River Monitoring Project


Urban and suburban rivers are - almost by definition - degraded waters. Therefore, scientists and environmentalists don't monitor them to find out if they are polluted, but rather to find out how polluted they are, and with what.

For over a decade, the River Prairie Group (Sierra Club's local chapter in DuPage County, Illinois) has monitored the water quality of three regional rivers - Salt Creek and the east/west branches of the DuPage River - as part of Sierra Club's national Water Sentinels project. Our all-volunteer effort, one of the oldest and broadest programs of its type, tests river water each month and posts it to this webpage (below) in an integrated spreadsheet/graphical format.

Test results are compiled in site-specific, chronological format dating back over ten years. Rivers benefit from such long-term monitoring by enabling their data to:

  • Act as a general barometer of the rivers, and indirectly, of its inputs (point and nonpoint).
  • Highlight upstream and downstream differences.
  • Track the impact of seemingly unrelated events. For example, when the Chicago Tribune ran articles during the heavy snowfall of 2008 investigating the ramifications of increased road salting, they referenced our data to track the corresponding chloride increases in the rivers.
  • Transform a body of data into a historical record within which long-term trends in stream quality can be identified, such as seasonal and year-to-year variations.
  • Transform a body of data into a historical record against which the rivers' health can be compared in the future. This enables a before-and-after assessment of a structural transformation in the watershed, such as a dam removal or a change in land use within the watershed or riparian corridor.
  • Provide a public service for the community. Due to federal and state budget cuts, governmental monitoring of some rivers was curtailed, leaving the Sierra Club as the solo monitor. Additionally, we are the sole investigators of pharmaceuticals in the DuPage rivers!
  • Provide a free and publicly accessible repository of data. We are fully transparent in posting all raw data on this publicly-accessible website where it can be downloaded by citizens, educators, researchers, policymakers, the media, and other environmental organizations.
  • Provide context for similar projects in other states.
  • "Think globally, act locally." As sub-tributaries to the Mississippi River, our three rivers carry water and contaminants to the Gulf of Mexico; as such, our data is utilized to influence local policy. We regularly present our findings to city, county, and state policymakers, including the Illinois EPA, which establishes Total Maximum Daily Load (TMDL) limits for pollutants in our rivers in compliance with section 303(d) of the Clean Water Act. Additionally, our three rivers are tributaries to the Des Plaines River, which has been identified by the State as an impaired waterway (a waterway that does not meet water quality standards), so our data is relevant to that TMDL study as well. (TMDL limits and impaired waterways are detailed on the U.S. EPA website .)
Pollutants Monitored

The Group is currently analyzing the water samples for the following pollutants: phosphorus, chloride, ammonia, and nitrates. The pollutant standards presented are Illinois' general use water quality standards, which would apply to the waterways monitored in this project. Please note that such standards do not exist for all of the pollutants monitored in this project.


Phosphorus is one of the key elements necessary for animal and plant growth. Phosphates (PO4---) are formed chemically through the oxidation of this element. Phosphates exist in three forms, orthophosphate, polyphosphate, and organically bound phosphate, with varying formulations involving phosphorus. Ortho forms are formed naturally. Poly forms are used in detergents and in the treatment of boiler water. Organic phosphates may result from the breakdown of organic pesticides containing phosphorus. Rainfall causes varying amounts of phosphates and phosphorus to wash from farm soils and soils treated with certain pesticides into waterways.Phosphates stimulate the growth of algae and aquatic plants that provide food for fish. This may cause an increase in the fish population, benefiting aquatic lifeforms. Excess phosphates, however, may cause an excessive growth in algae and aquatic plants, choking waterways and using up large amounts of oxygen, referred to as eutrophication. The death of the algae and aquatic plants results in the additional consumption of oxygen. The decrease in oxygen levels can result in the death of aquatic life.Phosphates are not directly toxic to humans or animals unless they are present in very high concentrations. Digestive problems, however, can result from high levels of consumed phosphates. The main concern related to phosphates is the potential for eutrophication.There is no Illinois general use water standard for phosphates.


