The EPA notes that the water quality of the streams of the Eastern Highlands was of the greatest concern. Not only were a mere Overall, The Macroinvertebrate Index of Biotic Condition is a statistical measure that provides a total score based on six characteristics of the macroinvertebrates found in a particular water sample. This total score is one indicator of water quality. Researchers determine which species of macroinvertebrates are present in a particular water sample, the proportion of each, the level of diversity of species within the sample high-quality water has a high level of diversity , and the feeding habits, habitats, and pollution tolerance of the species present.
Each of these characteristics is an indicator of water quality, and together they provide a snapshot of the macroinvertebrate "naturalness" in the portion of the stream tested. The researchers then use this total score, factor in the stream length represented by the study site, and use the data from all the study sites to compile the Macroinvertebrate Index ratings for the stream miles of a region and for the nation. Nationally, The Eastern Highlands had the most stream length in poor condition: The West had the most stream length in good condition: Four chemical stressors were assessed for the Wadeable Streams Assessment : phosphorus, nitrogen, salinity, and acidification.
The levels of these stressors in the samples were compared with data from a set of "least disturbed" reference sites in each region to develop regional thresholds for all indicators. Phosphorus and nitrogen are plant nutrients. When phosphorus and nitrogen enter bodies of water — usually as runoff from fertilized land, leaking septic systems, or sewage discharges — they promote aquatic plant and algal growth.
Plant and algal growth can become excessive, a process called eutrophication. This excessive growth can result in waters clogged with plants and algae, which can look unsightly, slow water flow, and interfere with swimming and fishing. Mats of algae can grow on the surface of the water, blocking light to plants beneath. When these plants die, bacteria degrade them, using oxygen in the process and diminishing the concentration of oxygen in the water available for aquatic macroinvertebrates and fish.
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With lowered dissolved oxygen in the water, many fish and invertebrates die, worsening the situation. Phosphorus is a common component of fertilizers and was routinely found in laundry detergents until the industry removed phosphates from its products in However, phosphates are still found in dishwashing detergents and in some cleaners. These phosphates wash down the drain during or after use and enter either septic systems or sewage treatment plants.
From there, the phosphates can end up in bodies of water as they leach into the ground from septic systems or are discharged into streams with treated wastewater from sewage treatment plants. Agricultural runoff containing phosphate fertilizers is also a common source of added phosphates in bodies of water.
The EPA summarizes in the Wadeable Streams Assessment by stating that "high phosphorus concentrations in streams may be associated with poor agricultural practices, urban runoff, or point-source discharges e. Nationally, nearly one-third However, nearly half Regionally, the highest percentage of stream miles with high levels of phosphorus was in the Eastern Highlands, where The Plains and Lowlands had Nitrogen is another plant nutrient, as noted previously.
It finds it way into streams primarily from agricultural runoff it is found in fertilizer , wastewater and animal waste it is a waste product from the digestion of protein , and atmospheric deposition it is released into the air when fossil fuels, such as gasoline and coal, are burned.
Nitrogen is particularly important as a contributor to the rapid, excessive growth of algae along coastal waters and in estuaries, where freshwater meets the saltwater of the ocean. The statistics are similar to those for phosphorus. However, close to half Regionally, the highest percentage of stream miles with high levels of nitrogen was in the Eastern Highlands, where The Plains and Lowlands had about one-quarter Excessive salinity in freshwater streams generally occurs because water is lost from the stream, not because excessive salts enter the stream.
This happens when the evaporation rate of stream water is high. Already high salinity from evaporation can be made higher by repeated water withdrawals for irrigation or other purposes. The West had only 2. Stream acidification means that the water has become more acidic than is natural. The pH scale shows levels of acidity. This scale is numbered from zero to fourteen, with a pH value of seven considered neutral. Values higher than seven are considered more alkaline or basic; values that are lower than seven are considered acidic. Pure, distilled water has a pH level of seven. The pH scale is a logarithmic measure.
This means that every pH drop of one is a tenfold increase in acid content. Therefore, a decrease from pH six to pH five is a tenfold increase in acidity; a drop from pH six to pH four is a hundredfold increase in acidity; and a drop from pH six to pH three is a thousandfold increase.
It is not neutral because it is not pure water; it accumulates naturally occurring sulfur oxides and nitrogen oxides as it passes through the atmosphere. In comparison, acid rain or acid deposition has a pH of about 4.
