Agenda packet — Arroyo Grande City Council, August 12, 2025 (part 5 of 5)

Total Dissolved
Solids Chloride Sodium Potassium Calcium Magnesium
Alkalinity,
Bicarbonate (as
CaCO3)
Sulfate Nitrite (as N) Total Kjeldahl
Nitrogen Boron Fluoride Iodide Manganese Bromide Alkalinity, Total (as CaCO3)
Alkalinity,
Carbonate (as
CaCO3)
Alkalinity,
Hydroxide (as
CaCO3)
Specific
Conductance Iron
Table A-2. NCMA Sentry Wells Water Quality Data
Well Date
32S/13E-31H09 7/30/2014 670 43 43 2.2 110 48 360 160 — < 1 < 0.1 0.15 < 0.01 0.029 < 0.1 360 < 10 < 10 1070 0.057 32S/13E-31H09 4/15/2014 680 42 43 3.3 87 43 340 170 — < 1 0.092 0.11 < 0.01 0.023 < 0.1 340 < 10 < 10 1070 0.05 32S/13E-31H09 1/16/2014 680 45 42 2.6 100 46 360 171 — < 1 < 0.05 0.13 < 0.01 0.032 < 0.1 360 < 10 < 10 1060 0.18 32S/13E-31H09 10/16/2013 670 40 44 2.6 100 47 350 180 — < 1 < 0.05 0.15 < 0.01 0.03 < 0.1 350 < 10 < 10 1053 0.11 32S/13E-31H09 7/10/2013 670 44 43 2.8 110 52 350 180 — < 1 0.072 0.12 < 0.01 0.032 < 0.1 350 < 10 < 10 1070 0.11 32S/13E-31H09 4/11/2013 720 43 40 2.7 98 46 350 170 — < 1 0.072 0.14 < 0.01 0.029 < 0.1 350 < 10 < 10 1070 0.12 32S/13E-31H09 1/16/2013 660 43 43 2.7 100 47 360 180 — < 1 0.07 0.1 < 0.01 0.031 < 0.1 360 < 10 < 10 1060 0.13 32S/13E-31H09 10/30/2012 660 40 44 2.9 110 49 345 170 — < 1 0.071 0.14 < 0.01 0.03 < 0.1 345 < 10 < 10 1070 0.086 32S/13E-31H09 7/24/2012 700 47 44 2.8 93 45 356 180 — < 1 < 0.1 0.17 < 0.01 0.029 < 0.1 356 < 10 < 10 1070 0.66 32S/13E-31H09 4/25/2012 680 48 44 2.7 95 43 350 200 — < 1 < 0.1 0.26 < 0.01 0.032 < 0.2 350 < 10 < 10 1070 0.2 32S/13E-31H09 1/10/2012 460 67 61 2 35 17 81 120 < 0.01 < 1 < 0.02 0.12 < 0.1 < 0.001 < 0.1 340 < 10 < 10 720 < 0.02 32S/13E-31H09 11/22/2011 690 41 39 2.7 100 46 350 160 — < 1 0.046 < 0.2 0.013 0.03 < 0.2 350 < 10 < 10 1010 0.029 32S/13E-31H09 7/25/2011 690 44 39 4.5 86 40 340 166.9 — < 1 < 0.1 0.145 < 0.01 0.026 < 0.1 340 < 5 < 5 1070 < 0.1 32S/13E-31H10 10/17/2024 467 47 49.3 3.31 38.4 50.5 229 100 ND ND 0.0732 J ND 0.273 B 0.15 229 ND ND 767 5.06 32S/13E-31H10 4/19/2024 696 37 48 B 3.52 117 53.8 328 180 0.020 J 0.64 0.0854 J 0.18 ND 0.178 ND 328 ND ND 1050 3.82 32S/13E-31H10 10/12/2023 710 34 39 3.1 110 51 330 160 < 0.039 < 0.41 0.074 J 0.22 0.019 0.17 0.14 330 < 3 < 3 1000 4.4 32S/13E-31H10 7/6/2023 790 34 40 3 97 52 360 170 — < 0.41 0.051 J 0.24 0.013 0.19 0.13 360 < 3 < 3 1000 5.9 32S/13E-31H10 4/13/2023 440 32 38 2.9 50 50 290 97 < 0.02 < 0.41 0.064 J 0.076 J 0.014 0.24 0.13 290 < 3 < 3 770 5.1 32S/13E-31H10 2/9/2023 410 31 36 3.3 39 51 270 82 < 0.099 < 0.41 0.055 J < 0.21 0.023 0.29 0.13 270 < 3 < 3 710 4.4 32S/13E-31H10 10/5/2022 660 34 38 2.7 110 58 350 160 < 0.01 0.12 J 0.048 J 0.18 0.0075 J 0.14 0.14 J 350 < 8.2 < 8.2 1020 4.7 32S/13E-31H10 7/12/2022 550 36 36 2.8 110 53 360 160 < 0.01 0.12 J 0.07 J 0.22 0.009 J 0.11 0.1 J 360 < 8.2 < 8.2 1060 4.2 32S/13E-31H10 4/7/2022 450 32 37 3.7 41 47 270 96 < 0.05 0.09 J 0.062 J 0.052 0.01 J 0.26 0.087 J 270 < 4.1 < 4.1 737 4.5 32S/13E-31H10 1/4/2022 690 33 35 2.6 100 48 360 170 < 0.05 < 0.2 0.059 J 0.18 0.009 J 0.12 0.11 J 360 < 8.2 < 8.2 1020 3.9 32S/13E-31H10 10/5/2021 630 34 36 2.7 110 52 360 160 < 0.05 0.21 0.067 J 0.21 0.0083 J 0.12 0.12 J 360 < 8.2 < 8.2 1020 4.5 32S/13E-31H10 7/14/2021 580 34 37 2.7 110 52 360 160 < 0.05 0.4 0.055 J 0.19 0.0086 J 0.15 0.13 J 360 < 8.2 < 8.2 1020 5.6 32S/13E-31H10 4/6/2021 480 36 41 3.1 31 52 250 93 < 0.01 0.17 J 0.062 J 0.055 0.011 J 0.18 0.16 J 250 < 4.1 < 4.1 — 2 32S/13E-31H10 1/6/2021 380 37 51 7.2 13 47 210 61 < 0.01 0.48 0.082 0.048 0.016 0.1 0.16 220 11 < 4.1 614 1.3 32S/13E-31H10 10/8/2020 660 33 35 2.6 97 47 350 150 < 0.01 0.23 0.079 J 0.18 0.0081 J 0.14 0.12 J 350 < 4.1 < 4.1 965 4.8 32S/13E-31H10 7/7/2020 510 42 51 5 27 48 220 99 < 0.01 0.1 J 0.084 J 0.052 0.022 J 0.17 0.2 220 < 4.1 < 4.1 720 1.9 32S/13E-31H10 4/21/2020 430 38 50 5.3 21 44 220 73 < 0.01 0.28 0.068 J 0.055 0.02 J 0.13 0.14 J 220 < 4.1 < 4.1 669 1.9 32S/13E-31H10 1/14/2020 520 36 42 3.7 80 51 310 130 < 0.01 0.11 J 0.077 J 0.16 0.014 J 0.2 0.092 J 310 < 4.1 < 4.1 843 4.4 32S/13E-31H10 10/14/2019 630 34 42 3.9 110 52 350 150 < 0.01 < 0.067 0.075 J 0.14 < 0.01 0.2 < 0.076 350 < 4.1 < 4.1 974 6.6 32S/13E-31H10 7/9/2019 890 44 50 3.4 110 57 320 200 < 0.01 0.24 0.092 J 0.18 0.026 J 0.21 0.19 J 320 < 8.2 < 8.2 1030 6 32S/13E-31H10 4/9/2019 630 43 48 3.4 100 50 320 200 < 0.01 0.17 J 0.099 J 0.21 0.015 J 0.18 0.15 J 320 < 8.2 < 8.2 1040 4.8 32S/13E-31H10 1/8/2019 620 35 41 3.3 100 54 340 160 < 0.01 0.17 J 0.081 J 0.18 0.012 J 0.16 0.14 340 < 4.1 < 4.1 973 5.6 32S/13E-31H10 10/9/2018 590 33 45 5.3 88 54 330 120 < 0.01 0.2 0.075 J 0.11 0.011 J 0.16 0.077 J 330 < 4.1 < 4.1 916 6.5 32S/13E-31H10 7/12/2018 510 34 46 6 45 54 300 96 0.013 J 0.23 0.08 J 0.12 0.012 J 0.12 0.16 300 < 4.1 < 4.1 846 3.8 32S/13E-31H10 4/10/2018 690 41 51 3.5 120 55 310 200 < 0.01 0.16 J 0.089 J 0.19 0.016 J 0.21 0.15 310 < 8.2 < 8.2 1020 4.7 32S/13E-31H10 1/10/2018 660 35 44 3.3 110 56 350 170 < 0.01 0.23 0.075 J 0.2 0.016 J 0.2 0.17 350 < 8.2 < 8.2 1020 5.3 32S/13E-31H10 10/10/2017 640 33 41 3.1 120 57 360 160 < 0.01 0.38 0.083 J 0.18 < 0.01 0.21 0.13 450 89 < 8.2 1070 4.3 32S/13E-31H10 7/11/2017 700 36 48 3.8 120 60 350 170 < 0.01 0.17 J 0.09 J 0.15 0.011 J 0.17 0.13 350 < 8.2 < 8.2 1020 4.7 32S/13E-31H10 4/12/2017 600 39 47 3.4 120 62 340 190 < 0.01 < 0.088 0.09 J 0.19 0.013 J 0.19 0.22 340 < 8.2 < 8.2 1020 5.2 32S/13E-31H10 1/13/2017 670 34 45 3.4 130 60 370 180 < 0.01 0.16 J 0.076 J 0.17 0.014 J 0.22 0.1 370 < 8.2 < 8.2 1020 7.8 32S/13E-31H10 10/12/2016 700 33 40 3.2 120 59 380 170 0.045 J 0.22 0.062 J 0.18 0.012 J 0.15 0.12 380 < 8.2 < 8.2 1040 5.3 32S/13E-31H10 7/20/2016 630 33 42 4.4 99 57 370 150 — 0.3 0.068 0.14 < 0.01 0.19 0.14 370 < 8.2 < 8.2 991 8.9 32S/13E-31H10 4/13/2016 670 37 46 3.4 120 57 350 180 — 0.21 0.078 0.19 0.011 0.23 0.14 350 < 8.2 < 8.2 1030 6.7 32S/13E-31H10 1/13/2016 380 37 49 9.9 6.8 46 170 54 — 0.43 0.044 0.088 0.014 0.084 0.19 210 34 < 4.1 603 2.2 32S/13E-31H10 10/14/2015 320 32 33 2.7 17 48 216 68 — < 1 0.089 0.12 0.016 0.098 < 0.1 227 11 < 10 600 1.4 32S/13E-31H10 7/15/2015 330 34 44 3.4 15 54 195 81 — < 1 0.082 < 0.1 < 0.01 0.081 < 0.1 213 18 < 10 610 0.98 32S/13E-31H10 4/16/2015 660 35 33 2.7 99 48 360 170 — < 1 0.083 0.163 < 0.01 0.17 < 0.1 360 < 10 < 10 1000 4.6 32S/13E-31H10 1/14/2015 760 55 56 3 110 50 300 250 — < 1 0.11 0.159 0.021 0.17 < 0.1 300 < 10 < 10 1070 4.2 32S/13E-31H10 10/16/2014 720 41 46 3.7 110 53 330 200 — < 1 0.1 < 0.1 < 0.01 0.17 < 0.1 330 < 10 < 10 1090 6.5 32S/13E-31H10 7/30/2014 660 34 35 2.4 95 49 420 160 — < 1 < 0.1 0.16 < 0.01 0.17 < 0.1 420 < 10 < 10 1040 6.5 32S/13E-31H10 4/17/2014 890 55 70 5.4 100 45 250 380 — < 1 0.15 0.12 0.01 0.31 0.13 250 < 10 < 10 1260 4.9 32S/13E-31H10 1/16/2014 900 57 66 4.6 110 50 240 360 — < 1 0.18 0.2 0.02 0.32 < 0.1 240 < 10 < 10 1260 6 32S/13E-31H10 10/16/2013 690 30 40 3.4 100 49 340 190 — < 1 0.091 0.14 < 0.01 0.23 < 0.1 340 < 10 < 10 1050 7.4

