AMBIENT SAMPLING PROGRAM
FALL CREEK AMBIENT
In January of 1997, MCHD started an ambient sampling project for Fall Creek.
This project consisted of 9 sites sampled 5 times per month, with geometric means calculated for each site’s E. coli data. The purpose of the project was to find non-CSO (Combined Sewer Outfall) influences of E. coli to Fall Creek.
In addition to the routine stream sampling, approximately 100 storm water outfalls were sampled during rain events. Also, inspections and investigations of these storm water outfalls were conducted during dry weather (no rainfall for at least 72 hours) to determine any sources of contamination.
In 1999, the sampling points were adjusted to coincide with the City’s CSO projects to help determine their overall impact to water quality, as well as to maintain data for historical comparison and continue working on non-CSO influences.
Joint projects were also conducted with the City of Indianapolis Office of Environmental Services and the Indiana Department of Environmental Management in 2002, sampling Mud Creek, Lawrence Creek and Devon Creek, which are tributaries of Fall Creek. This purpose of this project concerned TMDL analysis.
Presently, six sites on Fall Creek are sampled 5 times per month, with geometric means calculated for each site’s E. coli data.
Analysis includes – E. coli, Temperature, pH, Conductivity, Total Dissolved Solids, and Dissolved Oxygen.
State of Indiana standards for E. coli:
“..shall not exceed 125 per 100 ml as a geometric mean based on not less than 5 samples equally spaced over a 30 day period nor exceed 235 per 100 ml in any 1 sample in a 30 day period.”
PLEASANT RUN / BEAN CREEK AMBIENT
Ambient sampling projects began in August 1997 (upper Pleasant Run) and December 1997 (lower Pleasant Run and Bean Creek). The projects consisted of 21 sites sampled 5 times per month with geometric means calculated for each site’s E. coli data. The purpose of the project was to find non-CSO (Combined Sewer Outfall) influences of E. coli to Pleasant Run and Bean Creek. We have conducted surveys of the entire stream and its tributaries, on foot, in addition to doing site-specific sampling to determine sources affecting water quality. We have discovered such influences as dog kennels and chicken coops on the stream banks, horses with unrestricted access to the creek, as well as failing septic system discharges and illegal gray water discharges. Work is ongoing to correct these issues through education and enforcement activities.
In 1999, sampling points were modified to focus more on those tributaries found to have a negative influence to the streams. There are presently three sites on Bean Creek and six sites on Pleasant Run sampled 5 times per month, with geometric means calculated for each site’s E. coli data.
Analysis includes – E. coli, Water Temperature, pH, Conductivity, Total Dissolved Solids, and Dissolved Oxygen.
State of Indiana standards for E. coli:
“..shall not exceed 125 per 100 ml as a geometric mean based on not less than 5 samples equally spaced over a 30 day period nor exceed 235 per 100 ml in any 1 sample in a 30 day period.”
POGUES RUN AMBIENT
Ambient sampling of Pogues Run began in February of 1999. The project consists of 6 sites sampled 5 times per month with geometric means calculated for each site’s E. coli data. MCHD has also conducted surveys of the entire stream and its tributaries, on foot, in addition to doing site-specific sampling to determine sources affecting water quality. This project has also allowed watershed groups to assess the impact of the City’s flood control / CSO (Combined Sewer Outfall) abatement projects, by providing data before and after construction. Specifically, sampling points have been established both upstream and downstream of the engineered wetlands/flood control facility at Emerson Avenue.
Analysis includes – E. coli, Water Temperature, pH, Conductivity, Total Dissolved Solids, and Dissolved Oxygen.
State of Indiana standards for E. coli:
“..shall not exceed 125 per 100 ml as a geometric mean based on not less than 5 samples equally spaced over a 30 day period nor exceed 235 per 100 ml in any 1 sample in a 30 day period.”
EAGLE CREEK AMBIENT
In 2003, Public Access sampling was discontinued and an annual ambient sampling program developed for Eagle Creek. Eight sampling locations were originally sampled. The locations were adjusted in 2004 eliminating three and adding one. These locations monitor the stream from the point it enters Marion County to approximately its confluence with White River.
Analysis includes – E. coli, Water Temperature, pH, Conductivity, Total Dissolved Solids, and Dissolved Oxygen.
State of Indiana standards for E. coli:
“..shall not exceed 125 per 100 ml as a geometric mean based on not less than 5 samples equally spaced over a 30 day period nor exceed 235 per 100 ml in any 1 sample in a 30 day period.”
STATE DITCH/DOLLAR HIDE CREEK AMBIENT
In 2003, Public Access sampling was discontinued and an annual ambient sampling program developed for State Ditch and Dollar Hide Creek. In 2005, sampling of Dollar Hide Creek was discontinued. Sites on Seerley Creek and Mars Ditch, tributaries of State Ditch, have been added.
Analysis includes – E. coli, Water Temperature, pH, Conductivity, Total Dissolved Solids, and Dissolved Oxygen.
State of Indiana standards for E. coli:
“..shall not exceed 125 per 100 ml as a geometric mean based on not less than 5 samples equally spaced over a 30 day period nor exceed 235 per 100 ml in any 1 sample in a 30 day period.”
Temperature
The rates of biological and chemical processes depend on temperature. Aquatic organisms from microbes to fish are dependent on certain temperature ranges for their optimal health. Optimal temperatures for fish depend on the species: some survive best in colder water, whereas others prefer warmer water. Benthic macroinvertebrates are also sensitive to temperature and will move in the stream to find their optimal temperature. If temperatures are outside this optimal range for a prolonged period of time, organisms are stressed and can die. Temperature is measured in de-grees Fahrenheit (F) or degrees Celsius (C).
