises to about 300 micromhos/cm, the plants, insects and animals begin to be affected.  When the conductivity of these streams goes above 500 micromhos/cm, the plants, insects and animals are drastically affected.  And when the conductivity measures above 1,000 micromhos/cm, everything in the stream is effectively dead.  [NOTE: KDOW sampling has shown that some pollutant-tolerant aquatic life is present at conductivity levels greater than 1,000.micromhos/cm]In other regions of the country the natural conductivity may be higher or lower than in central Appalachia, and the plants, insects and animals there will have adapted over thousands of years to live within those natural conductivity levels.


Triazine - Triazine (or Atrazine) is a selective triazine herbicide used to control broadleaf and grassy weeds in corn and other crops, and in conifer reforestation plantings.It is also used as a nonselective herbicide on non-cropped industrial lands and on fallow lands.Atrazine is moderately soluble in water.Atrazine is highly persistent in soil.Chemical hydrolysis followed by microbial breakdown accounts for most of its degradation in soil.Although hydrolysis is rapid in acidic or basic soil environments, it is slower at neutral pHs.

2,4-Dichlorophenoxyacetic acid (2,4-D) - 2,4-D is a common systemic herbicide used in the control of broadleaf weeds. It is the most widely used herbicide in the world, and the third most commonly used in North America.According to the US EPA's website, the short-term health effects of exposure to high levels of 2,4-D in drinking water can include nervous system damage.Long-term exposure to 2,4-D can potentially cause damage to the nervous system, kidney and liver.


A number of pathogenic (disease causing) viruses, bacteria, and protozoans can enter a water body via fecal contamination.Human illness can result from drinking water or swimming in water that contains pathogens.Eating shellfish harvested from such waters may also result in human illness.

Unfortunately, direct testing for pathogens is impractical.Pathogens are rarely present in large numbers, and many are difficult to cultivate in the lab.Instead, microbiologists look for ¡°indicator¡± species ¨C so called because their presence indicates that fecal contamination may have occurred.The indicators most commonly used today include: total coliforms, fecal coliforms, Escherichia coli, fecal streptococci, and enterococci.Each of these bacteria are normally prevalent in the intestines and feces of warm-blooded animals, including humans.The indicator bacteria themselves are not usually pathogenic.All but E. coli are composed of a number of species of bacteria that share common characteristics such as shape, habitat, or behavior.E. coli is a single species in the fecal coliform group.It should be pointed out that when a water sample is determined to contain E. coli, that does not necessarily mean that the dangerous strain (i.e. E. coil O157:H7) is actually present, it is probably not, however this would indicate recent fecal contamination.

E. coli The bacteria, E. coli, is commonly found in the intestines of healthy humans and animals and produces the K and B¨C complex vitamins that are then absorbed for nutritional benefit.The presence of E. coli in water indicates fecal contamination and the potential for waterborne disease.EPA recommends E. coli as the best indicator of health risk from water contact in recreational waters.Kentucky has transitioned from a fecal coliform standard to an E. coli standard.[Recently, Akasapu and Ormsbee (2011) developed a mathematical approximation between fecal coliform values (FC) and E. Coli values for samples in the Kentucky River Basin which can be used to relate past fecal coliform values to ¡°equivalent¡± E. coli values.The relationship is:E.coli= 1.435*FC0.8093 ]

The state criteria for E. coli are based on the designated use of the particular stream and may be summarized as follows: Primary Contact Recreation (swimming from May 1 thru Oct 31): E. coli shall not exceed 130 colonies per 100 ml as a monthly geometric mean based on not less than 5 samples per month; nor exceed 240 colonies per 100 ml in 20 percent or more of all samples taken during the month [Note: As a result of the sampling frequency requirement with the first criteria, the state of Kentucky uses the 240 colonies per 100-ml criteria for classifying streams in the 305(b) report].

Laboratory Chemistry

Alkalinity - Alkalinity refers to the degree to which the water sample is basic, or has a pH greater than 7, and affects the capability of water to neutralize acid.In most natural water bodies in Kentucky the buffering system is carbonate-bicarbonate.Alkalinity is important for fish and aquatic life because it protects or buffers against rapid pH changes.Higher alkalinity levels in surface waters will buffer acid rain and other acid wastes and prevent pH changes that are harmful to aquatic life.Kentucky's water quality criteria state that for protection of aquatic life, the buffering capacity should be at least 20 mg/L.If alkalinity is naturally low, (less than 20 mg/L) there can be no greater than a 25% reduction in alkalinity.