The introduction of large volumes of acid deposition can over time increase the acidity of a body of water by as much as a hundredfold. One of the main components of acid deposition is sulfur dioxide from the burning of fossil fuels, mainly from auto exhaust and coal-burning power plants. As sulfur dioxide reaches the atmosphere, it becomes sulfuric acid when it joins with hydrogen atoms in the air.
Nitric oxide and nitric dioxide are the other major components of acid deposition. Like sulfur dioxide, these nitrogen oxides are produced from the burning of fossil fuels. They rise into the atmosphere and oxidize in clouds to form nitric acid. Gases and particulate matter are carried into the atmosphere, where they mix with moisture and other pollutants to form dry aerosols, particles, and gases and wet fog, hail, rain, sleet, snow, dew acid deposition.
Wet deposition returns to the earth as precipitation, which enters the water body directly, percolates through the soil, or becomes runoff to nearby water bodies. Dry deposition builds up over time on all dry surfaces and is transported to water bodies in runoff during periods of precipitation or falls directly onto a water surface. These sources include acid deposition 0. Although these numbers appear relatively small, they reflect a significant impact in certain parts of the United States, particularly in the Eastern Highlands region, where 3.
Freshwater streams are the physical habitats natural homes for a variety of plants and animals. The physical characteristics of a stream can be changed by human activities, and those changes can be stressors for the organisms that live there. EPA researchers assessed these physical characteristics of wadeable streams: streambed sediments, in-stream fish habitat, riparian vegetative cover, and riparian disturbance.
Water and sediments drain into streams as the result of a number of human-related activities, including agriculture, road building, construction, and the grazing of farm animals. Drainage of water and sediments into a stream can affect its size and shape. In addition, the size of the sediment particles can affect the streambed.
If sediment particles are large, the stream may not be able to move them downstream, so they eventually accumulate in the streambed, changing habitats. If the particles are small but excessive, the stream may not be able to move them as well. Fine sediments that are left in the streambed can begin filling in the habitat spaces between stones and boulders on the stream bottom.
Suspended fine sediments can block sunlight to aquatic plants and abrade the gills of fish. All these occurrences can negatively affect macroinvertebrates and fish. Streams and rivers that have diverse and complex habitats support a diversity of fish and macroinvertebrates.
Such habitats include undercut banks with exposed tree roots, brush and large pieces of wood within the stream, and boulders within the stream and at the stream bank. Cover from overhanging vegetation also affects stream habitats.
When humans use streams, they often change these complex habitats to simpler ones, which often results in a reduction in the diversity of the organisms living there. About one-fourth The West was next, with Nonetheless, the West had the greatest number of stream miles with instream habitats rated good: The word riparian means the banks of a body of water, such as a river or stream. In the Wadeable Streams Assessment , riparian vegetative cover refers to the amount and type of vegetation growing on or next to stream banks; it is an indicator of the health of a stream.
Complex, multilayered riparian vegetation helps maintain the health of the stream by reducing runoff from the surrounding land, preventing stream bank erosion, supplying shade, and providing food and habitats in the form of leaf litter and large wood. As with in-stream habitats, riparian coverage is often changed, or simplified, by humans.
EPA researchers assessed the ground layer, woody shrubs, and canopy trees of the riparian cover of streams. The Eastern Highlands followed with As mentioned earlier, human activities can change or disturb the riparian vegetative cover. The closer potentially disturbing human activities take place to the stream bank, the more likely they are to cause riparian disturbance. To determine riparian human disturbance, EPA researchers tallied eleven forms of human activities and disturbances along sections of streams and weighted them according to how close they were to the streams.
Nearly half The EPA notes in the Wadeable Streams Assessment that "one of the striking findings [was] the widespread distribution of intermediate levels of riparian disturbance," both nationally and regionally. Furthermore, the EPA states, "It is worth noting that for the nation and the three regions, the amount of stream length with good riparian vegetative cover was significantly greater than the amount of stream length with low levels of human disturbance in the riparian zone.
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This finding warrants additional investigation, but suggests that land managers and property owners are protecting and maintaining healthy riparian vegetation buffers, even along streams where disturbance from roads, agriculture, and grazing is widespread. The bar graph on the left shows what percentage of stream length nationally each stressor affects and what its relationship is to the other stressors. Each stressor is ranked according to the proportion of stream length that was in poor condition nationally.
Excessive nitrogen levels affected the greatest percentage of stream miles at Phosphorus, the other plant nutrient assessed, was a close second, affecting Excess salinity and acidification affected the least percentage of stream miles, 2. Search for books, journals or webpages All Pages Books Journals. View on ScienceDirect. Editor-in-Chiefs: J. Imprint: Academic Press.
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