Chlorides are salts resulting from the combination of the gas chlorine and various metal ions. Chlorine alone as Cl2 is very toxic. In combination with a metal ion, such a sodium (Na), it becomes essential for life. Small amounts of chlorides are essential for normal cell function.Despite their beneficial impacts on cell function, chlorides can contaminate fresh water streams and lakes. Fish and other aquatic life forms cannot survive in high levels of chorides. Chlorides may enter surface water from sources such as : (1) rocks containing chlorides; (2) agricultural runoff; (3) industrial wastewater; (4) oil well wastes; (5) wastewater treatment plant effluents; and (6) road salts.The Illinois general use water standard for chlorides is 500 milligrams per liter (mg/L) for chronic (long-term) exposures (not to be exceeded by the arithmetic average of at least four consecutive samples collected over any period of at least four days).Many winter test samples exhibit elevated levels of chlorides, the result of road salt runoff after a snowfall.


Ammonia (NH3+) is a gas which is fairly soluble in water, and reacts with it to form a weak base. One unit of water can dissolve many units of ammonia.Approximately three-fourths of the ammonia produced in the United States is used in fertilizers as ammonia itself or as ammonium salts of nitrates or sulfates. Large quantities of ammonia are used to produce nitric acid, urea, and other nitrogen compounds used in many chemical processes. Ammonia is also used in the production of ice and as a refrigerant. An aqueous solution of ammonia is used to remove carbonate from hard water.Since ammonia is also a decomposition product from the reaction of urea and protein, it is found in domestic wastewater. Fish and other aquatic life forms contribute to the production of ammonia in streams and other water bodies.Non-ionized ammonia (NH3) is the principal form of toxic ammonia. It has been determined to be toxic to freshwater organisms in concentrations in the threshhold range of 0.53 to 22.8 mg/L. Toxic levels are both pH and temperature dependent. Toxicity increases with decreasing pH (as the water becomes more acidic and less basic) and as the water temperature decreases. Hatching and growth rates of fishes may be negatively affected by increases in non-ionized ammonia. Structural development detrements in the tissues of gills, livers, and kidneys may also occur with increasing non-ionized ammonia concentrations.The State has established a total ammonia limit (measured as nitrogen, N) of 15 mg/L, and our samples show no total ammonia concentrations near this limit. The State has established seasonal chronic exposure limits for non-ionized ammonia of 0.057 mg/L for April through October and 0.025 mg/L for November through March. We monitor total ammonia, as well as pH and temperature, to allow us to determine the concentrations of non-ionized ammonia.


Nitrogen-containing compounds act as nutrients in streams, rivers, and reservoirs. The major sources of nitrogen in water are municipal and industrial wastewater, septic tanks, feedlot discharges, animal wastes (livestock, birds, mamals, and fish), fertilized field and lawn runoff, and vehicle exhausts (exhausts are sources of N2 and oxides of nitrogen). Nitrogen in water can be oxidized to nitrites (NO2-). Bacteria in water converts nitrites to nitrates (NO3-) through a process which ties up the available oxygen in water.Nitrate levels in water fluctuate by season, with Spring concentrations usually higher after snowmelt. Higher nitrate levels also occur following heavy rainfall.The major impact of nitrates and nitrites on fresh water bodies is that of fertilization leading to possible eutrophication. Nitrates stimulate the growth of algae and plankton, but excessive levels of nitrogen can cause overproduction of algae and plankton. When the algae and plankton die, they decompose and consume oxygen. The consumption and eventual depletion of oxygen can lead to the suffocation of other organisms.There is no Illinois general use standard for nitrates.



The temperatures reported here are those monitored during the sample collection.

The temperature of the water can have many effects. First, the temperature range of the water can significantly affect which fish will survive or thrive in the water. Second, the temperature, amongst other factors, can affect the amount of disolved oxygen in the water, which in turn can affect the various lifeforms in the water. Third, the temperature of the water can affect algae growth in the water. Finally, the temperature of the water can affect the level of certain chemical ions in the water, which in turn can affect the fish within the water. Generally, relatively high water temperatures are detrimental to desirable fish populations.