Chlorides - Chlorides are salts resulting from the combination of the gas chlorine with a metal.Fish and aquatic communities cannot survive in waters with high levels of chlorides.The state of Kentucky requires that chloride levels be less than 250 mg/L in domestic water supplies. Criteria for protection of aquatic life require levels of less than 600 mg/L for chronic (long-term) exposure and 1200 mg/L for short-term exposure.

Total Suspended Solids - One of the biggest sources of water pollution in Kentucky is suspended solids.Suspended solids include inorganic particles (silts, clays, etc.) and organic particles (algae, zooplankton, bacteria, and detritus) that are carried along by water as it runs off the land. The inorganic portion is usually considerably higher than the organic. Both contribute to turbidity, or cloudiness of the water.High values of TSS cause multiple environmental impacts, including clogging fish gills, reducing light penetration, and siltation of stream bottoms and associated habitats.Indirectly, the suspended solids affect other parameters such as temperature and dissolved oxygen.Suspended solids also interfere with effective drinking water treatment. High sediment loads interfere with coagulation, filtration, and disinfection, and more chlorine is required to effectively disinfect turbid water.

There are no quantitative criteria for TSS.The Kentucky Water Quality Standards for aquatic life state that suspended solids "shall not be changed to the extent that the indigenous aquatic community is adversely affected" and "the addition of settleable solids that may adversely alter the stream bottom is prohibited."


Oxygen demanding materials and plant nutrients are among the most common substances discharged to the environment by man's activities, through wastewater facilities and by agricultural, residential, and stormwater runoff.The most important plant nutrients, in terms of water quality, are phosphorus and nitrogen.In general, increasing nutrient concentrations increase the potential for accelerated growth of aquatic plants, including algae.Nuisance plant growth can create imbalances in the aquatic community, as well as cause aesthetic and access issues.High densities of phytoplankton (algae) can cause wide fluctuations in pH and dissolved oxygen.

Nutrient delivery, particularly during the months of April through June, has been identified as one of the primary factors controlling the size of the hypoxic zone that forms during the summer in the northern Gulf of Mexico. The Gulf hypoxic zone is an area where oxygen levels drop too low to support most life in bottom and near-bottom waters.A Mississippi River/Gulf of Mexico Watershed Nutrient Task Force was created in 1997 to address the Massachusetts-size dead zone that is threatening the Gulf's fisheries. In 2011, the Task Force identified Kentucky and Indiana as two of the top six among 31 states contributing excess nitrogen and phosphorus to the Gulf from sources such as sewage treatment plants, farms and power plant emissions.It recommended that Kentucky, and other states contributing the most to the problem, enact new nutrient reduction strategies by 2013.

Total Phosphorus - Total phosphorus is commonly measured to determine phosphorus concentrations in surface waters.This measurement ncludes all of the various forms of phosphorus (organic, inorganic, dissolved, and particulate) present in a sample. Phosphorus is one of the key elements necessary for growth of plants and animals. Phosphates are made up of phosphorus and exist in three forms: orthophosphate, metaphosphate (or polyphosphate) and organically bound phosphate. Each compound contains phosphorous in a different chemical formula. Ortho forms are produced by natural processes and are found in sewage.Poly forms are used for treating boiler waters and in detergents. In water, they change into the orthoform.Organic phosphates are important in nature.Their occurrence may result from the breakdown of organic pesticides that contain phosphates.They may exist in solution, as particles, loose fragments, or in the bodies of aquatic organisms.

In addition to man-made sources, some phosphorus loadings may occur naturally from the watershed soils and underlying geology.Due to background levels of total phosphorus in the Kentucky River Basin as high as 0.25 mg/L, those sites with average total phosphorus concentrations of 0.3 mg/L can be noted as potentially problematic.The informal total phosphorus standard of 0.3 mg/L has been adopted by the KRWW Scientific Advisory Committee as an appropriate level of concern for water quality sampling conducted in the Kentucky River Basin.This value has also been recommended for use by the Kentucky Division of Water.

 Nitrogen - Nitrogen is routinely analyzed at most Kentucky ambient sampling sites in the forms of ammonia and ammonium (NH3/NH4), total Kjeldahl nitrogen (TKN), and nitrite and nitrate (NO2/NO3).Ammonia and ammonium are readily used by plants.TKN is a measure of organic nitrogen and ammonia in a sample.Nitrate is the product of aerobic transformation of ammonia, and is the most common form used by aquatic plants.Nitrite is usually not present in significant amounts.Nitrates can react directly with hemoglobin in the blood of humans and other warm-blooded animals to produce methemoglobin, which destroys the ability of red blood cells to transport oxygen. This condition is especially serious in babies under three months of age and causes a condition known as methemoglobinemia, or "blue baby" disease.

