The worst U.S. drought since 1956 has been affecting the taste, smell and appearance of tap water across the country. So far officials in places as far flung as Southern California and Connecticut claim that drought-caused water quality problems are an issue of taste and smell, not safety.
In Texas, Wichita Falls Utilities Operations Manager Daniel Nix explains that there is a difference between “potable” and “palatable.” Potable means the water is safe to drink. Palatable refers to the quality of taste and smell. Nix concedes some people are finding their tap water less than palatable.
1. Drought Worsens Sediment Runoff During Much-needed Rainfall
Parched earth does not absorb water as well soil that already contains some moisture. When summer storms cause sudden rainfall, more soils in drought stricken areas wash into rivers and streams than would have in non-drought conditions. Additional sediment can cause what’s known as turbidity problems, when particles suspended in the water give it a cloudy appearance. While unsettling, high turbidity isn’t necessarily dangerous. However, high turbidity must be reduced by a water utility. There is a Safe Drinking Water Act standard for turbidity because the condition sets utilities up for other problems, including bacterial growth within the distribution system (see points 2 and 3).
2. Warm Surface Water and Extra Sediment Encourages Algae and Bacteria Growth
Even northern lakes not known for algal blooms are seeing them this year. Lower the usual water levels, higher than usual temperatures, and extreme storm which dumped unusual amounts of sediment into Lake Superior set up conditions for extremely unusual blue-green algae, or pond-scum, growth in the lake.
Wisconsin pubic health officials are concerned that the algae “can produce cyanotoxins that remain in the lake for weeks—long after the algae bloom disperses. These toxins can pose numerous health risks for aquatic–bound life, including humans, if it comes into contact with the skin, or is ingested.
Warm water also causes bacteria growth in rivers and lakes: “While most algal and bacterial blooms are not toxic, it is nearly impossible to identify poisonous species without a laboratory analysis of a sample.”
Extra bacteria and unusual algae means water utilities and natural resource officials must add extra treatment chemicals to water supplies. Extreme chlorination is one of the complaints of residents in Darien, Connecticut, where discolored water and conflicting advice from authorities is alarming residents. A major algal bloom also hit the water supply in Southern California in July.
3. Lower Water Levels Mean Higher Contaminant Concentrations
As the quantity of water in reservoirs and lakes fall, concentrations of dissolved toxins rise. Nitrates, sulfites and any other soluble chemical dumped into waterways could be drawn into drinking water supplies at a higher ratio than normal, burdening filtration plants.
Officials in hard-hit Texas are concerned that water levels are so low that quality could “so degraded that advanced treatment measures, like reverse osmosis, would be required to produce clean supplies of sufficient quality,” said Samantha Heng, a Texas Water Development Board spokeswoman.
4. Increased Acidity of Water Ways Intensifies Toxic Effects on Wildlife
Humans are not the only creatures affected by drought-related water quality problems described above, but a recent study out of Baylor University shows gives us another reason to worry about wildlife during droughts. “As water levels drop, acidity levels of surface waterways increase. “The study found that drought conditions exacerbate the magnitudes of the natural pH shifts in the water. This is important, the researchers said, because some contaminants in the water, such as ammonia, are more toxic to aquatic life depending on the pH level.” Approximately a third of modern pesticides and many pharmaceutical drugs react this way and can “become more toxic to fish when surface pH levels are high.”