Page 11 of 17 ends

Total Dissolved
Solids Chloride Sodium Potassium Calcium Magnesium
Alkalinity,
Bicarbonate (as
CaCO3)
Sulfate Nitrite (as N) Total Kjeldahl
Nitrogen Boron Fluoride Iodide Manganese Bromide Alkalinity, Total (as CaCO3)
Alkalinity,
Carbonate (as
CaCO3)
Alkalinity,
Hydroxide (as
CaCO3)
Specific
Conductance Iron
Table A-2. NCMA Sentry Wells Water Quality Data
Well Date
32S/13E-31H10 7/11/2013 860 60 50 4.4 110 47 240 340 — < 1 0.18 0.15 0.02 0.28 < 0.1 240 < 10 < 10 1230 4.9 32S/13E-31H10 4/11/2013 900 60 69 4.6 110 47 250 350 — < 1 0.2 0.12 0.03 0.28 < 0.2 250 < 10 < 10 1250 5.7 32S/13E-31H10 1/16/2013 820 66 76 5 100 47 260 320 — < 1 0.21 0.13 < 0.01 0.31 < 0.2 260 < 10 < 10 1230 4.2 32S/13E-31H10 10/30/2012 780 65 75 4.7 100 46 255 280 — < 1 0.19 0.14 0.04 0.23 < 0.1 255 < 10 < 10 1190 4 32S/13E-31H10 7/25/2012 830 76 80 5.3 96 45 250 310 — < 1 0.22 0.15 0.04 0.24 < 0.1 250 < 10 < 10 1220 6.7 32S/13E-31H10 4/19/2012 790 87 69 4.5 52 37 250 270 — < 1 0.19 0.21 0.05 0.17 < 0.2 250 < 10 < 10 1180 4 32S/13E-31H10 1/12/2012 760 76 85 4 79 40 270 190 — < 1 0.23 0.21 0.069 0.23 < 0.2 270 < 10 < 10 1150 4.8 32S/13E-31H10 11/21/2011 720 39 38 3.4 96 43 320 180 — 3.5 0.079 0.19 0.013 0.17 < 0.1 320 < 10 < 10 1050 4.8 32S/13E-31H10 7/25/2011 760 69.3 66 6.4 80 35 310 208.8 — < 1 0.16 0.17 0.041 0.23 0.199 310 < 5 < 5 1170 5.3 32S/13E-31H10 1/24/2011 310 98 22 8.1 34 9.2 19 53 — < 1 < 0.1 0.2 4.42 0.4 0.63 19 < 2 < 2 480 10 32S/13E-31H10 10/28/2010 290 81 26 9.3 64 11 160 68 — < 1 < 0.1 0.2 ND 0.85 0.36 160 < 10 < 10 520 38 32S/13E-31H10 7/26/2010 438 85 34.3 1.93 61.7 30.4 30 210 — < 0.5 0.0435 0.58 0.22 1.46 0.32 30 < 1 < 1 690 35.5 32S/13E-31H10 4/26/2010 560 83 47.7 5.7 86.1 48.3 62 310 — 0.84 < 0.02 < 0.1 0.56 2.54 0.31 62 < 1 < 1 880 233 32S/13E-31H10 1/27/2010 460 130 45 25.4 682 124 112 100 — ND < 0.02 0.21 0.25 32.4 0.49 112 < 1 < 1 760 4360 32S/13E-31H10 10/20/2009 362 92 39.6 2.92 19.2 45.1 76.8 110 — < 0.5 0.0697 < 0.1 < 0.1 0.242 0.39 80 3.2 < 1 590 11.4 32S/13E-31H10 8/19/2009 420 160 48.4 3.37 49.9 20.4 17.6 54 — 1.1 ND < 0.1 0.25 1.76 0.68 17.6 < 1 < 1 690 242 32S/13E-31H10 5/16/1983 665 35 40 ND 85 65 360 90 — ND ND 0.2 ND 0.01 ND 360 ND ND 950 0.1 32S/13E-31H11 10/17/2024 710 41 45.5 3.32 117 53.9 316 190 N ND 0.0725 J 0.049 J ND 0.218 B 0.14 316 ND ND 1070 7.31 32S/13E-31H11 4/19/2024 722 53 53.6 3.64 120 53.3 351 180 0.033 J 0.814 0.0949 J 0.16 ND 0.312 0.15 351 ND ND 1120 6.48 32S/13E-31H11 10/12/2023 830 40 45 3.3 120 51 370 200 < 0.039 < 0.41 0.089 J 0.21 0.027 0.21 0.16 370 < 3 < 3 1100 6.7 32S/13E-31H11 7/6/2023 820 36 47 3.3 120 52 340 190 — < 0.41 0.067 J 0.21 0.02 0.21 0.15 340 < 3 < 3 1100 6.7 32S/13E-31H11 4/13/2023 440 36 42 3.2 46 50 260 130 < 0.02 < 0.41 0.055 J 0.064 J 0.018 0.3 0.14 260 < 3 < 3 820 7.3 32S/13E-31H11 2/9/2023 720 50 43 3.4 120 52 340 200 < 0.099 < 0.41 0.068 J < 0.21 0.027 0.19 0.14 340 < 3 < 3 1000 6 32S/13E-31H11 10/5/2022 700 36 44 3.2 120 55 340 200 < 0.01 0.092 J 0.06 J 0.17 0.0086 J 0.19 0.15 J 340 < 8.2 < 8.2 1060 5.5 32S/13E-31H11 7/12/2022 560 39 40 3 110 51 340 200 < 0.01 < 0.088 0.081 J 0.2 0.011 J 0.18 0.14 J 340 < 8.2 < 8.2 1100 5.4 32S/13E-31H11 4/7/2022 700 44 47 3.1 110 46 330 220 < 0.05 0.16 J 0.093 J 0.15 0.024 J 0.19 0.12 J 330 < 8.2 < 8.2 1060 4.8 32S/13E-31H11 1/4/2022 710 45 47 3.2 110 51 330 200 < 0.05 0.097 J 0.088 J 0.18 0.024 J 0.2 0.16 J 330 < 8.2 < 8.2 1070 5.6 32S/13E-31H11 10/5/2021 680 37 44 3.3 120 53 340 200 0.025 J 0.2 0.08 J 0.19 0.0089 J 0.23 0.12 J 340 < 8.2 < 8.2 1060 5.1 32S/13E-31H11 7/14/2021 640 37 41 3 110 50 350 210 < 0.05 0.13 J 0.06 J 0.19 0.012 J 0.22 0.15 J 350 < 8.2 < 8.2 1070 4.8 32S/13E-31H11 4/6/2021 680 37 42 3 110 49 340 210 < 0.01 0.15 J 0.072 J 0.2 0.011 J 0.2 0.15 J 340 < 8.2 < 8.2 — 4.6 32S/13E-31H11 1/6/2021 620 38 47 3.5 120 55 340 210 < 0.01 0.49 0.087 0.2 0.015 0.22 0.18 340 < 8.2 < 8.2 1050 4.9 32S/13E-31H11 10/8/2020 680 37 41 3.6 110 55 330 200 < 0.01 0.13 J 0.085 J 0.21 < 0.005 0.22 0.12 J 330 < 8.2 < 8.2 1020 11 32S/13E-31H11 7/7/2020 410 62 69 5.2 3.1 41 140 57 < 0.01 < 0.088 0.11 0.056 0.051 J 0.024 0.32 170 36 < 4.1 636 0.9 32S/13E-31H11 4/21/2020 450 60 59 4.4 5.1 45 170 85 < 0.01 0.21 0.099 J 0.068 0.054 J 0.044 0.26 180 14 < 4.1 698 0.73 32S/13E-31H11 1/14/2020 680 73 76 3.6 110 44 300 210 < 0.01 0.11 J 0.17 0.2 0.075 J 0.18 0.26 300 < 8.2 < 8.2 1070 3.8 32S/13E-31H11 10/14/2019 750 48 56 3.7 120 50 320 200 < 0.01 < 0.067 0.11 0.16 0.027 J 0.24 0.15 J 320 < 8.2 < 8.2 1070 5.7 32S/13E-31H11 7/9/2019 880 61 73 4 110 52 310 210 < 0.01 0.17 J 0.16 0.17 0.054 J 0.24 0.28 310 < 8.2 < 8.2 1110 5.9 32S/13E-31H11 4/9/2019 700 61 66 3.7 110 48 300 240 < 0.01 0.18 J 0.14 0.2 0.041 J 0.19 0.27 300 < 8.2 < 8.2 1140 3.7 32S/13E-31H11 1/8/2019 730 39 45 3.6 120 52 340 220 < 0.01 0.14 J 0.087 J 0.18 0.016 J 0.24 0.13 340 < 8.2 < 8.2 1090 8.2 32S/13E-31H11 10/9/2018 720 37 49 3.8 130 59 340 210 < 0.01 0.24 0.091 J 0.15 0.015 J 0.23 0.077 J 340 < 8.2 < 8.2 1090 8.2 32S/13E-31H11 7/12/2018 720 36 43 3.6 120 54 340 190 0.012 J 0.27 0.082 J 0.17 0.014 J 0.25 0.15 340 < 8.2 < 8.2 1110 7.2 32S/13E-31H11 4/10/2018 780 73 81 3.8 110 47 300 210 < 0.01 0.09 J 0.17 0.18 0.066 J 0.24 0.4 300 < 8.2 < 8.2 1130 7.3 32S/13E-31H11 1/10/2018 750 39 51 3.7 130 57 340 220 < 0.01 0.17 J 0.089 J 0.2 0.021 J 0.28 0.16 340 < 8.2 < 8.2 1090 5.9 32S/13E-31H11 10/10/2017 720 38 45 3.7 120 56 350 200 < 0.01 0.22 0.13 0.18 0.015 J 0.22 0.14 350 < 8.2 < 8.2 1080 5.6 32S/13E-31H11 7/11/2017 820 43 53 3.9 130 58 320 230 < 0.01 0.11 J 0.11 0.13 0.018 J 0.29 0.19 320 < 8.2 < 8.2 1110 9.7 32S/13E-31H11 4/12/2017 720 45 53 3.8 120 56 320 250 < 0.01 < 0.088 0.11 0.17 0.022 J 0.25 0.18 320 < 8.2 < 8.2 1100 6.3 32S/13E-31H11 1/13/2017 750 44 57 4 130 58 340 240 < 0.01 0.11 J 0.11 0.13 0.024 J 0.29 0.15 340 < 8.2 < 8.2 1100 7.2 32S/13E-31H11 10/12/2016 780 41 49 3.9 120 57 350 220 0.014 J 0.12 J 0.097 J 0.16 0.021 J 0.28 0.16 350 < 8.2 < 8.2 1100 8.1 32S/13E-31H11 7/20/2016 420 120 64 6.8 4.3 38 60 39 — 0.097 0.12 0.059 0.084 0.084 0.59 89 29 < 4.1 617 9 32S/13E-31H11 4/13/2016 410 110 64 604 3.9 40 51 56 — < 0.08 0.11 0.058 0.084 0.053 0.58 92 41 < 4.1 628 6.7 32S/13E-31H11 1/13/2016 450 120 70 7.7 4.5 36 49 65 — < 0.08 0.11 0.095 0.11 0.072 0.76 86 37 < 4.1 675 8.6 32S/13E-31H11 10/14/2015 350 110 69 9.2 3.7 31 42 74 — < 1 0.16 < 0.1 0.099 0.036 0.44 75 33 < 10 670 5.7 32S/13E-31H11 7/15/2015 380 120 85 11 4.3 35 40 85 — < 1 0.19 < 0.1 0.1 0.05 0.409 65 25 < 10 690 9.6 32S/13E-31H11 4/16/2015 400 120 66 7.6 4.9 36 54 100 — < 1 0.17 < 0.1 0.088 0.039 0.481 76 22 < 10 700 6.6 32S/13E-31H11 1/14/2015 420 125 68 7 6.4 37 45 126 — < 1 0.15 < 0.1 0.097 0.038 0.385 65 20 < 10 720 3.5 32S/13E-31H11 10/16/2014 370 120 78 13 4.2 29 53 77 — < 1 0.17 < 0.1 0.11 0.04 0.35 88 < 10 < 10 740 4.5