The state drinking water supply standard for nitrate-nitrogen, which is a measurement of the nitrogen potion of the nitrate (NO3) molecule, is 10 mg/L.In order to monitor nutrient effects on aquatic life, KRWW is using a proposed standard of 3 mg/L, because this nitrate level has been demonstrated to produce nutrient-rich conditions supporting algal blooms, along with other aquatic habitat threats.

Sulfur - Sulfur is another essential plant nutrient. Aquatic organisms utilize sulfur, and reduced concentrations have a detrimental effect on algal growth. The most common form of sulfur in well-oxygenated waters is sulfate. Sulfates (SO4--) can be naturally occurring or the result of municipal or industrial discharges. When naturally occurring, they are often the result of the breakdown of leaves that fall into a stream, of water passing through rock or soil containing gypsum and other common minerals, or of atmospheric deposition. Point sources include sewage treatment plants and industrial discharges such as tanneries, pulp mills, and textile mills. Runoff from coal mining operations and fertilized agricultural lands also contributes sulfates to water bodies.

A sulfur cycle exists, which includes atmospheric sulfur dioxide (SO2), sulfate ions (SO22-) and sulfides (S-). Sulfides, especially hydrogen sulfide (H2S), are quite soluble in water and are toxic to both humans and fish. They are produced under conditions where there is a lack of oxygen (anaerobic). Because of their foul "rotten egg" smell they are avoided by both fish and humans. Sulfides formed as a result of acid mine runoff from coal or other mineral extraction and from industrial sources may be oxidized to form sulfates, which are less toxic.

When sulfate is less than 0.5 mg/L, algal growth will not occur. On the other hand, sulfate salts can be major contaminants in natural waters.The state water quality standard for sulfate in drinking water supplies is 250 mg/L.


Antimony is a USEPA priority pollutant that can be toxic to plants and animals. In addition to the natural occurrence of antimony in bedrock and streambed sediments in the Knobs Region of the Kentucky River Basin, antimony salts are used in the fireworks, rubber, textile, ceramic, glass, and paint industries.The proposed maximum contaminant level (MCL) in finished drinking water for antimony ranges from 5 to 10 micrograms per liter.

Arsenic occurs naturally in rocks and soil, water, air and plants and animals.It can be further released into the environment through natural activities, such as volcanic action, erosion of rocks, and forest fires, or through human actions.Approximately 90 percent of industrial arsenic in the U.S. is currently used as a wood preservative, but arsenic is also used in paints, dyes, metals, drugs, soaps and semi-conductors.High arsenic levels can also come from certain fertilizers and animal feeding operations.Industry practices, such as copper smelting, mining and coal burning also contribute to arsenic in our environment.Arsenic levels tend to be higher in ground water than in surface water (lakes and rivers).Levels also tend to be higher in the western United States.

Barium is a yellowish-white alkaline earth metal. It combines with water to produce barium hydroxide and is found in nature as barites (BaSO4), witherite (BaCO3), and other ores. Barium and its salts are often used in metallurgical industries for special alloys, in paints, and concrete.Because of the insolubility of most of its compounds, it is not considered to be an ecological threat.

Beryllium is an uncommon alkaline-earth element that is recognized as a USEPA priority pollutant and potential carcinogen.The USEPA has proposed a MCL of 1.0 micrograms per liter for beryllium, and Kentucky has adopted the USEPA lowest-observed effect levels (LOEL) for protection of aquatic life, which are 130 micrograms/liter (1.3 mg/L) and 5.3 micrograms/liter (0.053 mg/L) for acute and chronic toxicity, respectively. In addition, Kentucky water-quality criteria establish a beryllium criterion of 0.117 micrograms per liter for the protection of human health from the consumption of fish tissue. The criterion is based upon an acceptable risk level of no more than one additional cancer case in a population of 1 million people.

Cadmium is a non-essential element and it diminishes plant growth. It is considered a potential carcinogen. It also has been shown to cause toxic effects to the kidneys, bone defects, high blood pressure, and reproductive effects.Cadmium is widely distributed in the environment at low concentrations. It can be found in fairly high concentrations in sewage sludge. Primary industrial uses for cadmium are plating, battery manufacture, pigments, and plastics.

