Pollutant Monitoring


There are several different classes of pollutants monitored by OEQ, including but not limited to solids, nutrients, metals, bacteria, pesticides, physical parameters, and organic matter.  Depending on the individual project goals some of these pollutants are monitored at different continuous monitoring stations at the locations indicated on the above map.  Sampling stations located on private property (SVB & EOF) are not identified on the above map. The ambient sites are maintained to provide long term hydrologic data and in case of the need to conduct water quality surveys at those locations in the future.  Project Study Plans (PSPs) describing each monitoring program in more detail can be found at the links below.  A general description of each of these parameters is presented below.

Ambient Stations and Submerged Vegetated Bed (SVB) Best Management Practice Effectiveness Monitoring PSP

Edge of Field (EOF) PSP

Pleasant Run PSP

Silt / Solids

When it rains, silt and suspended solids wash off fields, construction sites, roadways, parking lots and other areas into nearby streams. As a result of this, fish respiration can become impaired, plant productivity and water depth may be reduced, aquatic organisms and their habitats can be smothered, and aesthetic enjoyment of the water is reduced. Based on Ohio EPA’s Water Resource Inventory for the Year 2008, siltation is the leading cause of aquatic life impairment in the State of Ohio.  As part of its monitoring program, Clermont County measures concentrations of total suspended solids (TSS).


Nutrients are a class of pollutants that include various forms of nitrogen and phosphorus, which can be found in fertilizer, sewage, plant material, detergents, and wastewater effluent. Nutrients are necessary for plant growth. In excess levels, nutrients can lead to excessive growth of aquatic plants and algae, which in turn can deplete the stream of dissolved oxygen as they decompose, and block light to deeper waters. Low DO concentrations resulting from excessive nutrient loads can lead to a decrease in animal and plant diversity, and can affect our use of the water for fishing and swimming.

There are several different types of nutrients that can be monitored, including ammonia, nitrate+nitrite (NO3-NO2), total Kjeldahl nitrogen (TKN), total phosphorus and orthophosphate. Clermont County has collected and analyzed samples for each of these at numerous sampling sites since 1997.


Metals, such as copper and lead, may enter streams from industrial discharges, runoff from city streets, leachate from landfills, and a variety of other sources. These chemicals, which are generally persistent in the environment, can cause death or reproductive failure in fish and wildlife. In addition, they can accumulate in animal and fish tissue, be absorbed in sediments, or find their way into drinking water supplies, posing long-term health risks to humans.  Currently, OEQ does not routinely sample for metals, but can sample for metals if it suspects that there is a potential for metals contamination in a certain stream reach.


Bacterial organisms and other pathogens can enter waterways through a number of routes, including inadequately treated sewage, storm water drains, sanitary sewer overflows, failing on-site wastewater treatment systems (septic tanks), runoff from livestock pens and livestock entering streams, boats that dump sewage and wildlife. Because it is impossible to test water for every type of disease-causing organism, monitoring programs usually measure indicator bacteria such as fecal coliforms and E.coli that suggest the water may be contaminated with untreated sewage and that other, more dangerous, organisms may be present.

In 1997, Clermont County began monitoring fecal coliform concentrations at each of its sampling locations. Starting in 1998, the focus of the monitoring program shifted to E. coli. Each year, E. coli samples are collected at every sample location from May through October, when recreational activity in streams and lakes is the highest. In addition, the Clermont County General Health District monitors bacteria levels at the beaches in Harsha and Stonelick lakes.

Physical Parameters

OEQ collects various physical parameters such as pH, water temperature, specific conductance, turbidity, oxidation reduction potential, and dissolved oxygen at five of the water quality stations.  We use specific conductance to determine when baseflow conditions are occurring at Pleasant Run but it can also be used to identify areas high in raw sewage or salt runoff.  We use oxidation reduction potential to help identify periods of time when the SVB may be undergoing nitrification or denitrification.  Turbidity can be an indicator of phosphorus loading and is monitoring at the East Fork of the Little Miami directly upstream from Harsha Lake to get a handle on continuous phosphorus loading to the lake.

Organic Enrichment / Dissolved Oxygen

Organic material may enter waterways in many different forms as sewage, as leaves and grass clippings, or as runoff from livestock feedlots and pastures. When natural bacteria and protozoans in the water break down this organic material, they begin to use up the oxygen dissolved in the water. Many types of fish and bottom-dwelling animals cannot survive when levels of dissolved oxygen drop below 2 to 5 parts per million (mg/l).

At all sampling locations, OEQ directly monitors the instream dissolved oxygen concentrations.  OEQ also has the ability to measure CBOD5, the 5-day carbonaceous biochemical oxygen demand (CBOD5) concentration. This represents a measure of the amount of dissolved oxygen consumed in five days by biological processes breaking down organic matter.

Hydrology Data

At all of the continuous monitoring stations, stream stage and rainfall data are collected on 15 minute intervals.  This data helps OEQ identify areas of flooding and quantify the volume of water, or discharge, running off of an area of land.  The discharge data is used to determine the amount of pollutant loading (weight of pollutants) coming from a watershed and is helpful in determining where best management practices should be placed to help reduce pollutant loading and minimize harmful algae blooms and degradation to aquatic communities.   Some of the hydrology data is made public at this link.  The username and password are “public”.