Msad 61 Crooked River School

What it means: Diquat is a broad-spectrum contact herbicide used to control aquatic weeds, algae, and terrestrial vegetation. It remains in active use in the United States, applied directly to water bodies and irrigation canals. Diquat binds tightly to soil but can enter surface water directly during aquatic applications.

Health effects: Chronic exposure to diquat is associated with cataracts and kidney damage in animal studies. Acute high-level exposure causes gastrointestinal distress. EPA has not classified diquat as a human carcinogen. Individuals with kidney conditions may be at elevated risk from chronic exposure.

Limit: 0.02 mg/L (20 ppb)

What it means: Endothall is an aquatic and terrestrial herbicide used to control algae, weeds, and grass in irrigation canals, ponds, and lakes. It is still in use in the United States and is applied directly to water bodies for aquatic vegetation management. It degrades relatively quickly in aquatic environments but can appear in source water shortly after application.

Health effects: Short-term exposure above the MCL can cause gastrointestinal irritation and stomach cramps. Chronic exposure is associated with liver, kidney, and gastrointestinal damage in animal studies. EPA has not classified endothall as a human carcinogen. The general population is at risk from water system violations.

Limit: 0.1 mg/L (100 ppb)

What it means: The 2013 RTCR (effective 2016) replaced the original TCR. It triggers automatic E. coli testing whenever total coliform is found. A single E. coli-positive sample is an acute MCL violation. It also requires systems exceeding 5% total coliform-positive samples to conduct a formal assessment and correct any deficiencies, helping prevent contamination before it escalates.

Health effects: Total coliform bacteria indicate that the disinfection barrier has been breached or fecal contamination is entering the system. E. coli specifically indicates fecal contamination and the possible presence of disease-causing pathogens (norovirus, Salmonella, Shigella, Campylobacter). Illness can be severe in elderly, young children, and immunocompromised individuals.

Limit: Zero E. coli; ≤5% of monthly samples total coliform-positive