Current through Register Vol. 63, No. 3, March 1, 2024
(1)
(a) The
following values and implementation program must be applied to lakes,
reservoirs, estuaries and streams, except for ponds and reservoirs less than
ten acres in surface area, marshes and saline lakes:
(b) The following average Chlorophyll a
values must be used to identify water bodies where phytoplankton may impair the
recognized beneficial uses:
(A) Natural lakes
that thermally stratify: 0.01 mg/1;
(B) Natural lakes that do not thermally
stratify, reservoirs, rivers and estuaries: 0.015 mg/1;
(C) Average Chlorophyll a values may be based
on the following methodology (or other methods approved by the Department): A
minimum of three samples collected over any three consecutive months at a
minimum of one representative location (e.g., above the deepest point of a lake
or reservoir or at a point mid-flow of a river) from samples integrated from
the surface to a depth equal to twice the secchi depth or the bottom (the
lesser of the two depths); analytical and quality assurance methods must be in
accordance with the most recent edition of Standard Methods for the Examination
of Water and Wastewater.
(2) Upon determination by the Department that
the values in section (1) of this rule are exceeded, the Department may:
(a) In accordance with a schedule approved by
the Commission, conduct such studies as are necessary to describe present water
quality; determine the impacts on beneficial uses; determine the probable
causes of the exceedance and beneficial use impact; and develop a proposed
control strategy for attaining compliance where technically and economically
practicable. Proposed strategies could include standards for additional
pollutant parameters, pollutant discharge load limitations, and other such
provisions as may be appropriate. Where natural conditions are responsible for
exceedance of the values in section (1) of this rule or beneficial uses are not
impaired, the values in section (1) of this rule may be modified to an
appropriate value for that water body;
(b) Conduct necessary public hearings
preliminary to adoption of a control strategy, standards or modified values
after obtaining Commission authorization;
(c) Implement the strategy upon adoption by
the Commission.
(3) In
cases where waters exceed the values in section (1) of this rule and the
necessary studies are not completed, the Department may approve new activities
(which require Department approval), new or additional (above currently
approved permit limits) discharge loadings from point sources provided that it
is determined that beneficial uses would not be significantly impaired by the
new activity or discharge.
Stat. Auth.: ORS 468.020, 468B.030, 468B.035 &
468B.048
Stats. Implemented: ORS 468B.030, 468B.035 &
468B.048