Westcas position paper SALINITY WATER QUALITY REGULATION Peggy W. Glass, Ph.D. February 28, 2019

Westcas position paper Managing dissolved salts is important, but there are practical limitations: Unavailability of practical treatment options in many cases. Insufficient science on aquatic life impacts Drought impacts on water supply

Westcas position paper Arid West Challenges: Natural geology and hydrology. Wide-spread use of home water softeners and de-icing salts. Effect of effluent discharge reductions due to permit limits, conservation, or reuse on water rights compliance. Limitations on trans-basin diversions and brackish water development as water supply alternatives.

Westcas position paper Recommendations: Water quality standards are not based on Total Dissolved Solids (TDS) except as needed to protect domestic water supply, livestock watering, or irrigation uses. Allow use of Iowa/Illinois approach for chloride and sulfate standards while updates to the approach are being developed. Recognize ephemeral and intermittent streams do not require rigorous aquatic life use standards. Provide that passing Whole Effluent Toxicity (WET) tests can demonstrate protection of aquatic life use.

Recommendations, cont’d: Westcas policy paper Recommendations, cont’d: Allow alternative standards or exemptions from standards during drought. Simplify process for using temporary standards. Allow consideration of Net Environmental Benefit. Establish Best Management Practices (BMP) rather than numeric limits when permit provisions are required.

Action Plan: Westcas policy paper Communicate with EPA on treatment challenges, need to base standards on use impacts and not historical quality, and need for interim solutions. Monitor development of treatment technology and research on relationships between dissolved salts and impacts on aquatic life. Coordinate with other organizations to develop short-term and long-term solutions.

Westcas actions to date Meetings held with EPA Headquarters, in conjunction with National Association of Clean Water Agencies (NACWA) to encourage further research on use-based criteria. Submitted comment letter on proposal by Fond du Lac Reservation in Minnesota to set conductivity criteria of 300 uS/cm as a daily maximum.

Modifications being discussed in texas Provide an option for using a flow other than design flow when assessing permit limits for Publicly Owned Treatment Works (POTWs). Consider passing WET tests as a demonstration of protection of aquatic life use. Establish BMPs rather than numeric limits when permit provisions are required. Use a flow statistic other than harmonic mean flow for instream flows when assessing permit limits.