 Chromium is ubiquitous in the environment, occurring naturally in the air, water, rocks and soil. It is used in stainless steel, electroplating of chrome, dyes, leather tanning and wood preservatives. It occurs in several forms, or oxidation states. The two most common are chromium VI and chromium III. The form depends on pH. Natural sources of water contain very low concentrations of chromium. It is a micronutrient (or essential trace element). High doses of chromium VI have been associated with birth defects and cancer; however, chromium III is not associated with these effects. Plants and animals do not bioaccumulate chromium; therefore, the potential impact of high chromium levels in the environment is acute toxicity to plants and animals. In animals and humans this toxicity may be expressed as skin lesions or rashes and kidney and liver damage.

Copper is a USEPA priority pollutant that is a micronutrient for the growth of plants and animals, but even small concentrations of copper in surface water can be toxic to aquatic life.Copper sulfate is frequently used to control nuisance growths of algae in water supply reservoirs.The toxicity of copper is a function of the total hardness of the water, because copper ions are complexed by anions that contribute to water hardness.Although detectable concentrations of copper in water are not known to have an adverse effect on humans, the MCL for copper has been established at 1,000 micrograms/liter, which corresponds with the taste threshold concentration for this element.

Iron is the fourth most abundant element, by weight, in the earth's crust. Natural waters contain variable amounts of iron depending on the geological area and other chemical components of the waterway. Iron in groundwater is normally present in the ferrous or bivalent form (Fe2+), which is soluble. It is easily oxidized to ferric iron (Fe3+) or insoluble iron upon exposure to air. This precipitate is orange-colored and often turns streams orange.Iron is a trace element required by both plants and animals. It is a vital part of the oxygen transport mechanism in the blood (hemoglobin) of all vertebrate and some invertebrate animals.Ferrous Fe2+ and ferric Fe3+ irons are the primary forms of concern in the aquatic environment.Other forms may be in either organic or inorganic wastewater streams. The ferrous form can persist in water void of dissolved oxygen and usually originates from groundwater or mines that are pumped or drained. Iron in domestic water supply systems stains laundry and porcelain. It appears to be more of a nuisance than a potential health hazard. Taste thresholds of iron in water are 0.1 mg/L for ferrous iron and 0.2 mg/L for ferric iron, giving a bitter taste or an astringent taste. Water to be used in industrial processes should contain less than 0.2 mg/L iron. Black or brown swamp waters may contain iron concentrations of several mg/L in the presence or absence of dissolved oxygen, but this iron form has little effect on aquatic life.

Leadis primarily found in nature as the mineral galena (lead sulfide). It also occurs as carbonate, as sulfate and in several other forms. The solubility of these minerals and also of lead oxides and other inorganic salts is low. Major modern day uses of lead are for batteries, pigments, and other metal products. In the past, lead was used as an additive in gasoline and became dispersed throughout the environment in the air, soils, and waters as a result of automobile exhaust emissions. For years, this was the primary source of lead in the environment. However, since the replacement of leaded gasoline with unleaded gasoline in the mid-1980's, lead from that source has virtually disappeared. Mining, smelting, and other industrial emissions and combustion sources and solid waste incinerators are now the primary sources of lead. Another source of lead is paint chips and dust from buildings built before 1978 and from bridges and other metal structures.

Nickel is a USEPA priority pollutant that can adversely affect humans and aquatic organisms.Nickel is an important industrial metal that is used extensively in stainless steel. Substantial amounts of nickel can be contributed to the environment by waste disposal and atmospheric emissions. Nickel ions are toxic, particularly to plant life, and can exhibit synergism when present with other metallic ions.

Selenium is a nonmetallic trace element that is listed as a primary pollutant by the USEPA.Selenium is an essential micronutrient for plants and animals, but can be toxic in excessive amounts. Selenium is a relatively rare element, and concentrations of selenium in natural waters seldom exceed 1.0 microgram/liter. Sources of selenium in the Kentucky River Basin include sedimentary rocks and fly ash from coal-fired power plants that operate in Kentucky.

Silver is a USEPA priority pollutant that is extensively used for photography and various industrial and commercial purposes. Although average concentrations of silver in natural waters are small (0.3 micrograms/liter), elevated silver concentrations can be acutely or chronically toxic to aquatic organisms, and sublethal amounts can bioaccumulate in fish and invertebrate organisms.

Thallium is a USEPA priority pollutant that can be toxic to humans and aquatic life. Thallium salts are used as poison for rats and other rodents, as well as in dyes, pigments in fireworks, and optical glass .

Zinc is found naturally in many rock-forming minerals. Because of its use in the vulcanization of rubber, it is generally found at higher levels near highways. It also may be present in industrial discharges. It is used to galvanize steel, and is found in batteries, plastics, wood preservatives, antiseptics, and in rat and mouse poison (zinc phosphide).Zinc is an essential element in the diet. It is not considered very toxic to humans or other organisms.