The U.S. Environmental Protection Agency has established new water quality criteria for aluminum to protect aquatic life in Oregon. Aluminum is present in the environment naturally in most rocks and is associated with many clays, soils, and sediments. Human activities such as fossil fuel combustion, aluminum production, and the use of fertilizers in agriculture can also release aluminum into the environment.
In 2004, Oregon adopted aquatic life criteria for aluminum based on EPA's 1988 national recommended criteria. In 2013, EPA disapproved the aluminum criteria submission from the state. Since that time, EPA has updated its national recommended criteria. As a result of litigation, EPA must approve or establish new aluminum criteria in Oregon by Dec. 31, 2020.
EPA has posted the new aluminum criteria rule on their website (see link below) and expects to publish the new rule and preamble in the federal register in January 2021. DEQ anticipates that the federal criteria will become effective in Oregon for Clean Water Act purposes 30 days after it is published in the federal register.
The EPA's aluminum criteria for Oregon are based on EPA's 2018 final Clean Water Act section 304(a) national recommended freshwater aquatic life criteria for aluminum (see the link to EPA's criteria document below). The aluminum standard is a set of equations included in EPA's Aluminum Criteria Calculator. The calculator derives instantaneous aluminum criteria, which change based on water chemistry, including pH, dissolved organic carbon, and hardness levels. These parameters affect aluminum toxicity because they change aluminum bioavailability. Bioavailability describes whether a chemical form is accessible to an organism. For example, aluminum is more bioavailable to aquatic organisms when it is dissolved in the water than when it is bound within rocks. Input parameters (pH, dissolved organic carbon, and hardness) are entered into the Aluminum Criteria Calculator to determine the instantaneous criteria for a given set of water chemistry conditions. The aluminum criteria are the output of the Aluminum Criteria Calculator.
Aluminum standard application
Aluminum bioavailability, and therefore toxicity, is affected by pH, dissolved organic carbon, and hardness. DEQ is reviewing the pre-publication federal aluminum rule for Oregon and is developing implementation procedures for its water quality programs using the Aluminum Criteria Calculator. The calculator can be downloaded in either the excel format or R code and data format below. When procedures have been finalized, aluminum standard interpretation and application guidance will be linked below.