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Nonpoint Source Water Pollution

Nonpoint Source > Watershed Assessment > Impaired Waters - Integrated Report > Section 303(d) List of Impaired Waters > Impairments (and other constituents) Considered in Assessing Indiana Waters Impairments (and other constituents) Considered in Assessing Indiana Waters

Table of Contents

Impaired Biotic Communities (IBC)

Biological communities – the fish and aquatic invertebrates, such as insects, in stream – are indicators of the cumulative effects of activities that affect water quality conditions over time. An IBC listing on Indiana’s 303(d) list, means IDEM’s monitoring data shows one or both of the aquatic communities are not as healthy as they should be. IBC is not a source of impairment but a symptom of other sources.

Dissolved Oxygen (DO)

The amount of DO in surface waters is important. Aquatic organisms depend on DO in the water to breathe. A DO listing on Indiana’s 303(d) list means IDEM’s monitoring data shows the concentrations of DO is lower than needed to support the aquatic communities. Also, low DO or results showing supersaturation of DO are considered a symptom of other sources of problems in the waterbody that are currently unknown.

pH

The pH level is a measure of the acidity in the water. pH levels that are too low or too high can have harmful affects on aquatic organisms. Most aquatic life needs a minimum pH of 6 to survive. A pH listing on Indiana’s 303(d) list means IDEM’s monitoring data shows the concentrations of pH outside the appropriate range for pH in water.

Metals Impairments (applicable to all metals)

Heavy metals, such as, Zinc, Nickel, Lead and Aluminum, Iron, Magnesium and Copper, are concerns in surface waters due to the harmful affects they have on aquatic life. When found in water, metals can interfere with the bodily functions of fish and aquatic insects. A metals listing on Indiana’s 303(d) list means IDEM’s monitoring data shows the concentrations of metals is in exceedances of the WQS.

Nutrients

Nutrients such as phosphorus and nitrogen are a concern for surface waters because excessive amounts can result in large “blooms” of algae. This can cause negative effects on aquatic communities. A nutrient listing on Indiana’s 303(d) list means IDEM’s monitoring data shows the concentrations of nutrients high enough to adversely affect the aquatic ecosystem and affect the aquatic communities. Unlike other chemical impairments, nutrients are considered a symptom of other sources to the problem in the waterbody that are currently unknown. The normal parameters of concern for nutrients are nitrogen, phosphorus, dissolved oxygen, pH and professional observations of algae.

Algae

Algae are a normal component of a healthy aquatic ecosystem. Excessive algae can lead to an imbalanced aquatic ecosystem which can create a nuisance or potential impact on the aquatic community. The algae impairments on Indiana’s 303(d) list are historical impairments related to nutrient issues. Prior to 2006, where the amount of algae in a stream or lake was sufficient to create a nuisance or potentially cause a fish kill, a stream was assessed as impaired.

Taste & Odor

The taste and odor impairments on Indiana’s 303(d) list are historical impairments related to public drinking water supplies. Prior to 2006, where source water required additional treatment, due to algae, IDEM assessed their source waters as impaired. Taste and odor issues are commonly the result of excessive algae.

Bacteria/E. coli

E. coli is a bacteria present in the feces of warm-blooded animals. E. coli in surface waters can lead to illness in humans. IDEM monitors E. coli in surface waters to determine whether the waterbody supports swimming and other recreational uses. An E. coli listing on Indiana’s 303(d) list means IDEM’s monitoring data shows the concentrations of E. coli is in exceedances of the WQS.

Inorganic Impairments: These are all related to aquatic life use

Sulfate

Sulfate in surface water is a concern because in excess, it can react with dissolved metals in the water to form other more toxic chemicals and can change the pH of the water, making it more acidic. A sulfate listing on Indiana’s 303(d) list means IDEM’s monitoring data shows the concentrations of sulfate is in exceedances of the WQS.

Chloride

High salinity (chloride) may interfere with the growth of aquatic vegetation which can affect the aquatic ecosystem. A chloride listing on Indiana’s 303(d) list means IDEM’s monitoring data shows the concentrations of chlorides is in exceedances of the WQS.

