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.
EPA published the new aluminum rule and
preamble in the federal register on March 19, 2021 (see below). The federal
criteria will become effective in Oregon for Clean Water Act purposes on April
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 was required to
establish new aluminum criteria in Oregon by Dec. 31, 2020.
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 values, 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 values 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.