Page 12 of 17 ends

Total Dissolved
Solids Chloride Sodium Potassium Calcium Magnesium
Alkalinity,
Bicarbonate (as
CaCO3)
Sulfate Nitrite (as N) Total Kjeldahl
Nitrogen Boron Fluoride Iodide Manganese Bromide Alkalinity, Total (as CaCO3)
Alkalinity,
Carbonate (as
CaCO3)
Alkalinity,
Hydroxide (as
CaCO3)
Specific
Conductance Iron
Table A-2. NCMA Sentry Wells Water Quality Data
Well Date
32S/13E-31H11 7/30/2014 450 120 71 4.4 9.6 43 53 130 — < 1 0.15 0.12 0.1 0.078 0.29 73 20 < 10 800 8 32S/13E-31H11 4/17/2014 370 120 89 14 2.4 17 76 39 — < 1 0.16 < 0.1 0.12 0.03 0.43 121 45 < 10 720 3.7 32S/13E-31H11 1/16/2014 350 122 89 15 2 18 67.5 42 — < 1 0.17 0.1 0.09 0.026 0.48 125 57.5 < 10 710 2.3 32S/13E-31H11 10/16/2013 360 100 98 20 3.1 15 66 36 — < 1 0.19 < 0.1 0.11 0.057 0.38 139 73 < 10 710 4.1 32S/13E-31H11 7/11/2013 370 140 70 6.3 4 23 82 40 — < 1 0.2 0.11 0.11 0.043 0.44 117 35 < 10 730 3.2 32S/13E-31H11 4/11/2013 340 90 81 14 2.9 18 77.5 30 — < 1 0.19 0.12 0.07 0.046 0.3 155 77.5 < 10 650 3.2 32S/13E-31H11 1/16/2013 360 107 99 7.1 3.3 24 110 36 — < 1 0.25 < 0.1 < 0.01 0.048 0.4 165 55 < 10 720 3.7 32S/13E-31H11 10/30/2012 380 97 100 6.4 4.5 24 130 38 — < 1 0.28 < 0.1 0.1 0.09 0.2 168 38 < 10 720 6.1 32S/13E-31H11 7/25/2012 240 49 56 11 5.4 22 99 43 — < 1 0.16 0.19 0.023 0.11 < 0.1 132 33 < 10 470 6.6 32S/13E-31H11 4/19/2012 380 100 87 5.5 3.5 26 150 79 — < 1 0.27 0.26 0.09 0.033 0.68 180 30 < 10 750 1.6 32S/13E-31H11 1/12/2012 480 96 110 4.9 5.6 33 154 95 — < 1 0.28 < 0.2 0.11 0.01 0.306 180 26 < 10 850 0.19 32S/13E-31H11 11/21/2011 390 90 78 4.6 5.2 24 111 86 — < 1 0.19 0.13 0.092 0.014 0.28 128 17 < 10 720 0.5 32S/13E-31H11 7/25/2011 260 29.3 23 5.3 8.7 20 84 80 — < 1 < 0.1 0.199 0.072 0.041 < 0.1 89 < 5 < 5 440 2.7 32S/13E-31H11 4/21/2011 580 118 70 19 49 17 8.8 274 — < 1 < 0.1 0.29 0.109 0.091 0.4 11.3 2.5 < 2 950 ND 32S/13E-31H11 1/24/2011 680 110 60 17 64 22 5 330 — < 1 < 0.1 0.22 0.96 0.16 0.31 11.2 6.2 < 2 1040 10 32S/13E-31H11 10/21/2010 770 100 68 12 88 31 14 380 — < 1 < 0.1 0.28 ND 0.054 < 0.3 14 < 10 < 10 1163 2.2 32S/13E-31H11 7/26/2010 783 130 80.1 8.58 142 42 2.8 450 — < 0.5 < 0.02 0.26 0.31 3.97 0.77 2.8 < 1 < 1 1200 593 32S/13E-31H11 4/26/2010 1130 160 70.2 6.48 208 50.7 8.4 530 — 0.56 < 0.02 0.23 0.54 3.1 0.97 8.4 < 1 < 1 1600 383 32S/13E-31H11 1/27/2010 1740 430 55.6 4.98 282 43 < 1 680 — < 0.5 0.0819 0.14 0.41 9.41 2 < 1 < 1 < 1 2300 170 32S/13E-31H11 10/20/2009 2250 1000 19.5 2.4 487 22.5 5 410 — 0.98 0.0532 0.13 < 0.1 13.1 4.5 5 < 1 < 1 3100 236 32S/13E-31H11 8/19/2009 322 150 93.2 16.7 23.9 12.1 3 4 — 1.3 ND 0.19 0.5 0.71 0.74 23 20 < 1 640 153 32S/13E-31H11 5/16/1983 840 80 90 ND 100 50 250 160 — ND ND 0.2 ND 0.14 ND 250 ND ND 1200 0.1 32S/13E-31H12 4/21/2011 410 97 100 7.2 3.5 21 80 134 — < 1 0.23 0.18 0.097 0.065 0.42 100 20 < 2 770 ND 32S/13E-31H12 1/24/2011 440 92 90 9.2 3.4 27 90 140 — < 1 0.25 0.11 0.94 0.041 0.35 110 20 < 2 810 2.2 32S/13E-31H12 10/21/2010 460 90 110 15 6.8 32 94 140 — < 1 0.2 0.1 ND 0.1 0.38 124 30 < 10 868 3.5 32S/13E-31H12 7/26/2010 478 83 109 5.94 52.9 30.4 122 94 — < 0.5 0.255 < 0.1 0.41 0.477 0.56 130 8 < 1 730 61 32S/13E-31H12 4/26/2010 452 83 83 7.42 29.3 34.5 72 190 — 0.56 0.134 < 0.1 0.65 0.702 0.4 86 14 < 1 810 71 32S/13E-31H12 1/27/2010 496 71 92.2 10.6 22.9 39.1 13 230 — < 0.5 0.323 < 0.1 0.2 0.604 0.29 51 38 < 1 780 54.4 32S/13E-31H12 10/20/2009 564 71 80.8 8.63 33.2 49.8 49.6 310 — < 0.5 0.148 < 0.1 < 0.1 0.337 0.32 64 14.4 < 1 850 20 32S/13E-31H12 8/19/2009 522 180 148 71.6 95.2 8.42 30 3.5 — 1.7 ND 0.24 0.52 2.36 0.76 170 140 < 1 1000 278 32S/13E-31H12 5/16/1983 630 40 40 ND 90 50 330 80 — ND ND 0.1 ND 0.02 ND 330 ND ND 900 0.05 32S/13E-31H13 2/16/2022 710 40 42 3.1 110 48 340 220 < 0.05 0.17 J 0.077 J 0.19 — 0.2 0.2 340 < 8.2 < 8.2 1080 4.1 32S/13E-31H13 1/4/2022 730 39 42 3 110 50 350 200 < 0.05 < 0.2 0.081 J 0.18 0.014 J 0.17 0.14 J 350 < 8.2 < 8.2 1060 3.9 32S/13E-31H13 10/5/2021 500 100 83 3.8 11 43 200 41 < 0.05 0.11 J 0.17 0.067 0.051 J 0.22 0.33 210 8.4 < 4.1 772 0.5 32S/13E-31H13 7/14/2021 490 99 85 3.6 13 35 210 29 < 0.05 < 0.2 0.16 0.059 0.049 J 0.13 0.34 220 9 < 4.1 760 0.76 32S/13E-31H13 4/6/2021 430 110 97 4.2 2.9 28 170 0.52 J < 0.01 < 0.088 0.19 0.066 0.056 J 0.061 0.36 210 38 < 4.1 — 0.16 32S/13E-31H13 1/6/2021 480 110 98 4.4 3 28 170 0.48 < 0.01 0.3 0.21 0.054 0.063 0.063 0.35 210 33 < 4.1 678 0.18 32S/13E-31H13 10/8/2020 530 100 98 4.3 3.8 31 180 0.45 J < 0.01 < 0.088 0.22 0.063 0.059 J 0.074 0.32 210 32 < 4.1 685 0.94 32S/13E-31H13 7/7/2020 500 110 100 4.4 3.2 29 180 2.1 < 0.01 < 0.088 0.21 0.054 0.069 J 0.052 0.35 200 25 < 4.1 729 0.2 32S/13E-31H13 4/21/2020 470 100 100 4.8 2.6 30 180 0.4 J < 0.01 0.076 J 0.2 0.064 0.079 J 0.048 0.36 220 37 < 4.1 721 0.43 32S/13E-31H13 1/14/2020 430 120 110 4.6 3.3 29 190 9.5 < 0.01 < 0.067 0.25 0.084 0.094 J 0.054 0.28 220 35 < 4.1 730 0.44 32S/13E-31H13 10/14/2019 280 99 93 4.7 2.7 32 180 0.58 J < 0.01 < 0.067 0.18 0.064 0.066 J 0.054 0.3 210 37 < 4.1 675 0.34 32S/13E-31H13 7/9/2019 500 90 83 4.7 3.7 36 170 0.56 J < 0.01 0.079 J 0.16 0.062 0.059 J 0.078 0.35 200 26 < 4.1 654 2.9 32S/13E-31H13 4/9/2019 460 100 79 4 3.8 34 180 7.5 < 0.01 0.052 J 0.18 0.075 0.055 J 0.069 0.31 210 27 < 4.1 690 2.1 32S/13E-31H13 1/8/2019 400 99 79 4.3 6.7 42 180 19 < 0.01 0.06 J 0.17 0.057 0.057 J 0.13 0.29 200 19 < 4.1 703 2.2 32S/13E-31H13 10/9/2018 400 84 79 4.2 4.9 43 190 13 < 0.01 0.052 J 0.16 0.043 J 0.045 J 0.083 0.18 220 23 < 4.1 678 2.1 32S/13E-31H13 7/12/2018 470 81 72 3.9 3.9 38 190 13 0.012 J 0.096 J 0.14 0.041 J 0.045 J 0.064 0.31 220 25 < 4.1 699 0.86 32S/13E-31H13 4/10/2018 490 82 78 3.8 4.5 44 190 20 < 0.01 < 0.084 0.14 0.039 J 0.041 J 0.083 0.3 220 30 < 4.1 676 4.2 32S/13E-31H13 1/10/2018 430 75 75 3.8 4.3 38 190 7.2 < 0.01 < 0.084 0.14 0.05 0.046 J 0.07 0.25 210 26 < 4.1 626 2.5 32S/13E-31H13 10/10/2017 390 77 70 3.7 4.9 38 190 15 < 0.01 0.11 J 0.16 0.034 J 0.039 J 0.079 0.28 220 29 < 4.1 648 1.1 32S/13E-31H13 7/11/2017 390 76 80 3.9 7.8 45 190 30 < 0.01 < 0.088 0.15 0.033 J 0.036 J 0.13 0.28 210 19 < 4.1 680 2.2 32S/13E-31H13 4/12/2017 430 79 87 4.4 4 44 180 21 < 0.01 0.13 J 0.17 0.024 J 0.043 J 0.077 0.28 220 40 < 4.1 667 4.5 32S/13E-31H13 1/13/2017 480 81 95 4.7 3.9 41 190 14 < 0.01 < 0.088 0.19 0.037 J 0.056 J 0.065 0.31 220 33 < 4.1 652 3.3 32S/13E-31H13 10/12/2016 410 80 87 4.3 4.2 43 190 22 0.015 J < 0.088 0.18 0.04 J 0.055 J 0.072 0.29 220 33 < 4.1 678 2.3 32S/13E-31H13 7/20/2016 510 91 99 5.1 2.4 34 170 19 — < 0.08 0.22 0.043 0.054 0.038 0.43 210 44 < 4.1 694 1.2 32S/13E-31H13 4/13/2016 450 94 99 4.6 2.5 33 150 25 — < 0.08 0.22 0.054 0.045 0.035 0.44 200 51 < 4.1 701 1.2

