Current through Register Vol. 60, No. 12, December 1, 2021
pH (hydrogen ion concentration). pH
values may not fall outside the following ranges:
(a) Marine waters: 7.0-8.5;
(b) Estuarine and fresh waters (except
Cascade lakes): 6.5-8.5;
Cascade lakes above 3,000 feet altitude: pH values may not fall outside the
range of 6.0 to 8.5.
Total Dissolved Solids. Guide concentrations listed below may not be exceeded
unless otherwise specifically authorized by DEQ upon such conditions as it may
deem necessary to carry out the general intent of this plan and to protect the
beneficial uses set forth in OAR 340-04l-0320: 500.0 mg/l.
(3) Turbidity (Nephelometric Turbidity Units,
NTU). When appropriate studies are completed by the Corps of Engineers, or
others, the Environmental Quality Commission will, consistent with the
provisions of ORS Chapter 468, modify the turbidity standard, on a case-by-case
basis if necessary, to accommodate such specific water storage and development
projects in the South Umpqua Basin as are found to be in the best overall
interest of the public.
Design Criteria for Treatment and Control of Sewage Wastes:
During periods of low stream flows
(approximately May 1 to October 31):
stem Umpqua River, South Umpqua River, and all tributaries to the main stem and
South Umpqua Rivers: Treatment resulting in monthly average effluent
concentrations not to exceed 10 mg/l of BOD and 10 mg/l of SS or equivalent
(B) North Umpqua River
from mouth to Idleyld Park (river mile 0 to 35): Treatment resulting in monthly
average effluent concentrations not to exceed 10 mg/l of BOD and 10 mg/l of SS
or equivalent control;
Umpqua River above Idleyld Park (river mile 35) and all tributaries to North
Umpqua River: Treatment resulting in monthly average effluent concentrations
not to exceed 5 mg/l of BOD and 5 mg/l of SS or equivalent control.
(b) During the period of high
stream flows (approximately November 1 to April 30): A minimum of secondary
treatment or equivalent control and unless otherwise specifically authorized by
the Department, operation of all waste treatment and control facilities at
maximum practicable efficiency and effectiveness so as to minimize waste
discharges to public waters.