Nacimiento Water Project – San Luis Obispo County Watershed Sanitary Survey Update 2015 Nacimiento Water Project Watershed Sanitary Survey Five Year Update ‐ 2015 Prepared By: San Luis Obispo County Department of Public Works Utilities Department Water Quality Laboratory Nacimiento Water Project – San Luis Obispo County Watershed Sanitary Survey Update 2015 Contents WATERSHED SANITARY SURVEY CHECKLIST ............................................................................... i ABBREVIATIONS ......................................................................................................................... ii 1 SUMMARY of INITIAL WATERSHED SANITARY SURVEY .................................................... 1 1.1 Recommendations from Initial Watershed Sanitary Survey ..................................... 2 1.2 Status of Recommendations ..................................................................................... 0 2 WATERSHED and WATER SUPPLY DELIVERY ..................................................................... 1 2.1 Reservoir Description ................................................................................................ 1 2.2 Watershed Security ................................................................................................... 1 2.3 Project Facilities ........................................................................................................ 2 2.4 Water Delivery Entitlement ...................................................................................... 5 2.5 Inspection and Surveillance of the Watershed ......................................................... 8 2.6 WATERSHED LAND USE ........................................................................................... 10 2.7 PESTICIDE and HERBICIDE USE ................................................................................ 13 3 Watershed Data Evaluation............................................................................................. 14 3.1 Water Quality – Limnology ..................................................................................... 14 3.2 Water Quality – Bacteriology .................................................................................. 16 3.2.1 Raw Water – Intake in Use .................................................................................. 16 3.2.2 Reservoir Intakes ................................................................................................ 17 3.2.3 Creeks and Tributaries ........................................................................................ 19 3.2.4 Raw Water Distribution ...................................................................................... 21 3.2.5 Surface Water Treatment Rule ........................................................................... 22 (Cryptosporidium and Giardia) ........................................................................................ 22 3.3 Water Quality – Nutrients ....................................................................................... 23 3.4 Algae ........................................................................................................................ 27 3.4.1 Drinking water limits ........................................................................................... 27 3.4.2 Algae Concerns ................................................................................................... 27 3.4.3 Monitoring conducted ........................................................................................ 28 3.5 Water Quality – Title 22 Metals .............................................................................. 30 3.5.1 Metals ................................................................................................................. 30 3.5.2 Trace Metals ....................................................................................................... 35 3.6 Water Quality – General Physical ........................................................................... 36 3.6.1 Odor .................................................................................................................... 36 i Nacimiento Water Project – San Luis Obispo County Watershed Sanitary Survey Update 2015 3.6.2 Turbidity .............................................................................................................. 40 3.6.3 Suspended Solids ................................................................................................ 40 3.6.4 General Mineral .................................................................................................. 41 3.6.5 Synthetic Organic Carbons and Volatile Organic Compounds ............................ 43 Water Quality Monitoring Programs ...................................................................... 44 3.7.1 San Luis Obispo County Flood Control and Water Conservation District ........... 44 4 Investigations and Future Projects .................................................................................. 48 4.1 Nacimiento Pipeline ‐ Water Infiltration Investigation ........................................... 48 4.1.1 Introduction ........................................................................................................ 48 4.1.2 Sampling .............................................................................................................. 48 4.1.3 Analytical Results ............................................................................................... 50 4.1.4 Additional Field Information ............................................................................... 53 4.1.5 Conclusion ........................................................................................................... 53 4.2 Interlake Tunnel Project .......................................................................................... 54 4.3 NEW STATEWIDE NPDES PERMIT ........................................................................... 57 5 CONCLUSIONS and RECOMMENDATIONS ...................................................................... 58 5.1 Conclusions ............................................................................................................. 58 5.2 2016 Recommendations ......................................................................................... 59 Water Quality – Future Water Quality Monitoring ............................................................. 59 6 REFERENCES .................................................................................................................... 60 ii Nacimiento Water Project – San Luis Obispo County Watershed Sanitary Survey Update 2015 Figures Figure 1: Nacimiento Water Project Overview ......................................................................... 4 Figure 2: Nacimiento Water Project Participants ..................................................................... 6 Figure 3: Nacimiento Reservoir Watershed and sub‐watersheds ............................................. 9 Figure 4: Nacimiento Reservoir Lower Watershed Land Use .................................................. 11 Figure 5: Nacimiento Reservoir Lower Watershed Pesticide and Herbicide Use .................... 13 Figure 6: Raw Water Total Coliform MPN .............................................................................. 16 Figure 7: Raw Water E. coli MPN ............................................................................................ 17 Figure 8: Nacimiento Reservoir Tributaries and Park Locations ............................................. 20 Figure 9: Raw Water Iron and Manganese ............................................................................. 31 Figure 10: Divers enter Nacimiento pipeline to videotape .................................................... 48 Figure 11: Pipeline water entering tank. Sample collection point at top of stairs. ............... 49 Figure 12: Location of river sample collection point .............................................................. 49 Figure 13: Piper diagram comparing river water, pipeline water and PR Sulfur Spring water ................................................................................................................................................. 51 Figure 14: Water samples collected from lake, river, and pipe on different days. ................ 52 Figure 15: Inside piece of micrometer exposed to pipeline water for six hours showing rust development ............................................................................................................................ 53 Figure 16: Proposed approximate tunnel alignment .............................................................. 54 Tables Table 1: Proposed Water Delivery Entitlement ........................................................................ 7 Table 2: Reservoir Intakes (Bacteriological Data) ................................................................... 18 Table 3: Watershed Tributaries (Bacteriological Data)........................................................... 19 Table 4: Raw Water Distribution (Bacteriological Data): ........................................................ 21 Table 5: Long Term 2 Enhanced Surface Treatment Rule Data (2014)................................... 22 Table 6: Long Term 2 Enhanced Surface Treatment Rule Data (2015 ‐ 2016) ....................... 22 Table 7: Nutrient Data Summary ............................................................................................