Page 13 of 17 ends

Total Dissolved
Solids Chloride Sodium Potassium Calcium Magnesium
Alkalinity,
Bicarbonate (as
CaCO3)
Sulfate Nitrite (as N) Total Kjeldahl
Nitrogen Boron Fluoride Iodide Manganese Bromide Alkalinity, Total (as CaCO3)
Alkalinity,
Carbonate (as
CaCO3)
Alkalinity,
Hydroxide (as
CaCO3)
Specific
Conductance Iron
Table A-2. NCMA Sentry Wells Water Quality Data
Well Date
32S/13E-31H13 1/13/2016 460 99 97 4.8 2.6 32 150 30 — < 0.08 0.19 0.084 < 0.01 0.038 0.53 190 43 < 4.1 717 0.33 32S/13E-31H13 10/14/2015 370 85 91 4.8 3.1 32 159 45 — < 1 0.23 < 0.1 0.06 0.043 0.26 189 30 < 10 710 0.3 32S/13E-31H13 7/15/2015 390 90 99 4.4 2.7 34 145 55 — < 1 0.21 < 0.1 0.06 0.034 0.24 185 40 < 10 730 0.24 32S/13E-31H13 4/16/2015 360 89 86 4.8 2.6 31 137 58 — < 1 0.2 < 0.1 0.057 0.03 0.266 172 35 < 10 680 0.42 32S/13E-31H13 1/14/2015 390 90 84 4.8 2 31 140 61 — < 1 0.18 < 0.1 0.059 0.035 0.235 170 30 < 10 670 0.47 32S/13E-31H13 10/16/2014 370 80 84 5 3.2 32 146 59 — < 1 0.19 < 0.1 0.055 0.044 0.18 170 24 < 10 720 0.61 32S/13E-31H13 7/30/2014 380 86 81 4.2 3.6 35 158 61 — < 1 0.16 < 0.1 0.05 0.047 0.17 175 17 < 10 730 0.25 32S/13E-31H13 4/17/2014 380 84 86 5.2 3 26 120 87 — < 1 0.18 < 0.1 0.08 0.032 0.3 143 23 < 10 730 0.45 32S/13E-31H13 1/16/2014 390 89 91 5 4.1 34 119 103 — < 1 0.2 < 0.1 0.06 0.043 0.34 136 17 < 10 740 0.3 32S/13E-31H13 10/16/2013 410 84 87 4.7 5.3 33 114 130 — < 1 0.17 < 0.1 0.08 0.053 0.3 124 10 < 10 760 0.28 32S/13E-31H13 7/11/2013 420 80 70 4.8 4.5 35 116 120 — < 1 0.19 < 0.1 0.06 0.047 0.21 136 20 < 10 760 0.19 32S/13E-31H13 4/11/2013 450 77 77 4.7 5.8 38 113 150 — < 1 0.19 < 0.1 0.06 0.069 0.2 128 15 < 10 780 0.15 32S/13E-31H13 1/15/2013 420 74 78 4.7 7 40 110 180 — < 1 0.18 < 0.1 < 0.01 0.087 < 0.1 125 15 < 10 810 0.55 32S/13E-31H13 10/30/2012 380 88 99 5.7 3.3 30 160 63 — < 1 0.25 < 0.1 0.08 0.035 0.3 168 7.5 < 10 740 0.33 32S/13E-31H13 7/25/2012 390 108 107 5.5 2.7 29 13 66 — < 1 0.28 < 0.1 0.079 0.0037 0.23 168 155 < 10 750 0.84 32S/13E-31H13 4/19/2012 390 110 83 4.3 2.5 26 400 68 — < 1 0.22 0.23 0.09 0.032 0.39 420 20 < 10 790 0.24 32S/13E-31H13 1/12/2012 410 94 95 4.5 3 28 300 68 — < 1 0.24 < 0.2 0.1 0.032 0.31 320 20 < 10 760 0.89 32S/13E-31H13 11/21/2011 410 94 83 4.6 3.4 30 152 72 — < 1 0.21 < 0.1 0.09 0.035 0.3 160 8 < 10 730 0.65 32S/13E-31H13 7/25/2011 420 89.7 84 7.1 4.4 31 147.5 91.8 — < 1 0.2 < 0.1 0.071 0.046 0.297 150 2.5 < 5 760 1.9 32S/13E-31H13 4/21/2011 380 88 110 6.3 4 27 140 101 — < 1 0.41 0.14 0.07 0.13 0.33 140 < 2 < 2 750 ND 32S/13E-31H13 1/24/2011 430 83 73 6 6.3 31 160 100 — < 1 0.22 0.11 0.66 0.078 0.28 160 < 2 < 2 780 0.49 32S/13E-31H13 10/21/2010 410 87 100 3.9 6 33 148 100 — < 1 0.14 < 0.1 ND 0.087 < 0.3 148 < 10 < 10 796 0.66 32S/13E-31H13 7/26/2010 446 94 93 8.81 10.2 32 38.4 120 — < 0.5 0.142 < 0.1 0.32 0.196 0.48 56 17.6 < 1 700 22.4 32S/13E-31H13 4/26/2010 416 96 87.6 9.86 14.8 37.1 46 150 — 0.63 0.132 < 0.1 0.39 0.579 0.44 58 12 < 1 780 56.2 32S/13E-31H13 1/27/2010 498 89 79.6 10.2 15.6 38 31 180 — 0.56 0.132 < 0.1 0.19 0.283 0.38 51 20 < 1 810 23.6 32S/13E-31H13 10/20/2009 446 100 97.1 12.8 16.4 37.9 26.6 180 — 0.56 0.168 0.15 < 0.1 0.18 0.42 42.6 16 < 1 760 18.9 32S/13E-31H13 8/19/2009 426 160 101 18.9 93.2 29.1 64.4 36 — 0.98 ND 0.16 0.31 5.49 0.6 84.4 20 < 1 790 682 32S/13E-31H13 5/16/1983 770 60 70 ND 90 70 330 120 — ND ND 0.1 ND 0.02 ND 330 ND ND 1100 0.24 12N/36W-36L01 10/16/2024 907 37 67.2 3.63 130 45.7 169 400 0.44 H H3 ND 0.159 J N ND ND 0.070 J 169 ND ND 1180 ND 12N/36W-36L01 4/18/2024 883 36 68.7 B 3.59 130 45.9 170 410 0.47 0.854 0.166 J 0.047 J ND ND 0.070 J 170 ND ND 1180 ND 12N/36W-36L01 10/12/2023 920 38 64 3.7 130 44 190 410 < 0.02 < 0.41 0.17 0.051 J 0.0021 < 0.0045 0.096 190 < 3 < 3 1200 < 0.014 12N/36W-36L01 7/6/2023 1000 39 70 3.7 140 45 180 420 — < 0.41 0.13 0.084 J < 0.00045 < 0.0045 0.098 180 < 3 < 3 1200 < 0.014 12N/36W-36L01 4/13/2023 880 38 68 3.4 120 43 190 410 < 0.02 < 0.41 0.14 0.079 J ND < 0.0045 0.097 190 < 3 < 3 1200 < 0.014 12N/36W-36L01 2/9/2023 860 38 65 3.4 130 45 190 410 < 0.02 < 0.41 0.15 0.08 J 0.001 < 0.0045 0.095 190 < 3 < 3 1200 < 0.014 12N/36W-36L01 10/5/2022 880 39 68 3.4 130 47 180 440 < 0.01 < 0.088 0.15 0.032 J < 0.005 < 0.004 0.099 J 180 < 8.2 < 8.2 1200 < 0.03 12N/36W-36L01 7/12/2022 920 37 66 3.3 130 45 180 430 < 0.01 < 0.088 0.18 0.054 J < 0.005 < 0.004 < 0.14 180 < 8.2 < 8.2 1210 < 0.03 12N/36W-36L01 4/6/2022 840 37 64 3.3 130 43 180 400 < 0.05 0.15 J 0.15 0.033 J < 0.1 < 0.01 < 0.2 180 < 8.2 < 8.2 1190 < 0.05 12N/36W-36L01 1/6/2022 810 38 62 3.3 120 42 180 420 < 0.05 0.29 0.15 0.044 J < 0.1 < 0.01 0.085 J 180 < 8.2 < 8.2 1190 0.031 J 12N/36W-36L01 10/6/2021 890 33 67 3.3 130 44 180 400 < 0.05 < 0.2 0.15 < 0.1 < 0.1 < 0.01 < 0.4 180 < 8.2 < 8.2 — < 0.05 12N/36W-36L01 7/15/2021 840 34 63 3.3 120 43 180 420 < 0.05 < 0.2 0.17 < 0.1 < 0.1 < 0.01 < 0.4 180 < 8.2 < 8.2 1180 < 0.05 12N/36W-36L01 4/8/2021 840 38 67 3.4 130 44 180 420 < 0.01 0.19 J 0.16 0.047 J < 0.005 < 0.004 < 0.07 180 < 8.2 < 8.2 1170 < 0.03 12N/36W-36L01 1/7/2021 820 39 69 3.3 130 47 180 430 < 0.01 0.48 0.16 0.053 < 0.005 < 0.004 0.17 180 < 8.2 < 8.2 1170 < 0.03 12N/36W-36L01 10/11/2020 940 39 67 3.3 130 44 180 440 < 0.01 0.14 J 0.16 0.046 J < 0.005 0.004 J 0.1 J 180 < 8.2 < 8.2 1180 0.08 12N/36W-36L01 7/8/2020 1000 40 71 3.5 130 46 180 430 < 0.01 < 0.088 0.17 0.051 < 0.01 < 0.004 0.13 J 180 < 8.2 < 8.2 1190 < 0.03 12N/36W-36L01 4/22/2020 880 38 65 3.3 120 42 180 420 < 0.01 0.14 J 0.16 0.034 J < 0.01 < 0.004 0.08 J 180 < 8.2 < 8.2 1210 0.055 12N/36W-36L01 1/15/2020 960 39 70 3.6 140 45 180 420 < 0.01 0.13 J 0.18 0.056 < 0.01 < 4 0.092 J 180 < 8.2 < 8.2 1140 0.1 12N/36W-36L01 10/15/2019 880 38 73 3.6 140 45 180 440 < 0.01 0.093 J 0.18 0.044 J < 0.01 < 4 0.12 J 180 < 8.2 < 8.2 1190 0.078 12N/36W-36L01 7/10/2019 1100 37 70 3.6 140 51 180 430 < 0.01 0.15 J 0.17 0.047 J < 0.01 < 0.004 < 0.076 180 < 8.2 < 8.2 1180 < 0.03 12N/36W-36L01 4/10/2019 870 39 64 3.5 130 48 180 440 < 0.01 1.5 0.16 0.056 < 0.01 < 0.004 0.14 J 180 < 8.2 < 8.2 1190 0.078 12N/36W-36L01 1/9/2019 840 39 70 3.4 140 46 180 420 0.022 J 0.23 0.17 0.064 < 0.01 < 0.004 0.089 J 180 < 8.2 < 8.2 1200 < 0.03 12N/36W-36L01 10/10/2018 850 38 67 3.5 140 49 180 430 < 0.01 0.16 J 0.16 0.026 J < 0.01 < 0.004 < 0.058 180 < 8.2 < 8.2 1190 0.19 12N/36W-36L01 7/10/2018 960 39 64 3.4 130 47 180 430 < 0.01 0.11 J 0.17 0.12 < 0.01 < 0.004 0.063 J 180 < 8.2 < 8.2 1230 < 0.03 12N/36W-36L01 4/11/2018 900 39 70 3.5 140 49 180 430 < 0.01 0.11 J 0.16 0.052 < 0.01 < 0.004 0.1 180 < 8.2 < 8.2 1190 < 0.03 12N/36W-36L01 1/11/2018 940 38 76 3.5 140 50 180 440 < 0.01 0.19 J 0.17 0.073 < 0.01 < 0.004 0.097 J 180 < 8.2 < 8.2 1180 < 0.03 12N/36W-36L01 10/11/2017 880 35 65 3.7 140 50 190 430 < 0.01 0.14 J 0.19 0.048 J < 0.01 0.0054 J < 0.12 190 < 8.2 < 8.2 1210 0.23 12N/36W-36L01 7/12/2017 1000 37 73 3.9 150 55 180 420 < 0.01 0.15 J 0.17 0.034 J < 0.01 0.0048 J < 0.058 180 < 8.2 < 8.2 1180 0.23

