Ambient Water Quality
Ambient water quality relates to water bodies such as lakes, rivers, and oceans. Water quality is the physical, chemical and biological characteristics of water. It is most frequently used to reference a set of standards by which compliance can be assessed. Water quality standards vary significantly due to different environmental conditions, ecosystems, and intended human uses.
On behalf of the City of Clearwater, Pinellas County monitors water quality within streams, lakes, and open water. Pinellas County publishes the results of the monitoring in the Ambient Monitoring Report. See Pinellas County's Water Resources website for a copy of the report.
Important indicators of water quality include the following:
- Chlorophyll-a: Water column chlorophyll-a concentrations are a measure of the quantity or biomass of planktonic algae or phytoplankton in a water body. Excessive nutrient loadings in a water body can result in high phytoplankton biomass conditions known as algae blooms. High algal biomass can greatly reduce water clarify, which in turn may limit the growth and distribution of desirable bottom vegetation such as seagrasses and can seriously degrade the aesthetic quality of a water body. In addition, persistent conditions of high algae biomass often result in die-off, sinking, and decay of the algae in water bodies. Decaying matter consumes oxygen and often results in fish kills.
- Dissolved Oxygen: Dissolved oxygen strongly influences where organisms live. Oxygen enters the aquatic environment from the atmosphere (wind, waves, direct diffusion), plant photosynthesis, and mixing and diffusion from more oxygenated water masses. A physical property of water is that the solubility of oxygen is greater in cold water than in warm water. Therefore, less oxygen can be dissolved in water as water temperature increases.
Biological factors such as increased metabolic rates and oxygen uptake rates of aquatic organisms may further reduce dissolved oxygen levels. Since biological oxygen uptake is often the greatest in bottom waters compared to surface waters, the first signs of an oxygen-stressed water body are usually observed as low bottom water dissolved oxygen levels. Such conditions often result in isolated or widespread fish kills.
- Fecal Coliform: Fecal coliforms, indicators of water column pathogens, are found in the intestinal tracts of animals and humans. Its presence can be natural or from man-made sources like sewage overflows or spills.
- Nutrients: Nutrients are chemical elements such as nitrogen and phosphorus that sustain life and promote growth. The amount of nutrients available in a water body is one of the controlling factors for plant growth. Waters containing few nutrients cannot support a large plant community and will not attract animal life, as there won't be a source of food.
Nutrients cause problems when they are overabundant. In particular, microscopic plants or algae, when under bloom conditions, may appear as green "clouds" in the water. The poor water clarity from such nutrient-induced algae blooms can limit water column light transparency, which in turn, will often limit available light necessary for desirable types of bottom vegetation, such as seagrasses, to grow.
- Total Suspended Solids: Total suspended solids are the amount of particulate material in the water including algae, sediments, and microorganisms. Total suspended solids affects the amount of light that can penetrate the water column and thus is part of what determines where plants grow. Increases in total suspended solids can be caused by algae blooms, increased runoff into a system, erosion, and by resuspension of bottom sediments in shallow areas.
(Indicator descriptions provided by Pinellas County Government)