Summer Changes for E.coli Standards

A standard is something we can compare water quality data to in order to determine 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 that poses a potential threat to human and aquatic health, potentially leading to the water body being listed on the Alabama Department of Environmental Management (ADEM) 303(d) List of Impaired Waters. 

The Alabama Department of Environmental Management (ADEM) has water quality standards for many different variables, including dissolved oxygen, pH, turbidity, and pathogens, namely E.coli. 

E.coli is an indicator for pathogen pollution, more specifically, fecal contamination. Pathogens can cause serious illness to humans, and even death. 

Taking this into consideration, standards for recreational waters are based on the public’s seasonal use patterns. Rarely used areas have less chances of causing human health problems than frequently used areas. Because of this, they have higher allowable E. coli levels. 

Water quality standards for E. coli bacteria change in summer months for several Alabama waterbodies used for recreation, including waterbodies classified for Public Water Supply and Fish and Wildlife uses.  

Summer months are considered to be May through October. During summer months, the E. coli standard for Public Water Supply and Fish and Wildlife drops from 2,507 CFU/ 100 mL to 298 CFU/ 100 mL.  

The allowable level of E.coli for waterbodies classified as Swimming and Other Whole Body Water Sports  stays constantly low throughout the year, remaining at 235 CFU/100 mL. 

It is important to note that one unit of measurement commonly used for E. coli is “colony forming unit” abbreviated as CFUs. When discussing the level of E. coli in a waterbody, we also refer to a 100-milliliter sample.  

Curious of how you can find out what use classification your waterbody is? ADEM has maps available on their website: 

To simplify ADEM’s water quality standards, AWW uses a traffic light concept: green, yellow, and red lights.

Therefore, for AWW standards, water quality is meeting standards and poses a low risk to human health if the number of E.coli CFUs in 100 mL of water is between zero and 200. It gets the green light! 

We warrant caution and a yellow light if the number of E.coli CFU in 100 mL of water falls between 200-600.  

If the number of E.coli exceeds 600, STOP! There is a high risk of human contact and it gets the red light.  

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.  

Know Before You Go! 

Before you participate in water-related recreation, check out the following resources to make sure the waterbody is meeting water quality standards and puts you at low-risk for getting sick.