Page 14 of 17 ends

Total Dissolved
Solids Chloride Sodium Potassium Calcium Magnesium
Alkalinity,
Bicarbonate (as
CaCO3)
Sulfate Nitrite (as N) Total Kjeldahl
Nitrogen Boron Fluoride Iodide Manganese Bromide Alkalinity, Total (as CaCO3)
Alkalinity,
Carbonate (as
CaCO3)
Alkalinity,
Hydroxide (as
CaCO3)
Specific
Conductance Iron
Table A-2. NCMA Sentry Wells Water Quality Data
Well Date
12N/36W-36L01 4/12/2017 860 37 73 4 130 49 180 420 < 0.01 0.14 J 0.17 0.017 J < 0.01 0.0087 J 0.062 J 180 < 8.2 < 8.2 1170 0.43 12N/36W-36L01 1/12/2017 870 38 76 3.8 150 55 190 430 < 0.01 0.12 J 0.21 0.036 J < 0.01 < 0.004 0.07 J 190 < 8.2 < 8.2 1180 0.11 12N/36W-36L01 10/12/2016 890 35 72 3.8 140 56 190 430 0.019 J 0.11 J 0.17 0.036 J < 0.01 < 0.004 0.12 J 190 < 8.2 < 8.2 1220 0.037 J 12N/36W-36L01 7/19/2016 920 37 69 3.6 130 50 180 430 — 0.25 0.15 0.043 < 0.01 < 0.004 0.1 180 < 8.2 < 8.2 1200 < 0.03 12N/36W-36L01 4/12/2016 860 38 65 3.5 130 49 180 390 — < 0.08 0.16 0.036 < 0.01 < 0.004 0.12 180 < 8.2 < 8.2 1210 < 0.05 12N/36W-36L01 1/14/2016 890 36 64 3.4 130 49 180 410 — < 0.08 0.15 0.062 < 0.01 < 0.004 0.1 180 < 8.2 < 8.2 1210 0.07 12N/36W-36L01 10/15/2015 920 37 63 4.2 120 47 180 400 — < 1 0.15 < 0.2 < 0.01 < 0.005 < 0.2 180 < 10 < 10 1210 < 0.05 12N/36W-36L01 7/16/2015 930 39 74 2.8 140 50 180 410 — < 1 0.15 < 0.1 < 0.01 < 0.005 < 0.1 180 < 10 < 10 1210 < 0.05 12N/36W-36L01 4/14/2015 890 38 55 3.1 110 44 180 440 — 1 0.16 < 0.2 < 0.01 < 0.005 < 0.2 180 < 10 < 10 1160 < 0.05 12N/36W-36L01 1/13/2015 880 39 59 3 120 45 180 440 — < 1 0.14 < 0.1 < 0.01 < 0.005 < 0.1 180 < 10 < 10 1160 < 0.05 12N/36W-36L01 10/15/2014 910 34 58 3.7 120 43 180 380 — < 1 0.14 < 0.2 < 0.01 < 0.005 < 0.2 180 < 10 < 10 1210 < 0.05 12N/36W-36L01 7/30/2014 890 36 61 3.2 120 47 180 390 — < 1 0.12 < 0.2 < 0.01 < 0.005 < 0.2 180 < 10 < 10 1220 < 0.05 12N/36W-36L01 4/16/2014 910 36 46 2.6 76 27 180 440 — < 1 0.15 < 0.1 < 0.01 < 0.005 < 0.1 180 < 10 < 10 1200 < 0.05 12N/36W-36L01 1/16/2014 910 35 60 3.1 110 42 180 416 — 1.1 0.14 < 0.2 < 0.01 < 0.005 < 0.2 180 < 10 < 10 1190 < 0.05 12N/36W-36L01 10/16/2013 910 40 63 4.5 120 43 170 460 — < 1 0.13 < 0.2 < 0.01 < 0.005 < 0.2 170 < 10 < 10 1210 < 0.05 12N/36W-36L01 7/10/2013 910 39 54 3.2 120 42 175 430 — < 1 0.14 < 0.1 < 0.01 < 0.005 < 0.1 175 < 10 < 10 1210 0.18 12N/36W-36L01 4/11/2013 890 38 59 3.6 110 43 180 420 — < 1 0.16 < 0.2 < 0.01 < 0.005 < 0.2 180 < 10 < 10 1200 < 0.05 12N/36W-36L01 1/15/2013 870 39 61 3.4 110 41 178 440 — < 1 0.15 < 0.2 < 0.01 < 0.005 < 0.2 178 < 10 < 10 1190 0.13 12N/36W-36L01 10/31/2012 910 35 66 4 130 46 165 400 — < 1 0.16 0.2 < 0.01 < 0.005 < 0.5 165 < 10 < 10 1200 < 0.05 12N/36W-36L01 7/24/2012 880 43 65 3.9 110 41 168 420 — < 1 0.16 < 0.1 < 0.01 0.02 < 0.1 168 < 10 < 10 1190 0.19 12N/36W-36L01 4/18/2012 880 47 52 3.2 95 36 180 450 — < 1 0.12 < 0.2 < 0.01 < 0.005 < 0.2 180 < 10 < 10 1190 < 0.1 12N/36W-36L01 1/11/2012 790 41 64 4.1 120 44 170 380 — < 1 0.19 0.18 < 0.02 < 0.005 < 0.2 170 < 10 < 10 1190 < 0.1 12N/36W-36L01 11/21/2011 910 39 55 3.5 110 40 180 380 — < 1 0.16 < 0.2 < 0.01 < 0.005 < 0.2 180 < 10 < 10 1200 < 0.1 12N/36W-36L01 7/25/2011 890 40.5 65 5.7 110 43 170 408.9 — < 1 0.15 < 0.1 < 0.01 < 0.005 < 0.1 170 < 5 < 5 1200 0.024 12N/36W-36L01 4/21/2011 890 42 61 4.2 100 30 170 415 — < 1 0.19 0.07 < 0.01 < 0.005 < 0.1 170 < 2 < 2 1200 ND 12N/36W-36L01 1/24/2011 890 41 55 5.1 98 36 180 400 — < 1 0.2 0.15 < 0.1 < 0.005 < 0.1 180 < 2 < 2 1200 < 0.1 12N/36W-36L01 10/21/2010 910 38 76 3.6 130 47 169 400 — < 1 0.1 < 0.1 ND < 0.005 < 0.3 169 < 10 < 10 1213 < 0.1 12N/36W-36L01 7/27/2010 707 36 64.2 3.7 127 47.4 182 420 — < 0.5 0.158 < 0.1 < 0.1 < 0.005 0.11 182 < 1 < 1 1100 < 0.1 12N/36W-36L01 4/26/2010 860 42 70.3 4.13 129 48.9 191 400 — 0.77 0.223 < 0.1 0.15 0.057 0.14 191 < 1 < 1 1100 4.53 12N/36W-36L01 10/21/2009 856 38 72 4.64 131 48.2 192 420 — 0.84 0.15 0.12 < 0.1 0.0994 0.13 192 < 1 < 1 1100 1.68 12N/36W-36L01 8/20/2009 890 39 78 4.21 138 48.1 184 390 — 0.56 ND < 0.1 < 0.1 0.185 0.14 184 < 1 < 1 1200 2.03 12N/36W-36L01 5/11/2009 832 63 83.8 4.88 111 45.4 204 330 — ND ND 0.12 ND 0.551 0.22 204 < 1 < 1 1200 4.02 12N/36W-36L01 3/26/1996 882 35 66 4.8 124 47 233 408 — ND 0.24 ND ND ND ND ND ND ND ND ND 12N/36W-36L01 6/8/1976 936 38 72 3.5 130 48 223 423 — ND 0.15 0.7 ND ND ND ND ND ND ND ND 12N/36W-36L02 10/16/2024 806 82 103 5.94 92.9 40.8 251 210 ND 1.71 0.339 J ND ND 0.125 B 0.55 251 ND ND 1190 0.0580 J 12N/36W-36L02 4/18/2024 758 85 109 B 5.92 95.4 41.9 252 230 ND 2.83 0.358 J 0.078 J 2.1 0.119 0.59 252 ND ND 1210 0.132 J 12N/36W-36L02 10/12/2023 960 92 100 5.8 96 41 270 240 < 0.02 1.7 0.34 0.15 0.19 0.14 0.62 270 < 3 < 3 1200 < 0.014 12N/36W-36L02 7/6/2023 860 94 93 5.3 85 39 250 250 — 1.4 0.26 0.16 0.18 0.13 0.62 250 < 3 < 3 1200 < 0.014 12N/36W-36L02 4/13/2023 790 94 110 5.6 94 40 260 250 < 0.02 1.3 0.29 0.14 0.16 0.13 0.59 260 < 3 < 3 1200 0.11 12N/36W-36L02 2/9/2023 770 88 97 5.3 99 43 270 260 < 0.02 < 1 0.28 0.14 0.17 0.17 0.54 270 < 3 < 3 1200 0.034 12N/36W-36L02 10/5/2022 840 96 110 5.8 100 46 250 260 < 0.01 1.7 0.33 0.091 0.12 0.15 0.61 250 < 8.2 < 8.2 1210 < 0.03 12N/36W-36L02 7/12/2022 810 98 93 5.2 87 40 260 250 < 0.01 1.9 0.32 0.096 0.12 0.13 0.4 260 < 8.2 < 8.2 1220 < 0.03 12N/36W-36L02 4/6/2022 780 93 94 5.2 85 38 250 250 < 0.05 1.9 0.3 0.063 0.13 0.13 0.5 250 < 8.2 < 8.2 1210 < 0.05 12N/36W-36L02 1/6/2022 800 95 96 5.4 87 39 250 250 0.016 J 1.7 0.31 0.076 0.12 0.14 0.61 250 < 8.2 < 8.2 1210 < 0.05 12N/36W-36L02 10/6/2021 760 93 110 5.7 96 41 260 230 < 0.05 1.5 0.3 0.079 0.13 0.14 0.5 260 < 8.2 < 8.2 — 0.031 J 12N/36W-36L02 7/15/2021 820 98 100 5.4 90 39 260 240 < 0.05 2.1 0.31 0.1 0.13 0.14 0.59 260 < 8.2 < 8.2 1190 0.11 12N/36W-36L02 4/8/2021 800 99 91 4.8 77 35 270 240 0.012 J 1.8 0.28 0.099 0.13 0.12 0.57 270 < 8.2 < 8.2 1190 0.036 J 12N/36W-36L02 1/7/2021 860 98 110 6.1 100 46 260 240 < 0.01 1.8 0.34 0.096 0.18 0.16 0.43 260 < 8.2 < 8.2 1180 0.26 12N/36W-36L02 10/11/2020 870 98 98 5.4 95 40 250 250 < 0.01 1.7 0.29 0.084 0.13 0.13 0.62 250 < 8.2 < 8.2 1190 < 0.03 12N/36W-36L02 7/8/2020 930 100 110 5.8 97 42 260 240 < 0.01 1.8 0.31 0.093 0.13 0.14 0.65 260 < 8.2 < 8.2 1210 0.087 12N/36W-36L02 4/22/2020 770 100 110 6 97 40 270 230 < 0.01 2.1 0.33 0.069 0.12 0.15 0.67 270 < 8.2 < 8.2 1190 0.56 12N/36W-36L02 1/15/2020 860 100 110 6.2 100 43 260 240 < 0.01 1.9 0.35 0.085 0.16 0.16 0.35 260 < 8.2 < 8.2 1160 0.16 12N/36W-36L02 10/15/2019 780 99 120 6.3 100 41 270 240 < 0.01 2 0.35 0.078 0.13 0.17 0.66 270 < 8.2 < 8.2 1210 0.49 12N/36W-36L02 7/10/2019 1000 99 100 5.9 94 44 260 240 < 0.01 1.9 0.33 0.096 0.15 0.15 0.6 260 < 8.2 < 8.2 1200 0.14 12N/36W-36L02 4/10/2019 820 100 100 5.7 96 43 270 240 < 0.01 2 0.32 0.094 0.13 0.15 0.53 270 < 8.2 < 8.2 1220 0.17 12N/36W-36L02 1/9/2019 820 100 110 6.1 99 42 270 240 < 0.01 2.2 0.33 0.099 0.14 0.15 0.5 270 < 8.2 < 8.2 1220 0.42

