By Friday, the count had skyrocketed to 93. On the Passaic River, there were four organisms per liter in the June 30 tabulation. If that wasn't the case, we'd be notifying the public. Algae are a problem for water supplies because they require treatment-plant operators to use more chemicals, which also drives up operational costs. It would cost even more, perhaps three times as much, to treat the Pompton River water.
Plant operators use alum to help settle the algae out of the water.
When more alum is used to remove the higher amounts of algae, more sludge is generated that has to be disposed of properly. Using more chlorine can increase the amount of cancer-causing trihalomethanes in drinking water. Trihalomethanes, also called disinfection byproducts, are formed when chlorine reacts with organic matter in the water. The concern over trihalomethanes has prompted the Environmental Protection Agency to draft new regulations to reduce the presence of the cancer-causing chemical in drinking water. Studies show an association between water with elevated levels of trihalomethane and early-term miscarriage, as well as bladder, rectal, and colon cancer.