For fish, there are two kinds of limiting temperatures the maximum temperature for short exposures and a weekly average temperature that varies according to the time of year and the life cycle stage of the fish species. Reproductive stages (spawning and embryo development) are the most sensitive stages.
Temperature affects the oxygen content of the water (oxygen levels become lower as temperature increases); the rate of photosynthesis by aquatic plants; the metabolic rates of aquatic organisms; and the sensitivity of organisms to toxic wastes, parasites, and diseases.
Causes of temperature change include weather, removal of shading, streambank vegetation, impoundments (a body of water confined by a barrier, such as a dam), discharge of cooling water, urban storm water, and groundwater inflows to the stream.
pH
pH is a term used to indicate the alkalinity or acidity of a substance as ranked on a scale from 1.0 to 14.0. Acidity increases as the pH gets lower.
pH affects many chemical and biological processes in the water. For example, different organisms flourish within different ranges of pH. The largest variety of aquatic animals prefers a range of 6.5-8.0. pH outside this range reduces the diversity in the stream because it stresses the physiological systems of most organisms and can reduce reproduction. Low pH can also allow toxic elements and compounds to become mobile and "available" for uptake by aquatic plants and animals. This can produce conditions that are toxic to aquatic life, particularly to sensitive species like rainbow trout. Changes in acidity can be caused by atmospheric deposition (acid rain), surrounding rock, and certain wastewater discharges.
The pH scale measures the logarithmic concentration of hydrogen (H+) and hydroxide (OH-) ions, which make up water (H+ + OH- = H2O). When both types of ions are in equal concentration, the pH is 7.0 or neutral. Below 7.0, the water is acidic (there are more hydrogen ions than hydroxide ions). When the pH is above 7.0, the water is alkaline, or basic (there are more hydroxide ions than hydrogen ions). Since the scale is logarithmic, a drop in the pH by 1.0 unit is equivalent to a 10-fold increase in acidity. So, a water sample with a pH of 5.0 is 10 times as acidic as one with a pH of 6.0, and pH 4.0 is 100 times as acidic as pH 6.0.
Dissolved Oxygen
The stream system both produces and consumes oxygen. It gains oxygen from the atmosphere and from plants as a result of photosynthesis. Running water, because of its churning, dissolves more oxygen than still water, such as that in a reservoir behind a dam. Respiration by aquatic animals, decomposition, and various chemical reactions consume oxygen.
Wastewater from sewage treatment plants often contains organic materials that are decomposed by microorganisms, which use oxygen in the process. (The amount of oxygen consumed by these organisms in breaking down the waste is known as the biochemical oxygen demand or BOD.) Other sources of oxygen-consuming waste include storm water runoff from farmland or urban streets, feedlots, and failing septic systems.
Oxygen is measured in its dissolved form as dissolved oxygen (DO). If more oxygen is consumed than is produced, dissolved oxygen levels decline and some sensitive animals may move away, weaken, or die.
DO levels fluctuate seasonally and over a 24-hour period. They vary with water temperature and altitude. Cold water holds more oxygen than warm water and water holds less oxygen at higher altitudes. Thermal discharges, such as water used to cool machinery in a manufacturing plant or a power plant, raise the temperature of water and lower its oxygen content. Aquatic animals are most vulnerable to lowered DO levels in the early morning on hot summer days when stream flows are low, water temperatures are high, and aquatic plants have not been producing oxygen since sunset.
Conductivity
Conductivity is a measure of the ability of water to pass an electrical current. Conductivity in water is affected by the presence of inorganic dissolved solids such as chloride, nitrate, sulfate, and phosphate anions (ions that carry a negative charge) or sodium, magnesium, calcium, iron, and aluminum cations (ions that carry a positive charge). Organic compounds like oil, phenol, alcohol, and sugar do not conduct electrical current very well and therefore have a low conductivity when in water. Conductivity is also affected by temperature: the warmer the water, the higher the conductivity. For this reason, conductivity is reported as conductivity at 25 degrees Celsius (25 C).
Conductivity in streams and rivers is affected primarily by the geology of the area through which the water flows. Streams that run through areas with granite bedrock tend to have lower conductivity because granite is composed of more inert materials that do not ionize (dissolve into ionic components) when washed into the water. On the other hand, streams that run through areas with clay soils tend to have higher conductivity because of the presence of materials that ionize when washed into the water. Ground water inflows can have the same effects depending on the bedrock they flow through.
Discharges to streams can change the conductivity depending on their make-up. A failing sewage system would raise the conductivity because of the presence of chloride, phosphate, and nitrate; an oil spill would lower the conductivity.
The basic unit of measurement of conductivity is the mho or siemens. Conductivity is measured in micromhos per centimeter (µmhos/cm) or microsiemens per centimeter (µs/cm). Distilled water has a conductivity in the range of 0.5 to 3 µmhos/cm. The conductivity of rivers in the United States generally ranges from 50 to 1500 µmhos/cm. Studies of inland fresh waters indicate that streams supporting good mixed fisheries have a range between 150 and 500 µhos/cm. Conductivity outside this range could indicate that the water is not suitable for certain species of fish or macroinvertebrates. Industrial waters can range as high as 10,000 µmhos/cm.
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