ABSTRACT
The normal model for standards is followed in Oregon where the standard is composed of designated beneficial uses and water quality criteria or action levels which are set to maintain these beneficial uses. The phased approach adopted accepts the possibility of detailed beneficial use surveys coupled with a use attainability study to provide compliance with the intent of the total maximum daily load (TMDL) process and possible revision of water quality standards. Water quality modeling estimates the effects that the various loadings have on the instream water quality and simulates the processes within the Columbia Slough. The TMDL process developed includes evaluation of alternatives for the most significant water quality problems found. Pursuing them now before definitive total maximum daily load are set concurs with the phased and iterative approach suggested by the TMDL setting process developed for the Columbia Slough.
