Why do we have water quality standards?

Humans have populated almost every part of our planet. When human populations were low in number during the Stone Age, their impact to the land and water was minimal. However, as we have grown in population almost to the maximum holding capacity of the planet and with an advanced technology, we have also become very good at altering the environment on a large scale. In modern times, we can literally move mountains, change the way major rivers flow, pollute the oceans, and alter the climate. People realized during the last century that we need to have ecosystems that function naturally and healthily for humans to survive and thrive on earth. People want to be able to swim in water that is unpolluted. People also want to be able to catch fish that are healthy and abundant. In order to protect water resources from industrial pollution and the things people do on the land we created agencies, such as, the Louisiana Department of Environmental Quality (LDEQ) and the Environmental Protection Agency (EPA). This is why we have water quality standards.

How do we get to a water quality standard?

The Louisiana Department of Environmental Quality (LDEQ) in partnership with the EPA set standards for all of the major water bodies in Louisiana. There are 12 major river basins or watersheds in Louisiana. Each river basin has various sub watersheds within each. For each of these watersheds, LDEQ decides what the designated uses are for each state waterbody. Examples of designated uses are as follows:
Designated Use
Parameter Used for Standard
PCR = Primary Contact Recreation (swimming)
Fecal Coliform Bacteria
SCR = Secondary Contact Recreation (boating)
Fecal Coliform Bacteria
FWP = Fish and Wildlife Propagation (fishing)
Dissolved Oxygen
DWS = Drinking Water Supply
Fecal Coliform Bacteria
ONR = Outstanding Natural Resources
OYS = Oyster Propagation
Fecal Coliform Bacteria
AGR = Agriculture
LAL = Limited Aquatic Live and Wildlife
The designated uses of each water body then determine which parameter that a standard will be based on. Think of a parameter as a characteristic of a waterbody. A waterbody contains all sorts of things including dissolved oxygen, dissolved salts, nutrients, organic matter, algae, sediment, and fecal coliform bacteria (bacteria from the intestines of animals and birds). This is not necessarily bad and each water body characteristic or parameter can be important part of fueling the larger ecosystem. However, an excess or imbalance of certain parameters can be bad for the waterbody and the ecosystem. For instance, dissolved oxygen will have the most significant impact, compared to other parameters, on the health of fish and aquatic organisms. So, if a waterbody has low dissolved oxygen, it will probably lead to low fisheries productivity or fish kills. This is why standards have single parameters that relate back to the designated use.

Where do the numbers come from for water quality standards?

LDEQ and EPA use scientific studies to set values for standards. For example, in many waterbodies the primary contact recreation (swimming) standard is 100 colony forming units of fecal coliform bacteria per 100 mL. How did they come up with this number? Basically, it is an estimate of the amount of fecal coliform bacteria that the average person would have to swallow in order to make them sick. There are plenty conservative assumptions (the agencies weigh on the side of caution) with regard to age, body size, and the amount of time the swimmer spends in the water to get an estimate of the amount of water the average swimmer will ingest. Likewise, when standards are set for Fish and Wildlife Propagation (protection of fish) a number is established for dissolved oxygen. This value is based on scientific studies about populations of fish and their tolerance of oxygen levels. Once standards are established for each designated use of a waterbody, then regulations are put in place to prevent the excessive discharge of wastes that will negatively affect the health of waterbodies.

How is the health of waterbodies managed and protected?

There are two main types of water pollution, point sources and nonpoint sources. These are strange sounding words but there is a reason for it. When the original Clean Water Act (CWA) was written in 1972 the EPA was concerned with water pollution that came from factories, industrial discharges and municipal sewage plants. All of these were point source dischargers because the discharge from the factory was from a pipe or single point. These point source discharges were required to get a permit to discharge, regulated and fined if they exceeded their discharge permits.

Between the 1972 CWA and the reauthorization of the CWA in 1987, EPA had been monitoring the waters of the United States and found that point sources made up only a portion of the water pollution in the environment. From a management standpoint, all of these other pollution sources were labelled as nonpoint source pollution. However, from a practical standpoint non-point source pollution is the same as pollution carried by rainfall runoff.