Overview of Variables Tested by Alabama Water Watch Volunteers

This article will provide an overview of all of the variables tested by certified Alabama Water Watch volunteer monitors, what the data mean. To know whether or not the data indicate water quality issues, it is necessary to have some understanding of Water Quality Standards, so we’ve briefly explained Water Quality Standards for Alabama. The information included could be helpful for interested volunteers who are trying to get started as monitors, people who want to learn more about water quality in their watershed, or certified volunteers who are reviewing the data at their sites.

What are water quality standards? 

A standard is something we can compare water quality data to in order to know if the quality of that water is good or bad. If water quality data results consistently fail to meet the standards, there may be a chronic problem with water quality. 
Some water quality standards are usually based on what conditions are needed for aquatic life to survive. These water quality standards are designed to protect, restore, and maintain water quality. 

What are Water use classifications? 

Water use classifications are the “reasonable and necessary uses” of a waterbody as defined by the Clean Water Act. Waterbodies can be classified as the following: 

  1. Outstanding Alabama Water (OAW) 
  1. Public Water Supply 
  1. Swimming & Other Whole Body Water-Contact Sports (S) 
  1. Shellfish Harvesting 
  1. Fish & Wildlife (F&W) 
  1. Limited Warmwater Fishery 
  1. Agricultural & Industrial Water Supply (A&I) 

What do Alabama Water Watch Volunteer Monitors test? 

Bacteriological Monitoring 

Volunteer Monitors detect levels of E. coli and other coliform bacteria in water as indicators of fecal contamination. Monitors are trained in bacteriological sampling (site selection, plating and incubating samples, and counting bacteria colonies) and water quality standards.  

E. coli 

Escherichia coli (E. Coli) is a single species of fecal coliform that exists in about 700 forms, or strains. The vast majority are harmless, but a few are highly pathogenic. 

The presence of E. coli in food or water is a sure sign of fecal contamination.  

Other coliforms 

Alabama Water Watch uses a simple, inexpensive, and accurate method to quantitatively identify the presence of E. coli. The concentration of E. coli cells, or the number per unit volume of water is directly related to the probability that the water also carries other disease-causing pathogens. Therefore, if E. coli is present in a waterbody, it is possible that other pathogenic bacteria, viruses, protozoa, etc. are also present. 

The bacteriological test used by AWW does not distinguish the source of E. coli, whether it be human, livestock, wild animals, etc. Citizens can get a general idea of the potential source of E. coli in their samples by surveying land use surrounding the sample site.   

Water Quality Standards for E. coli in Water 

AWW wants to be reasonable and conservative with our standards, so we use a stoplight method for interpreting bacteriological data where we consider water to meet water quality standards if the number of E. coli colony forming units (CFU) in 100 mL of water is between zero and 200. We warrant caution if the number of E. coli CFU in 100 mL of water falls between 200 and 600. If the number of E. coli falls above 600, there is high risk for human contact.   

From May to September, anything above 300 E. coli CFU per 100 mL does not meet standards for Swimming and Other Whole Body Water Sports.    

High E. coli levels indicate contamination from wildlife, runoff containing pet manure, agricultural runoff, wastewater treatment plants, and on-site septic systems. Human contact with such water can cause gastrointestinal illness, skin, ear, respiratory, eye, neurologic, and wound infections. Excess bacteria and other decomposers reduce DO levels in water as they consume oxygen while breaking down organic matter. 

Water Chemistry Monitoring  

Volunteer Monitors test physical and chemical characteristics of water to identify pollution sources and long-term trends in water quality. Six variables (listed below) are measured with a customized test kit and results can be compared with water quality standards that define conditions for healthy waterbodies.  

Air and Water Temperature 

Temperature affects the physical and chemical properties of water, which can influence the feeding, reproduction, and metabolic rates of aquatic organisms.  

Aquatic organisms, like fish, have different tolerances to changes in temperature:  

Temperature guild Species Optimum range °C Upper lethal limit °C 
Coldwater Rainbow trout 13 – 21 24 – 28 
Coolwater Yellow perch 19 – 21 21 – 30 
Warmwater Channel catfish 21 – 27 30 – 35 
Tropical Blue tilapia 23 – 30 29 – 39 

There are many natural and human factors that can affect water temperature, including: change in the season, groundwater, springs, shading by vegetation, clearing of the riparian zone, industrial and power plants, and runoff from heated surfaces.  


pH is a measure of how acidic or basic a solution is.  

Low pH levels reduce the solubility of calcium carbonate inhibiting shell growth in aquatic organisms. Fish struggle to reproduce, become susceptible to fungal infections and other physical damage, and if pH drops below 4.0 is deadly. Amphibians are vulnerable to low pH, probably because their skin is sensitive to pollutants. Streams draining forests and marshes are often slightly acidic due to the presence of acids produced by decaying vegetation in the soil. 

