Water Quality Parameters 101
Thursday, February 22, 2017
Maintaining a healthy gulf is an important goal for the State of Mississippi. In our previous blog,
“Improving water quality on the Mississippi Gulf Coast”, we discussed different types of pollution that
can impair water quality, but how can you tell if a water body is impaired? There are numerous water
quality indicators that are used to determine the health of a water body. Some of these measurements
can be taken on site, while others are collected and analyzed in a laboratory. After the samples have
been analyzed, the data is used to assess the health of the body of water by comparing it to a specific
water quality standard that is set by the State. More information on Mississippi’s water quality
standards can be found here.
On-site Parameters
On-site parameters are taken and recorded directly at the site. There are
several parameters that fit this category, including temperature, pH, dissolved
oxygen (DO), and turbidity. Temperature is an important parameter as it
affects so many different aspects of water quality, including biological and
chemical reactions, solubility of chemical species, and density of the water. It
can be affected not only by the season but also by groundwater, discharges,
and weather. pH represents how alkaline or acidic a water body can be and is
measured on a scale from 0-14. A pH of 7 is balanced or neutral. Lower than
7 means that the water is acidic, and higher than 7 is alkaline or basic. The pH
of water can have a negative impact on the aquatic life in a water body if it is
too acidic or too basic. DO is a measurement of how much oxygen is dissolved
Figure 1MDEQ field technician in the water and is typically measured in milligrams per liter (mg/L) or percent
takes water quality
saturation. Aquatic organisms cannot live without oxygen, so this parameter
measurements on the
Mississippi Coast.
is one of the most significant indicators of water quality. DO can enter a water
body in two ways: turbulence from wind or waves or photosynthesis of plant
material which creates oxygen as a by-product. Turbidity is measured in Nephelometric Turbidity Units
(NTU’s) and is an assessment of the ability of light to pass through water. It is caused by suspended solids
floating in the water. Suspended solids occur naturally in water and include silt, clay, and organic particles
such as algae. Increased suspended solids can be from erosion or effluent discharges. High turbidity can
signify that there is not enough light to reach plant life in the water body, which can affect the
photosynthesis process and, therefore, minimize the amount of DO produced.
Lab Parameters
Some parameters need to be sampled and preserved at the site and analyzed at a laboratory, including
nitrogen, phosphorus, and fecal bacteria. Nitrogen and Phosphorus are plant nutrients, measured in
mg/L. High concentrations of these nutrients can cause extreme growth of plants and algae in water
bodies, which can lead to low DO levels that negatively impact aquatic animal life. These nutrients can
enter water body systems via fertilizers, wastewater discharge, car washes, and agricultural runoff. Lab
results reveal the amounts of total nitrogen and total phosphorus, as well as a breakdown of their many
forms, to give a clear picture of potential nutrient issues. Fecal bacteria naturally occur in the intestines
of humans and animals. They enter water body systems through outflow of wastewater treatment
plants, septic systems, storm water runoff, and animal waste. They serve as an indicator of other
microorganisms that can cause harm to human health. Fecal bacteria are measured in the lab by
incubating a sample for 24 hours and counting how much bacteria grew in that amount of time, usually
in organisms/100 mL.
These examples are just a few of the types of water quality parameters that are used to assess water
bodies. Identifying an impaired water body is a complicated process that is taken very seriously by the
State of Mississippi. In our FAQs section of the Beach Outfalls Challenge website, we have provided
water quality data for a few beach monitoring sites in Gulfport, MS, to give you can idea of what the
water quality is like on the Mississippi Gulf Coast.
A successful Beach Outfalls Challenge could help improve water quality and benefit the ecology of the
Mississippi Sound, as well as remedy harm to natural resources harmed by the Deepwater Horizon oil
spill. MDEQ is looking for practical, implementable, eco-restoration solutions that will improve water
resources. Do you have a great idea? Registration for the Beach Outfalls Challenge is now open! Learn
more about the Beach Outfalls Challenge by visiting the ABOUT Page of our website. CLICK HERE to
receive periodic updates about the Beach Outfalls Challenge.