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This position paper addresses the challenges of managing dissolved salts in water quality, provides recommendations for standards and exemptions, and outlines an action plan for coordination, communication, and research.
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Westcas position paper • Peggy W. Glass, Ph.D. • February 28, 2019 • SALINITY WATER QUALITY REGULATION
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.
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.
Westcas policy paper Action Plan: • 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.