Clear lake Public water systems: WQ data & more

1. Clear lake Public water systems: WQ data & more May 17, 2019 for Blue Ribbon Committee – Technical Subcommittee by Amy Little, SWRCB – DDW – Mendocino District

2. introduction • Public Water System (PWS) is defined as “a system for the provision of water for human consumption through pipes or other constructed conveyances that has 15 or more service connections or regularly serves at least 25 individuals daily at least 60 days of the year.” (Section 116275 of CA Health & Safety Code) • 18 public water systems rely on Clear Lake as its source to supply treated water to approximately 38,000 people around the lake. • There are at least 18 intakes in different locations around the lake with different types of surface water treatment in place designed to meet state and federal requirements of the Safe Drinking Water Act.

3. Part 1: water quality data

4. Extensive water quality monitoring by PWS • Potentially useful water quality data is available to support assessments and more • Minimum monitoring required in source water for community PWS with more than 1,000 connections TYPICALLY includes: • Monthly bacteriological monitoring for total organic carbon, total coliform and E. coli • Annual: inorganics, nitrate, secondary standards (however, these are being moved to finish) • Triennial: nitrite, volatile organic chemicals, synthetic organic chemicals • Less frequent: radiological Note: Monitoring can vary tremendously (initial requirements, treatment dependent, and more) Secondary standards includes constituents related to the aesthetics of the water (e.g. iron)

5. GOAL Questions for tech sub-committee Create a dialogue with Blue Ribbon Committee Technical Subcommittee with newly compiled water quality information • Are you interested in these water quality parameters? • Is so, which ones? See Table 2 • How can we convey these parameters in a meaningful way?

6. Example wq parameter: pH

7. DIFFERENT WAYS TO PRESENT

8. Still more on ph

9. ND ND – Not Detected

11. Table 1. The median E. coli density, most probable number (MPN) was calculated for each arm of Clear Lake. A bold italicized value indicates that fewer than ten samples were collected.

12. Part 2: pws source water quality efforts

13. 2017 efforts to understand and improve source water quality by pws • In 2017, hired Corona Environmental Consultants to review and summarize all Lake plans/efforts to improve source water quality in Clear Lake, CA. [Plan Review | Plan Matrix]. • In this report, projects were prioritized by PWS (top three listed): • 1. Physical treatment (aeration and sonication) at the intake • 2. Nutrient Input and Cycling Study and Chemical Treatment • 3. Storm Water System Improvement Study To learn about these projects and key lessons learned, contact Tarrah Henrie of Corona • In 2018, two public water systems applied for DWSRF funding based on the outcome from the efforts above: Cal Water applied for a nutrient cycling project and Golden State Water applied for an aeration project.

14. Part 3: Mendocino complex impacts?

15. potential long term impacts to pws due to recent wildfires • During meeting in the Fall of 2018, David Cowan, Director of Lake County Water Resources Department, stated that approximately 60% of the county has burned in the last four years. • Dr. Amanda Hohner (WRF Report #4590) suggests in post-wildfire conditions that higher levels of natural organic matter in source water quality may lead to disinfection byproduct compliance issues. • We anticipate an increase in turbidity, nutrients, total organic carbon, and more [USGS info]

16. Average TOC (pre-2013): 4.1 mg/L Average TOC (post-2013): 5.4 mg/L

17. Significant recent increase in average HAA5 concentration, from 29.8 ug/L to 41.7 ug/L, ~40% increase. maximum contaminant level = 60 ug/L

18. Part 4: pws plan for emergencies

19. planning for emergencies • In May 2018, public water systems and our Division attended a Water Quality Failure Workshop, exploring potential emergency scenarios, including: • Cyanotoxins present in drinking water delivered to customers • Filters are unable to meet turbidity performance standards • Elevated manganese and ammonia concentration in source water (Fall 2017) • System-wide pressure loss (usually limited to a few customers) • Elevated disinfection byproducts in drinking water delivered to customers (future) This list was an exercise. There are additional efforts underway by PWS, including a mutual aid agreement.

20. How to support pws in clear lake?

21. How to support pws in clear lake?

23. Sources of information 2019 Clear Lake Public Water System Survey, State Water Resources Control Board – Division of Drinking Water – Water Quality Database, Corona Environmental Consulting reports, including 2018 Task 2 final report and Golden State Water Company: Clear Lake Watershed Sanitary Survey Update – Source Water Quality Improvement Grant Applications, Water Research Foundation Emerging DBPs Factsheet, Water Research Foundation Web Report #4590 Wildfire Impacts on Drinking Water Treatment Process Performance: Development of Evaluation Protocols and Management Practices, CA EPA Regional Water Quality Control Board – Central Valley Region Clear Lake Nutrient Total Maximum Daily Load Control Program 5-Year Update (2012), Effects of Wildfire on Drinking Water Utilities and Best Practices for Wildfire Risk Reduction and Mitigation, WRF & EPA, Web Report #4482 (2013), CALFIRE web-based statistical reports, Big Valley Band of Pomo Indians Clear Lake water quality dashboard and Clear Lake public water system permit reports.