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Total Dissolved
Solids Chloride Sodium Potassium Calcium Magnesium
Alkalinity,
Bicarbonate (as
CaCO3)
Sulfate Nitrite (as N) Total Kjeldahl
Nitrogen Boron Fluoride Iodide Manganese Bromide Alkalinity, Total (as CaCO3)
Alkalinity,
Carbonate (as
CaCO3)
Alkalinity,
Hydroxide (as
CaCO3)
Specific
Conductance Iron
Table A-2. NCMA Sentry Wells Water Quality Data
Well Date
12N/36W-36L02 10/10/2018 840 99 110 7.2 100 46 260 240 < 0.01 2.2 0.33 0.064 0.13 0.19 0.4 260 < 8.2 < 8.2 1200 5.2 12N/36W-36L02 7/10/2018 800 100 99 5.6 89 41 260 240 < 0.01 2 0.33 0.14 0.14 0.14 0.62 260 < 8.2 < 8.2 1260 0.9 12N/36W-36L02 4/11/2018 850 100 110 6 96 42 260 230 < 0.01 1.8 0.32 0.097 0.16 0.17 0.66 260 < 8.2 < 8.2 1210 2.1 12N/36W-36L02 1/11/2018 800 100 110 6.3 97 44 260 230 < 0.01 2 0.38 0.12 0.17 0.17 0.65 260 < 8.2 < 8.2 1190 0.51 12N/36W-36L02 10/11/2017 830 100 100 5.9 97 44 280 230 < 0.01 1.8 0.36 0.087 0.13 0.16 0.66 280 < 8.2 < 8.2 1220 0.41 12N/36W-36L02 7/12/2017 940 97 100 6.1 98 45 250 230 < 0.01 2.2 0.32 0.096 0.13 0.16 0.59 250 < 8.2 < 8.2 1200 0.75 12N/36W-36L02 4/12/2017 780 97 120 6.7 98 43 250 240 < 0.01 2.2 0.35 0.082 0.14 0.16 0.51 250 < 8.2 < 8.2 1190 0.77 12N/36W-36L02 1/12/2017 810 94 120 6.6 110 48 270 240 < 0.01 2 0.36 0.08 0.19 0.19 0.53 270 < 8.2 < 8.2 1200 1.1 12N/36W-36L02 10/12/2016 820 99 120 6.6 110 50 270 240 0.018 J 2 0.35 0.084 0.14 0.17 0.58 270 < 8.2 < 8.2 1230 0.1 12N/36W-36L02 7/19/2016 820 97 110 6.2 95 45 270 240 — 2 0.33 0.081 0.1 0.15 0.65 270 < 8.2 < 0.82 1220 0.14 12N/36W-36L02 4/12/2016 800 96 100 6 94 44 270 230 — 1.8 0.32 0.12 0.12 0.14 0.81 270 < 8.2 < 0.82 1240 0.37 12N/36W-36L02 1/14/2016 860 96 110 6.4 99 47 260 230 — 1.6 0.34 0.1 0.078 0.17 0.65 260 < 8.2 < 8.2 1240 1.9 12N/36W-36L02 10/15/2015 800 89 96 6 91 0.15 266 230 — 2.2 0.32 0.22 0.098 0.15 0.37 266 < 10 < 10 1220 0.32 12N/36W-36L02 7/16/2015 840 97 120 5.9 110 46 260 240 — 2.44 0.34 0.11 0.11 0.15 0.59 260 < 10 < 10 1230 0.16 12N/36W-36L02 4/14/2015 800 98 88 5.3 83 39 270 240 — 2.9 0.33 0.104 0.089 0.13 0.38 270 < 10 < 10 1180 0.4 12N/36W-36L02 1/13/2015 820 100 91 5.5 86 39 250 250 — 2.2 0.31 0.105 0.09 0.13 0.322 250 < 10 < 10 1190 0.077 12N/36W-36L02 10/15/2014 800 88 96 6.4 91 40 260 210 — 2.1 0.32 < 0.1 0.092 0.14 0.358 260 < 10 < 10 1230 0.12 12N/36W-36L02 7/30/2014 800 98 99 5.8 88 39 280 210 — 2.4 0.28 0.11 0.09 0.14 0.19 280 < 10 < 10 1240 0.27 12N/36W-36L02 4/16/2014 820 95 89 6.3 73 31 280 210 — 2.3 0.31 < 0.1 0.09 0.13 0.35 280 < 10 < 10 1240 0.22 12N/36W-36L02 1/16/2014 800 100 87 5 76 33 270 230 — 2.3 0.31 0.23 0.09 0.14 0.44 270 < 10 < 10 1230 0.41 12N/36W-36L02 10/16/2013 810 90 110 6.4 91 40 260 240 — 2.2 0.32 < 0.1 0.1 0.15 0.32 260 < 10 < 10 1220 0.54 12N/36W-36L02 7/10/2013 790 105 94 5.8 88 38 260 240 — 2.5 0.34 < 0.1 0.08 0.13 0.11 260 < 10 < 10 1240 0.31 12N/36W-36L02 4/11/2013 830 100 99 6.2 83 37 260 220 — 2.2 0.35 < 0.1 0.098 0.14 0.45 260 < 10 < 10 1240 0.6 12N/36W-36L02 1/15/2013 770 110 110 6.7 84 38 265 220 — 2.8 0.36 < 0.1 0.02 0.14 0.2 265 < 10 < 10 1240 0.61 12N/36W-36L02 10/31/2012 800 100 120 7.3 90 39 265 200 — 2.4 0.4 0.34 0.12 0.14 0.34 265 < 10 < 10 1250 0.3 12N/36W-36L02 7/24/2012 800 134 125 7.4 83 35 277 200 — 2.3 0.42 0.13 0.12 0.14 0.31 277 < 10 < 10 1250 0.52 12N/36W-36L02 4/18/2012 770 130 95 6.2 75 33 270 210 — 4 0.35 0.36 0.12 0.13 < 0.2 270 < 10 < 10 1250 0.77 12N/36W-36L02 1/11/2012 900 122 110 7.2 95 37 290 170 — 4.8 0.48 0.28 < 0.02 0.17 0.45 290 < 10 < 10 1250 1.8 12N/36W-36L02 11/21/2011 780 130 95 6.1 77 33 270 160 — < 1 0.4 < 0.2 < 0.01 0.13 0.45 270 < 10 < 10 1240 0.4 12N/36W-36L02 7/25/2011 790 128.8 110 9.1 74 33 280 177 — 2.3 0.36 0.123 0.14 0.13 0.511 280 < 5 < 5 1280 2.3 12N/36W-36L02 4/21/2011 770 120 90 5.3 86 26 280 206 — 2.3 0.24 0.26 0.14 0.004 0.57 280 < 2 < 2 1270 ND 12N/36W-36L02 1/24/2011 800 120 95 7.6 75 30 300 190 — 2.3 0.39 0.16 1.31 0.13 0.53 300 < 2 < 2 1270 1.4 12N/36W-36L02 10/21/2010 770 120 130 7.6 89 44 275 160 — 3.4 0.48 < 0.1 ND 0.15 0.54 275 < 10 < 10 1293 0.12 12N/36W-36L02 7/27/2010 737 110 121 7.81 91.1 38.9 268 190 — < 0.5 0.427 0.1 0.77 0.18 0.8 268 < 1 < 1 1200 0.845 12N/36W-36L02 4/26/2010 720 100 116 6.88 85.4 32.4 215 210 — 0.77 0.382 0.2 0.28 0.167 0.7 215 < 1 < 1 1100 3.87 12N/36W-36L02 10/21/2009 638 99 113 6.15 81.6 23 172 200 — 3.2 0.268 0.33 57 0.128 0.61 172 < 1 < 1 940 0.255 12N/36W-36L02 8/20/2009 785 100 131 6.66 89.8 36.6 290 190 — 3.8 ND 0.15 0.27 0.307 0.75 290 < 1 < 1 1200 0.83 12N/36W-36L02 5/11/2009 775 120 132 7.24 84 39.7 294 180 — ND ND 0.18 ND 0.426 0.78 294 < 1 < 1 1300 0.958 12N/36W-36L02 3/26/1996 772 127 130 8.7 86 36 390 148 — ND 0.5 ND ND ND ND ND ND ND ND ND 12N/36W-36L02 6/8/1976 820 126 118 6.6 94 44 393 184 — ND ND 0.5 ND ND ND ND ND ND ND ND 12N/35W-32C03 10/17/2024 315 68 67.2 2.8 14.8 6.64 56.6 32 9.1 H H3 ND 0.0895 J ND ND ND 0.18 56.6 ND ND 470 ND 12N/35W-32C03 4/19/2024 304 74 70.3 B 2.76 15.9 7.13 70.6 35 8.6 0.86 0.0936 J 0.055 J ND 0.00200 J 0.16 70.6 ND ND 501 ND 12N/35W-32C03 10/12/2023 290 73 71 3 17 7.3 71 38 < 0.02 < 0.41 0.09 J 0.079 J 0.0096 < 0.0045 0.21 71 < 3 < 3 490 < 0.014 12N/35W-32C03 7/6/2023 310 65 70 2.8 15 6.7 57 29 — < 0.41 0.067 J 0.079 J 0.00055 < 0.0045 0.23 57 < 3 < 3 490 < 0.014 12N/35W-32C03 4/13/2023 360 70 69 2.7 14 6.4 81 37 < 0.02 < 0.41 0.081 J 0.1 ND < 0.0045 0.21 81 < 3 < 3 480 < 0.014 12N/35W-32C03 2/9/2023 310 70 68 2.7 15 6.8 67 32 < 0.02 < 0.41 0.077 J 0.084 J 0.001 < 0.0045 0.2 67 < 3 < 3 480 < 0.014 12N/35W-32C03 10/5/2022 320 71 67 2.6 14 7 56 28 < 0.01 < 0.088 0.085 J 0.042 J < 0.005 < 0.004 0.21 56 < 4.1 < 4.1 483 < 0.03 12N/35W-32C03 7/11/2022 330 73 68 2.7 14 6.5 59 30 < 0.01 0.47 0.11 0.042 J < 0.005 < 0.004 0.086 J 59 < 4.1 < 4.1 488 < 0.03 12N/35W-32C03 4/5/2022 310 74 62 2.5 14 6.1 58 33 < 0.05 < 0.2 0.11 0.044 J < 0.1 < 0.01 0.18 J 58 < 4.1 < 4.1 499 < 0.05 12N/35W-32C03 1/4/2022 340 74 64 2.5 14 6.7 59 32 < 0.05 < 0.2 0.087 J 0.042 J < 0.1 < 0.01 0.18 J 59 < 4.1 < 4.1 499 < 0.05 12N/35W-32C03 10/7/2021 320 76 68 2.6 15 6.5 56 32 < 0.05 < 0.2 0.078 J 0.053 < 0.1 < 0.01 0.18 J 56 < 4.1 < 4.1 — 0.054 12N/35W-32C03 7/15/2021 360 77 66 2.6 15 6.7 56 32 < 0.05 0.091 J 0.066 J 0.047 J 0.014 J < 0.01 0.2 56 < 4.1 < 4.1 503 0.11 12N/35W-32C03 4/6/2021 330 77 69 2.6 15 7.2 54 31 < 0.01 0.098 J 0.088 J 0.045 J < 0.005 < 0.004 0.21 54 < 4.1 < 4.1 — < 0.03 12N/35W-32C03 1/6/2021 310 71 65 2.7 14 6.5 56 29 < 0.01 0.27 0.11 0.041 < 0.005 < 0.004 0.17 56 < 4.1 < 4.1 471 < 0.03 12N/35W-32C03 10/8/2020 350 64 63 2.5 13 5.9 54 26 < 0.01 < 0.088 0.11 0.066 < 0.005 < 0.004 0.18 J 54 < 4.1 < 4.1 430 < 0.03 12N/35W-32C03 7/7/2020 290 62 66 2.7 13 6 49 25 < 0.01 < 0.088 0.11 0.049 J < 0.01 < 0.004 0.18 J 49 < 4.1 < 4.1 422 < 0.03

