Are facilities required to determine the quantities or concentrations of hazardous constituents released within a waste stream that is listed under CERCLA?

No. The determination of the exact quantities of hazardous substances released in a mixture, solution, or waste stream may be difficult; such a determination is not required by CERCLA. Potential releasers may choose instead, to report waste stream releases when the total amount of the waste stream released equals or exceeds the RQ listed for the waste stream constituent with the lowest RQ.