Protecting the quality of water sources — for both drinking and recreation — is a year-round pursuit, but during the hot summer months, water utilities must contend with a few unique challenges brought on by warmer weather.
One of the most common summer water quality threats is the appearance of harmful algal blooms (HABs), masses of fast-growing algae triggered by warm temperatures, excess nutrients, and sunlight. HABs can form in all sorts of water sources, such as lakes and rivers, as well as estuaries and coastal areas. Fueled by excess nitrogen and phosphorus, the algae reproduce quickly, forming a scummy, foamy coating on the water’s surface. As the algae die, oxygen in the water is depleted, leaving little or none for aquatic life.
HABs are not only disruptive to the water body’s ecosystem but can also be toxic to humans, animals, and aquatic life. For example, exposure to a bloom of cyanobacteria, which is technically not algae but a plant-like bacteria that can perform photosynthesis, can cause a range of adverse reactions from skin, eye, nose and throat irritation to fever, stomach pain, vomiting — and in the most severe cases, death.
To protect the public from the dangers of HABs, the Centers for Disease Control (CDC) offers this simple advice: When in doubt, stay out. It’s impossible to tell if a bloom is toxic just by looking at it, so if one appears, people, pets, and livestock should steer clear.
Regular monitoring of drinking water sources is likely already part of water utilities’ source water monitoring programs. Equally important, however, is developing a protocol for detecting, assessing, and responding to HABs, as well as communicating risks and advisories to the public. Being prepared ahead of time will help minimize the impacts of HABs on your community.
Another water quality challenge that is exacerbated in summer months is maintaining adequate chlorine residuals in the distribution system. Temperature has a marked effect on chlorine: in warmer temperatures, it decays faster, which could lead to insufficient disinfection. Without enough disinfectant to kill waterborne pathogens and microorganisms, treated drinking water could pose a risk to customers.
Low chlorine residuals can also contribute to the formation of biofilm that can develop in pipes and attach to surfaces. Biofilm provides a cozy, protective shelter for microorganisms and can cause an array of water quality concerns, including taste and odor issues, corrosion and scaling, restriction of flow, pressure fluctuations, and waterborne disease.
Monitoring chlorine levels and adjusting dosage as needed will help combat the adverse effects of warm temperatures on disinfectant residuals.
Summertime is all about fun and enjoyment, but it’s also a time to be extra attentive to water quality. Vigilant monitoring and effective communication with the public can help ensure drinking water remains clean and safe for your community all summer long.