Potential Impacts
High alkalinity will protect sensitive aquatic organisms from changes in pH. The acid-neutralizing or buffering capacity of water is essential for aquatic life to thrive.

Potential Causes
Naturally occurring alkalinity is determined by the rock strata in which water flows through. Sedimentary rocks, which are rich in carbonate, bicarbonate, and hydroxide compounds, are indicative of a high alkalinity. Conversely, granitic rocks and sandstones are associated with a low alkalinity.

Potential Impacts
Elevated levels of ammonia can injure or kill aquatic life, such as fish and invertebrates. In fish, even low concentrations of ammonia can damage sensitive tissues such as gills, can deplete natural resistances to bacterial infections, and can hinder reproductive capacities and growth.

Potential Causes
Ammonia occurs naturally as a by-product of protein metabolism and decomposition. Ammonia can also enter a water body from runoff of fertilizers, livestock waste, and from discharges of untreated sewage and industrial wastewater.

Potential Impacts
Although small amounts of chlorides are essential to proper cell function in plants and animals, large concentrations of chlorides can damage aquatic life physiology and hinder reproductive fertility and growth.

Potential Causes
Chlorides occur naturally from the weathering and erosion of sedimentary rocks. Agricultural runoff, industrial wastewater, petroleum industrial activities, salt water intrusions, and effluent from WWTFs are sources of chlorides.

Potential Impacts
Chlorophyll-a, as a photosynthetic pigment found in green plants, is an indicator of the presence of algae in the water. It is used to monitor the trophic status of lakes or the primary productivity of ecosystems.

Potential Causes
Elevated levels of nutrients could result in high concentrations of algal biomass.

Potential Impacts
Dioxin is a family of polychlorinated chemicals. It is carcinogenic and is detrimental to animal and human health.

Potential Causes
Dioxin is present in the waste from the paper bleaching process and from the combustion of chlorinated compounds.

Potential Impacts
The most important component for the survival of aquatic life is oxygen. DO is essentially the amount of oxygen available in water. Low dissolved oxygen will suffocate aquatic species, and a high amount of dissolved oxygen will reduce water odors.

Potential Causes
Elevated levels of organic nutrients can cause an overabundance of bacteria and algae, which depletes oxygen from water. Increases in water temperature will also lower the capacity for water to hold oxygen.

Potential Impacts
Escherichia coli and Enterococci are bacterial indicator species for the presence of fecal matter, pathogenic bacteria, and viruses.

Potential Causes
Malfunctioning or failing on-site sewage facilities (OSSF), untreated domestic sewage, improper disposal of grease, and runoff from agricultural and livestock activities can cause an overabundance of bacteria and other pathogens.

Potential Impacts
Flow conditions affect water quality. Aquatic species are adapted to specific in-stream flow patterns. Low flow events, associated with hot summer months, can severely alter a stream habitat. High flow events associated with heavy rain or melting snow can also disrupt an aquatic habitat.

Potential Causes
Drought or heavy rain events can disrupt normal flow patterns. Impediments, such as fallen trees, beaver dams, or man-made dams can disrupt or alter in-stream flow.

Potential Impacts
Mercury is a highly toxic metallic element. When it is entered into an aquatic habitat, it can form methylmercury. Methylmercury accumulates in the fatty tissue of aquatic organisms. Humans who consume fish and other aquatic organisms with high concentrations of methylmercury risk developing acute neural toxicity and birth defects.

Potential Causes
Mercury occurs from natural and man-made sources. The most common is atmospheric deposition from burning of fossil fuels and other industrial activities.

Potential Impacts
An abundance of nutrients can increase plant and algal growth. Bacteria use oxygen in the decomposition of plant matter, which can reduce dissolved oxygen. Nitrites are an intermediate form of Nitrogen that can cause “brown blood disease” in fish by preventing the transfer of oxygen by hemoglobin. Nitrites can also adversely affect human health, especially children under the age of three.

Potential Causes
Nutrient sources are usually found in runoff from fertilizers and livestock facilities. They are also present in the effluent of WWTFs.

Potential Impacts
Polychlorinated biphenyls are acutely toxic, and can disrupt endocrine and neural processes in aquatic life and humans.