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City of Arroyo Grande 1
2024 CIP Update
Supply & Demand Assessment
Technical Memorandum
Date: 8/4/2025
To: Shannon Sweeney, P.E.

CC: Shane Taylor
Prepared By: Spencer Waterman
Reviewed By: Michael Steele, P.E. & Joshua Reynolds, P.E.

Project: 2024 CIP Update
Subject: Supply & Demand Assessment
This Supply & Demand Assessment Technical Memorandum (TM) was prepared for the City of Arroyo Grande (City) to assess potential supply portfolios and their ability to meet future demand considering changes to supply conditions since the City’s 2020 Urban Water Management Plan (UWMP). This TM updates supply projections, incorporating new assumptions based on the ability to store unused Lopez Reservoir entitlement, removal of Central Coast Blue as a potential supply, new demand patterns, and other new data available since completion of the 2020 UWMP.

Changes to the Lopez Reservoir contract with the San Luis Obispo County Flood Control and Water Conservation District (District) provide new opportunities for supply portfolio management and additional water reliability. This TM incorporates estimates of Lopez storage considering climate change impacts, evaporative water losses, spill losses, provisions of the updated Lopez Reservoir contract, and evaluates some potential future changes to downstream release requirements potentially impacting municipal entitlements1.

On June 30, 2024, the City withdrew from the Joint Exercise of Powers Agreement for the Central Coast Blue Project, resulting in a reduction of assumed groundwater production volume than was assumed in the 2020 UWMP.

The following sections of this TM describe the anticipated estimates of Lopez storage considering supply portfolio changes and future demands through buildout under average and dry years conditions.
1 This analysis was originally prepared in Fall 2024 prior to the decision on November 27, 2024 in the San Luis Obispo Coastkeeper v. County of San Lusis Obispo case and does not incorporate any of the results of the preliminary injunction. Litigation is ongoing which could result in impacts to Lopez supplies and storage that could change the findings of this analysis.

ATTACHMENT 2

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City of Arroyo Grande 2
2024 CIP Update
Supply & Demand Assessment

1.0 Updates to 2020 UWMP
Projections
The City delivers both groundwater and surface water through its pressurized distribution system. The City currently extracts groundwater from the Santa Maria River Valley Groundwater basin (SMGB) and the Pismo Formation, which is separate from the SMGB. The City has an entitlement of 1,323 AFY of groundwater from the SMGB based on the Santa Maria Valley Water Conservation District vs. City of Santa Maria, et al. Case No. 770214 Judgment After Trial (Judgment) for the SMGB. However, the 2020 UWMP noted that groundwater modeling indicated only 27% of groundwater entitlement (357 AFY for the City) can be pumped on a longterm consistent basis. Based on direction from City staff, a draft target of 310 AFY of pumping was conservatively assumed for this TM’s analysis. The 2020 UWMP assumes 160 AFY was reliably available from the Pismo Formation. However, due to current staff capabilities, only 80 AFY of the 160 AFY available from the Pismo Formation can be pumped at this time, so 80 AFY of supply was used in this TM. The 2020 UWMP assumed 200 AFY of supply would be available from Central Coast Blue, whereas this TM does not. The City’s current Lopez Reservoir entitlement is 2,290 AFY but is subject to reduction in drought depending on reservoir levels and other conditions. Current litigation over downstream releases at Lopez Reservoir has the potential to significantly impact both supply and storage at the lake, but ultimate impacts on supply availability are uncertain at the time of writing this TM.

Table 1-1 shows the updated projections for the total supply and demand projection under normal (average) conditions based on current staff capability. The available supplies during a normal year represent 50% of Pismo Formation production capabilities, 100% Lopez Reservoir entitlements, and reduced pumping of the City’s groundwater entitlement to the Northern Cities Management Area (NCMA) portion of the SMGB to protect against seawater intrusion.

Demands were estimated using a gallons per capita per day (GPCD) method that projected annual demands based on the assumption that the future GPCD will trend toward 100 GPCD by 2025 and stay constant thereafter based on direction from City staff and informed by GPCD usage trends over the past few years. Regulations for Making Conservation a California Way of Life require the City to reduce water to approximately 114 GPCD by 2040, which is higher than the estimated demands. If demands rebound in future years, these projections should be updated to reflect increased demand.

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City of Arroyo Grande 3
2024 CIP Update
Supply & Demand Assessment
Table 1-1. Normal Year Supply and Demand Comparison
2025 2030 2035 2040 2045
Santa Maria
Groundwater Basin
310 310 310 310 310
Pismo Formation 80 80 80 80 80
Lopez Reservoir 2,290 2,290 2,290 2,290 2,290
Supply Totals 2,680 2,680 2,680 2,680 2,680
Demand Totals 2,035 2,075 2,116 2,157 2,200
Surplus: 442 396 349 300 251
The supply reliability of the City’s surface water entitlement from Lopez Reservoir is based on reservoir storage, historical and projected production, and delivery volumes in average, single dry, and consecutive dry years conditions. The Low Reservoir Response Plan (LRRP) was adopted in December 2014 and initiated in April 2015 and August 2021 due storage being below 20,000 AF. Storage levels went below 15,000 AF in 2021 and 2022, which resulted in a proactive 20% entitlement reduction in anticipation of storage levels dropping below 10,000 AF.

However, the Zone 3 Advisory Committee endorsed an end of the LRRP and return to 100% Lopez Entitlements retroactive to April 1, 2022, following significant rainfall in January 2023.

Without Zone 3 contractors’ proactive entitlement reduction of 20% in 2022 and the significant amounts of rainfall in January 2023, the reservoir could have been below 10,000 AF in storage, which would have required a 20% entitlement reduction (which had already been voluntarily enacted by the member agencies). The enactment of the LRRP results in percentage decreases in municipal and downstream releases as shown in Table 1-2. For the purpose of projecting future dry years conditions, the 2020 UWMP and this TM assume that Lopez entitlement will be 100% in the first three dry years, 90% in the fourth dry year, and 80% in the fifth dry year. This analysis should be updated if any changes to the LRRP are enacted.

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City of Arroyo Grande 4
2024 CIP Update
Supply & Demand Assessment
Table 1-2. Initial Prescribed Municipal Diversion Reduction Strategy Under the LRRP

AMOUNT OF WATER IN

STORAGE (AF)

MUNICIPAL DIVERSION

REDUCTION

MUNICIPAL DIVERSION
(AFY)1

CITY OF ARROYO GRANDE

ENTITLEMENT
20,000 0% 4,530 2,290
15,000 10% 4,077 2,061
10,000 20% 3,624 1,832
5,000 35%(2) 2,941 1,489
4,000 100% 0 0
1 The actual amount of water diverted may vary as agencies extend the delivery of their Lopez entitlement. 2 The 35% reduction provides sufficient water to supply 55 gallons per capita per day (gpcd) for the estimated population of the Zone 3 agencies (47,696 in 2010 per the 2010 Zone 3 UWMP). 55 gpcd is the target residential indoor water usage standard used in California Department of Water Resource’s 2010 UWMP Method 4 Guidelines.