Nitrogen

Nitrogen promotes plant growth. Excessive nitrogen can cause an excess of algae blooms which can affect the amount of oxygen in the water and decrease light penetration. While nitrogen is not used to determine assessments of water bodies, its relationship to other designated impairments, such as algae and nutrients, has resulted in using nitrogen studies in some TMDL developments.

Phosphorus

Phosphorus promotes plant growth. Excessive phosphorus can cause and excess of algae blooms which affecting the amount of oxygen in water and decrease light penetration. While phosphorus is not used to determine assessments of water bodies, its relationship to other designated impairments, such as algae and nutrients, has resulted in using phosphorus studies in some TMDL developments.

Ammonia

Ammonia is extremely toxic and even relatively low levels pose a threat to aquatic biota. An ammonia listing on Indiana’s 303(d) list means IDEM’s monitoring data shows the concentrations of ammonia is in exceedances of the WQS.

Cyanide

Fish and aquatic invertebrates are particularly sensitive to cyanide exposure. High concentrations of cyanide reduce swimming performance, inhibit reproduction and causes death. A cyanide listing on Indiana’s 303(d) list means IDEM’s monitoring data shows the concentrations of cyanide is in exceedances of the WQS.

Organic Impairments

Pesticides

Repeated exposure to certain pesticides can result in negative physical affects on fish and invertebrates. Pesticides can also reduce the availability of plants and insects, food sources for fish and other aquatic life. A pesticide listing on Indiana’s 303(d) list means IDEM’s monitoring data shows the concentrations of pesticides is in exceedances of the WQS.

Total Dissolved Solids (TDS)

TDS is a measure of the amount of material dissolved in water. The TDS impairments on Indiana’s 303(d) list are historical impairments related to other factors already being measured, such as the inorganic and organic impairments, listed above.

Sediment/Siltation

Siltation and sediments cause waterbodies to become imbedded with mud that can smother eggs and larvae, destroy macroinvertebrate habitat, and food sources for bottom feeding aquatic life. A sediment/siltation listing on Indiana’s 303(d) list means IDEM’s monitoring data shows the concentrations of sediment/siltation is at levels that impact aquatic communities.

Total Suspended Solids (TSS)

High concentrations of suspended solids reduce light passing through the water slowing photosynthesis. Reduced photosynthesis causes less dissolved oxygen. Suspended sediment clog’s fish gills, reduce growth, decrease resistance to disease, and prevent egg and larval development. While TSS is not used to determine assessments of water bodies, its relationship to other designated impairments, such as impaired biotic communities (IBC) and nutrients has resulted in using TSS measurements in some TMDL developments.

Oil & Grease

Oil and grease are used as an impairment type due to its adverse affect on water quality, aquatic life, human health, and recreational opportunities. As an impairment type it is now only a legacy code no longer used. This has been replaced with polycyclic aromatic hydrocarbon (PAH) and other priority organics.

Fish Impairments

Mercury

Mercury, primarily methyl mercury, is quickly accumulated by aquatic biota. Mercury accumulation by organisms has resulted in adverse effects ranging from sub-lethal effects to deaths. Mercury listings on Indiana’s 303(d) list means IDEM’s monitoring data shows the concentrations of mercury in fish tissue exceeds the level for healthy aquatic communities and human consumption.

Polychlorinated biphenyls (PCBs)

Aquatic organisms in the natural environment obtain their PCB burden from both water and food which has been contaminated via water and air deposition. The guidelines for PCBs in fish and sediment are used for the assessment of existing water quality. PCB listings on Indiana’s 303(d) list means IDEM’s monitoring data shows the concentrations of PCB in fish tissue exceeds the level for healthy aquatic communities and human consumption.

Dioxins

Dioxins mainly derive from human activities, but can to a lower extent be generated naturally by forest fires or volcanic activity. Dioxins have no use as such and are formed unintentionally by industrial processes and incomplete combustion. Water quality is directly affected through water and air deposition of these sources of dioxins. Dioxin listings on Indiana’s 303(d) list means IDEM’s monitoring data shows the concentrations of dioxin in fish tissue exceeds the level for healthy aquatic communities and human consumption.