High pH levels in water can damage gills and skin of aquatic organisms, cause inability to dispose metabolic waste, and cause death at levels over 10.0. Since photosynthesis occurs only when light is present, the highest pH in waterbodies with dense algae often occurs in the late afternoon. A shift of pH in either direction from neutral may indicate the presence of a pollutant in the stream. 

Total Hardness 

Hardness is related to the amount of calcium and magnesium are in water. Calcium and magnesium help support animal and plant life. Plants use calcium to develop cell walls and magnesium for photosynthesis, and animals use calcium for shells and bones.  

Aquatic organisms can tolerate a broad range of hardness. Most of them live in waters with total hardness between 15 and 200 mg/L.  

High hardness levels may indicate the influence of human activity in the area. Drainage from mines can contribute calcium, magnesium, iron, manganese, and other ions. This can increase the hardness of a stream. Industrial processes may also produce significant amounts of calcium and manganese, and effluents from wastewater treatment plants discharged to streams. Hard waters usually have a high pH. 

Total Alkalinity 

Alkalinity is a measure of the buffering capacity of water. Water with low alkalinity is susceptible to rapid changes in pH and is therefore less stable for aquatic life.  

Limestone is a natural source of both hardness and alkalinity. The chemical name for limestone is calcium carbonate (CaCO3) or magnesium carbonate (MgCO3). The carbonate (CO3) and bicarbonate (HCO3) ions in dissolved limestone are a natural source of alkalinity.  

In areas with no industrial impacts, total hardness and total alkalinity values tend to be very similar.  

Waterbodies with little to no alkalinity have less capacity to neutralize acids and because of this, pH can drop below the optimal range for aquatic life (between 6.5 and 8.5), acidifying the water. Changes in pH increase toxicity of certain chemicals, cause harm, stress, and death to fish and other aquatic life.  

High alkalinity may indicate runoff from lawns where owners apply limestone to raise the soil’s pH and improve lawn growth. Excessive limestone reaching streams may greatly increase water pH, and reach dangerous levels for aquatic life. A sudden change in pH of 1.5 unit or higher in water could kill about 50 percent of the fish in the water.  

Dissolved Oxygen 

Just like humans, aquatic plants and animals need oxygen to survive. Dissolved oxygen is the amount of oxygen available to aquatic life in water.  

Oxygen can enter a waterbody physically through riffles, waterfalls, and other disturbance at the water’s surface and biologically through photosynthesis of aquatic plants. 

Low dissolved oxygen levels in streams may be because a) the water is too warm; b) there are too many bacteria and a high biological oxygen demand; or c) excessive algae growth (caused by excess nutrients) which when it dies and decompose, consumes DO. Extended low DO levels may result in fish kills and loss of other aquatic life like caddisfly, and stonefly nymphs.  


Turbidity is a measurement of water clarity. 

High turbidity indicates soil erosion, runoff, discharges, stirred sediments or algal blooms. It can increase water temperatures and decrease dissolved oxygen levels, inhibit photosynthesis by blocking sunlight, and choke aquatic organisms. Sediments can carry bacteria, protozoa, nutrients (ex. Nitrates and phosphorus), pesticide, mercury, lead and other materials, and cover streambed gravel in which aquatic life lay eggs, killing those eggs. 

Secchi Disk Depth 

Secchi disk depth is used as an indicator of water quality related trophic status and is an indirect measurement of chlorophyll concentration, oxygen depletion rate and fish yield. Secchi depth is recommended to be measured on a weekly basis.

Low Secchi Depth values mean the water has less clarity (is more turbid) indicating pollution. Watershed development and poor land use practices cause increases in erosion, organic matter, and nutrients, all of which cause increases in algae growth. Nitrogen and phosphorus entering a stream provide more food available for algae, so algal concentrations increase, the water becomes less transparent (cloudier) and the Secchi Disk Depth decreases. 

Stream Biomonitoring 

Volunteer Monitors assess macroinvertebrate communities in steams (aquatic insects, snails, worms, etc.) as water quality indicators. Volunteers conduct field collections of macroinvertebrates to calculate a biotic index of stream quality.  

The presence or absence of several types of benthic macroinvertebrates is one of the best ways to assess the level of human disturbance and pollution in streams and rivers (i. e. stream health) for several reasons. Each species has unique characteristics regarding habitat requirements, life history, behavior, and pollution tolerance.  

The Biotic Index 

The Biotic Index (BI) of water quality is based on the pollution tolerance of each type of macroinvertebrate found in the sample; therefore, giving more importance to diversity than to abundance. The number of any type is not directly used to calculate the BI, but knowledge of their abundance (rare, common, or abundant) is important for understanding water quality conditions and trends.