Weatherford

What it means: Arsenic is a naturally occurring metalloid found in bedrock and soil. It dissolves into groundwater from natural deposits and can also come from mining, smelting and past pesticide use. EPA lowered the MCL from 50 ppb to 10 ppb in 2001.

Health effects: Long-term arsenic exposure increases risk of bladder, lung, and skin cancers. It is also associated with cardiovascular disease, type 2 diabetes, and developmental effects in children. Arsenic is classified as a Group A human carcinogen by the EPA.

Limit: 0.010 mg/L (10 ppb), set in 2001 and enforceable since 2006; the previous MCL was 0.050 mg/L (50 ppb)

What it means: This entry tracks violations of the Maximum Residual Disinfectant Level (MRDL) for chlorine — meaning too much disinfectant residual in the distribution system, not too little. Chlorine is added to water to kill pathogens, but excess residual can react with organic matter to form disinfection byproducts.

Health effects: Acute high-dose exposure to chlorinated water can cause eye and nose irritation, stomach discomfort, and nausea. Chronic exposure above the MRDL is primarily a concern because elevated chlorine accelerates formation of trihalomethanes and haloacetic acids, which are associated with increased cancer risk over time.

Limit: MRDL: 4.0 mg/L as an annual average

What it means: Radium-226 and Radium-228 are naturally occurring radioactive isotopes produced by the decay of uranium and thorium in bedrock. They dissolve into groundwater, particularly in deep aquifers with low oxygen and low pH. Granite bedrock and some deep sandstone and limestone aquifers present conditions where combined radium can reach detectable levels in drinking water.

Health effects: Radium is a bone-seeking radionuclide that accumulates in skeletal tissue after ingestion. Long-term exposure increases the risk of bone cancer and leukemia. There is no safe threshold for ionizing radiation — the MCL is set at a level balancing risk reduction with treatment feasibility. Children are particularly vulnerable due to higher rates of bone growth and calcium uptake.

Limit: 5 pCi/L (combined Ra-226 and Ra-228)

What it means: Uranium is a naturally occurring radioactive heavy metal found in rock and soil formations across the United States. It leaches into groundwater through weathering of uranium-bearing minerals, and is more prevalent in granite-rich and other uranium-bearing geologies. Mining and milling operations can also elevate uranium in nearby water supplies.

Health effects: Uranium poses both radiological and chemical health risks. Chronic exposure is primarily associated with kidney damage due to its chemical toxicity as a heavy metal. The radiological risk — increased cancer probability — is also present but secondary to the nephrotoxic concern at drinking water concentrations. There is no safe threshold for radiation exposure.

Limit: 0.030 mg/L (30 µg/L)

What it means: Gross alpha particle activity is a screening measurement of all alpha-emitting radionuclides in water, excluding radon and uranium (which are regulated separately). If gross alpha exceeds 5 pCi/L, further analysis is required to identify specific radionuclides. Elevated gross alpha typically indicates water drawn from deep aquifers in contact with uranium- or thorium-bearing bedrock.

Health effects: Alpha-emitting radionuclides accumulate in bone and soft tissue, delivering sustained internal radiation doses that increase lifetime cancer risk. There is no established safe threshold for ionizing radiation. Individual contributors such as radium-226 and polonium-210 have their own MCLs; gross alpha serves as a cost-effective screening tool that triggers more specific radionuclide analysis when exceeded.

Limit: 15 pCi/L (excluding radon and uranium)

What it means: Gross beta particle activity is a screening measurement of beta-emitting radionuclides in water, such as strontium-90 and tritium. Monitoring is required mainly for systems the state designates as vulnerable to man-made radioactivity, for example those near nuclear facilities, and most systems test only every few years. When the screening level is exceeded the system must identify the individual radionuclides.

Health effects: Beta and photon emitters deliver a radiation dose when ingested. Long-term exposure increases the risk of cancer; strontium-90 concentrates in bone and tritium is distributed through body water. The limit is a dose-based standard rather than a concentration.

Limit: 4 millirem per year to the total body or any organ; a gross beta screening level of 50 pCi/L triggers identification of the specific radionuclides

What it means: TTHMs are four compounds — chloroform, bromodichloromethane, dibromochloromethane, bromoform — formed when chlorine reacts with organic matter in water. They are among the most common disinfection byproducts and form more readily in surface water systems with high organic loads.

Health effects: Long-term exposure is associated with increased bladder cancer risk. Some studies link high TTHM exposure to adverse reproductive outcomes. Bromodichloromethane is classified as a possible human carcinogen.

Limit: 0.080 mg/L (80 ppb) locational running annual average (LRAA)

What it means: HAA5 are five haloacetic acids formed when chlorine disinfectants react with naturally occurring organic matter in source water. Higher levels occur with more organic-rich source water or when water sits longer in distribution pipes. The violation indicates the locational running annual average exceeded the MCL.

Health effects: Dichloroacetic acid is a probable human carcinogen (Group B2). Long-term exposure to trichloroacetic acid may also increase cancer risk. Animal studies show liver, kidney, and reproductive effects at high doses.

Limit: 0.060 mg/L (60 ppb) locational running annual average (LRAA)