Potential Causes
PCBs are found in dielectric fluids used in transformers, capacitors, and coolants.

Potential Impacts
Aquatic organisms have evolved to live in a specific range of pH. Biological and chemical processes can be altered or affected if the pH drops or rises over certain thresholds. Fish species cannot survive if the pH drops below 4 or rises above 12.

Potential Causes
Runoff from mining operations and discharges of industrial wastewater can alter the pH of a water body.

Potential Impacts
Most phosphorus compounds found in water are phosphates. Orthophosphate is consumed by aquatic plants and organisms and is considered the limiting factor for aquatic plant growth. High or excessive levels of orthophosphate results in higher yield in growth. Excessive plant growth can cause eutrophication, (the natural aging progression of a water body) which will decrease dissolved oxygen levels.

Potential Causes
Phosphates occur naturally from the decomposition of organisms. Sources also include the weathering of rock material and runoff from fertilizers.

Potential Impacts
Salinity is the measurement of conductive ions in the water. High levels of sodium sulfate and magnesium sulfate produce a laxative effect in drinking water. High levels of total dissolved solids can cause an unpleasant taste in potable water.

Potential Causes
Weathering or erosion of rocks, salt mining, and salt water intrusions are sources of increased salinity.

Potential Impacts
Secchi transparency is used to calculate the depth at which natural light can penetrate the water column. It also used as a measurement of eutrophication, the natural aging progression of a water body.

Potential Causes
An abundance of algae and plants or excessive levels of TSS will decrease the ability for light to transmit through the water column.

Potential Impacts
In the absence of oxygen and with a pH below 8, bacteria will reduce sulfate ions to sulfide ions. Sulfide ions will cause serious and unpleasant odor problems. Sulfates in sediment can also alter soil composition and hinder or prevent growth of native plants.

Potential Causes
Sulfate is derived from rocks and soils containing gypsum, iron sulfides, and organic compounds. Sulfur containing fossil fuels, heavy industrial activities, and some fertilizers are also potential sources for sulfates.

Potential Impacts
The types of aquatic life that can survive in a waterbody are dependent upon the water temperature. Water temperature can affect levels of dissolved oxygen. Water with a high temperature has less capacity to hold oxygen. As the water temperature drops, cold-blooded animals such as fish can become more susceptible to pathogenic stress or shock, which can lead to infections or death.

Potential Causes
Releases of water from reservoirs can contribute to drops in temperature. Temperatures will increase with the removal of flora from riparian areas or from the release of heated water from industrial activities.

Potential Impacts
Elevated amounts of total dissolved solids can be corrosive to sewer and plumbing fixtures. Also, high TDS will affect the aesthetic quality of water.

Potential Causes
Elevated amounts of TDS occur naturally from salt deposits, salt water intrusions, and sedimentary rock high in carbonate. Salt mining, petroleum exploration, potable water treatments, wastewater discharges, and chemical, storm water, fertilizer runoff can increase the amounts of total dissolved solids.

Potential Impacts
Total hardness is the measurement of ions such as calcium and magnesium. A high hardness concentration will prevent the toxic effects of heavy metal pollutants. An elevated hardness measurement is indicative of a high alkalinity.

Potential Causes
The weathering or erosion of sedimentary rocks will contribute to high total hardness in a water body.

Potential Impacts
Total Organic Carbon is the measurement of the amount of organic carbon in water. It can be used as an indicator of eutrophication, as well as in potable water treatment.

Potential Causes
TOC is released in the decomposition of organisms. It is also present in herbicides, pesticides, fertilizers, and detergents.

Potential Impacts
An increase in the amount of total suspended solids will decrease the ability for light to penetrate through the water column. This can decrease the productivity of aquatic plants. As excessive amounts of TSS settle and become sediment, benthic habitats can be altered or destroyed.

Potential Causes
High erosion events, usually coinciding with the removal of riparian floral species and severe flow events will create excess levels of TSS. Unsound agricultural practices can also contribute to soil erosion into waterways.

Potential Impacts
Volatile Suspended Solids are the inorganic compounds found within total suspended solids measurements. They can be used as an indicator for the amount of organic suspended solids found in a water body.

Potential Causes
Industrial wastewater can contribute to increased volatile suspended solids.