This proposed rulemaking would revise the existing effluent limitations guidelines that apply to discharge of oil and gas extraction wastewater (called produced water) found at 40 CFR 435 Subpart E. The current rule at Subpart E allows for discharge of produced water west of the 98th meridian if it is of good enough quality and if it has a use in agriculture and wildlife propagation. The rulemaking would evaluate increased opportunities for discharge of treated produced water by expanding the geographic area where such discharges can occur and evaluate increased opportunities to discharge for other uses (such as critical minerals extraction and industrial cooling water).