2.0 Projections with Lopez Storage
The projected demands and normal and dry years supplies2 were calculated for 2025-2045 with incorporation of unused Lopez entitlement being “banked” or stored. As described previously, it is assumed that historic Lopez entitlement for 2018-2022 will occur in the future as 100% of entitlement in the first three dry years, 90% in the fourth dry year, and 80% in the fifth dry year. Table 2-2 shows historic and projected supply and demand under average and dry years conditions assuming unused Lopez entitlement can be stored. However, for a more realistic projection, Table 2-3 additionally incorporates impacts of climate change hydrology, evaporation losses, and spills from Table 25 of the Zone 3 Contract Change Modeling Results (Contract Model) report prepared for the District by Western Hydrologics in 2021. The Contract Model estimated impacts of changes to historic hydrology with climate change for 1969-2020.

As shown in Table 2-1, Contract Model inputs and assumptions for demand and production by source were compared to the assumptions developed during the analysis performed for this TM.

Although inputs are different, use of the Contract Model’s results were the best available data and were used in this TM’s analysis as shown in Table 2-3. For this TM, it was assumed that the lowest cumulative storage modeled years from 2002-2020 would repeat from 2024-2042 and that 2021-2023 (not in Contract Model dataset) conditions would be similar to conditions in 2015-2017 and would occur in 2043-2045. Figure 2-1 shows production by source, Lopez losses, annual Lopez banked or used, and cumulative Lopez stored. 2 Normal and dry year supplies for 2024-2045 calculations are based on conditions from 2002-2023, which is a 22-year observation period.

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City of Arroyo Grande 5
2024 CIP Update
Supply & Demand Assessment
The City’s practical storage in Lopez Lake is limited to an estimated 1,200 acre-feet due to physical constraints and typical hydrological conditions, based on estimates by City staff.

Estimating predicted storage volumes that incorporate all inflows, outflows, contract requirements, capacity constraints, and other conditions was outside the scope of this analysis.

Cumulative storage projected in this analysis reflects a theoretical amount without this constraint.

Based on the results summarized in Table 2-3 and Figure 2-1, the City can meet projected demands with expected supplies and Lopez storage through buildout provided that supply assumptions do not change. Section 3.0 describes conditions that may impact supply reliability and sufficiency.

Table 2-1. Comparison of TM and Contract Model Input Assumptions TM Assumption (AFY) Contract Model Assumption
(AFY)
Demand 2,015- 2,178 2,510
Lopez Use 2,290 2,290
SMGB Production 310 330
Pismo Formation Production 80 N/A
Total Supply 2,680 2,620

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City of Arroyo Grande 6
2024 CIP Update
Supply & Demand Assessment
Table 2-2. Historic and Projected Supply & Demand with Lopez Storage Full Lopez Entitlement Lopez Drought Entitlement Lopez Banked with Drought Entitlement Pismo
Formation SMGB Total Groundwater Lopez Lopez Cumulative Lopez Lopez Lopez Lopez Lopez Lopez Lopez Year Population GPCD
Historic &
Projected
Demand
Production Production Production Production Banked Banked Multi-Dry Yrs Entitlement %
Multi-Dry Yrs
Base Year Entitlement Entitlement Used
Banked
Used
Banked
Cumulative
Banked
2010 16,908 156 2,956 610 2,346 100% 2010
2011 17,043 153 2,922 349 2,573 100% 2011
2012 17,179 157 3,022 330 2,692 100% 2012
2013 17,314 160 3,112 389 2,723 100% 2013
2014 17,450 141 2,752 120 2,632 100% 2014
2015 17,636 113 2,239 87 2,152 90% 2015
2016 17,620 99 1,948 244 1,704 90% 2016
2017 17,604 111 2,194 134 2,060 100% 2017
2018 17,588 112 2,212 49 2,163 100% 2018
2019 17,573 109 2,138 104 2,034 100% 2019
2020 17,641 117 2,319 77 2,242 100% 2020
2021 17,963 115 2,311 153 2,158 90% 2021
2022 17,963 99 1,990 168 1,822 80% 2022
2023 17,848 97 1,936 69 1,867 100% 2023/ 2001
2024 17,918 101 2,020 59 59 1,965 690 690 100% 2024/ 2002 2,290 1,961 - 329 329 2025 17,988 100 2,015 80 310 390 1,625 665 1,355 100% 2003 2,290 1,625 - 665 994 2026 18,058 100 2,023 80 310 390 1,633 657 2,012 100% 2004 2,290 1,633 - 657 1,651 2027 18,128 100 2,031 80 310 390 1,641 649 2,662 100% 2005 2,290 1,641 - 649 2,301 2028 18,199 100 2,039 80 310 390 1,649 641 3,303 100% 2006 2,290 1,649 - 641 2,942 2029 18,270 100 2,046 80 310 390 1,656 634 3,937 100% 2007 2,290 1,656 - 634 3,576 2030 18,341 100 2,054 80 310 390 1,664 626 4,562 100% 2008 2,290 1,664 - 626 4,201 2031 18,413 100 2,062 80 310 390 1,672 618 5,180 100% 2009 2,290 1,672 - 618 4,819 2032 18,485 100 2,071 80 310 390 1,681 609 5,789 100% 2010 2,290 1,681 - 609 5,428 2033 18,557 100 2,079 80 310 390 1,689 601 6,391 100% 2011 2,290 1,689 - 601 6,030 2034 18,629 100 2,087 80 310 390 1,697 593 6,984 100% 2012 2,290 1,697 - 593 6,623 2035 18,702 100 2,095 80 310 390 1,705 585 7,569 100% 2013 2,290 1,705 - 585 7,208 2036 18,775 100 2,103 80 310 390 1,713 577 8,146 100% 2014 2,290 1,713 - 577 7,785 2037 18,848 100 2,111 80 310 390 1,721 569 8,715 90% 2015 2,061 1,721 - 340 8,125 2038 18,921 100 2,119 80 310 390 1,729 561 9,275 90% 2016 2,061 1,729 - 332 8,456 2039 18,995 100 2,128 80 310 390 1,738 552 9,828 100% 2017 2,290 1,738 - 552 9,009 2040 19,069 100 2,136 80 310 390 1,746 544 10,372 100% 2018 2,290 1,746 - 544 9,553

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City of Arroyo Grande 7
2024 CIP Update
Supply & Demand Assessment
Full Lopez Entitlement Lopez Drought Entitlement Lopez Banked with Drought Entitlement Pismo
Formation SMGB Total Groundwater Lopez Lopez Cumulative Lopez Lopez Lopez Lopez Lopez Lopez Lopez 2041 19,144 100 2,144 80 310 390 1,754 536 10,907 100% 2019 2,290 1,754 - 536 10,088 2042 19,218 100 2,153 80 310 390 1,763 527 11,434 100% 2020 2,290 1,763 - 527 10,615 2043 19,293 100 2,161 80 310 390 1,771 519 11,953 90% 2021 2,061 1,771 - 290 10,905 2044 19,368 100 2,170 80 310 390 1,780 510 12,464 80% 2022 1,832 1,780 - 52 10,958 2045 19,444 100 2,178 80 310 390 1,788 502 12,966 100% 2023 2,290 1,788 - 502 11,460 1 Includes surplus water for 2024. Future surplus water not included in projections.

Table 2-3. Historic and Projected Supply & Demand with Lopez Storage and Impacts of Climate Change Hydrology, Evaporation, & Spills Lopez Drought Entitlement Lopez Banked with Drought Entitlement + Climate Change Hydrology, Evaporation, & Spills
Lopez Lopez Lopez Lopez Lopez Lopez Lopez Lopez
Year Population GPCD Historic & Projected
Demand
Multi-Dry
Yrs
Multi-Dry Yrs
Base Year Entitlement Modeling Year Spills for AG Evap Loss for City Banked/(Used) Cumulative
Banked
2010 16,908 156 2,956 100% 2010
2011 17,043 153 2,922 100% 2011
2012 17,179 157 3,022 100% 2012
2013 17,314 160 3,112 100% 2013
2014 17,450 141 2,752 100% 2014
2015 17,636 113 2,239 90% 2015
2016 17,620 99 1,948 90% 2016
2017 17,604 111 2,194 100% 2017
2018 17,588 112 2,212 100% 2018
2019 17,573 109 2,138 100% 2019
2020 17,641 117 2,319 100% 2020
2021 17,963 115 2,311 90% 2021
2022 17,963 99 1,990 80% 2022
2023 17,848 97 1,936 100% 2023/ 2001
2024 17,918 101 2,020 100% 2024/ 2002 2,290 2002 - 14 315 315 2025 17,988 100 2,015 100% 2003 2,290 2003 - 23 642 957 2026 18,058 100 2,023 100% 2004 2,290 2004 - 34 623 1,580 2027 18,128 100 2,031 100% 2005 2,290 2005 583 6 60 1,641 2028 18,199 100 2,039 100% 2006 2,290 2006 249 0 392 2,033 2029 18,270 100 2,046 100% 2007 2,290 2007 - 9 625 2,658 2030 18,341 100 2,054 100% 2008 2,290 2008 - 16 610 3,267 2031 18,413 100 2,062 100% 2009 2,290 2009 - 27 591 3,858

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City of Arroyo Grande 8
2024 CIP Update
Supply & Demand Assessment
Lopez Drought Entitlement Lopez Banked with Drought Entitlement + Climate Change Hydrology, Evaporation, & Spills
2032 18,485 100 2,071 100% 2010 2,290 2010 - 28 581 4,439 2033 18,557 100 2,079 100% 2011 2,290 2011 745 1 -145 4,295 2034 18,629 100 2,087 100% 2012 2,290 2012 - 6 587 4,882 2035 18,702 100 2,095 100% 2013 2,290 2013 - 15 570 5,452 2036 18,775 100 2,103 100% 2014 2,290 2014 - 25 552 6,004 2037 18,848 100 2,111 90% 2015 2,061 2015 - 36 304 6,308 2038 18,921 100 2,119 90% 2016 2,061 2016 - 57 275 6,582 2039 18,995 100 2,128 100% 2017 2,290 2017 - 58 494 7,077 2040 19,069 100 2,136 100% 2018 2,290 2018 - 62 482 7,559 2041 19,144 100 2,144 100% 2019 2,290 2019 - 31 505 8,063 2042 19,218 100 2,153 100% 2020 2,290 2020 - 39 488 8,551 2043 19,293 100 2,161 90% 2021 2,061 2015/ 2021 - 36 254 8,805 2044 19,368 100 2,170 80% 2022 1,832 2016/ 2022 - 57 -5 8,801 2045 19,444 100 2,178 100% 2023 2,290 2017/ 2023 - 58 444 9,245

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City of Arroyo Grande 9
2024 CIP Update
Supply & Demand Assessment
Figure 2-1. Historic and Projected Supply & Demand with Lopez Storage and Impacts of Climate Change Hydrology, Evaporation, & Spills (2,000)
-
2,000
4,000
6,000
8,000
10,000
2024 2025 2026 2027 2028 2029 2030 2031 2032 2033 2034 2035 2036 2037 2038 2039 2040 2041 2042 2043 2044 2045 Production by Source & Lopez Storage
Lopez Cumulative Banked Pismo Formation Production SMGB Production Lopez Production Lopez Spills for AG Lopez Evap Loss for City Lopez Banked Historic & Projected Demand Practical Lopez Storage Space Available

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City of Arroyo Grande 10
2024 CIP Update
Supply & Demand Assessment

3.0 Potential Future Impacts
There is a potential that Lopez storage could change in the future based on changes in hydrology, infrastructure, operations, or impacts from legal or contractual changes due to environmental needs for downstream releases. Reductions to Lopez entitlements and downstream releases during shortages are currently subject to the LRRP, which has been developed to provide an initial set of prescribed actions combined with an adaptive management approach. The purpose of the LRRP is to act as the guiding document during drought emergencies, as outlined in the Interim Downstream Release Schedule (IDRS).

According to the LRRP, an alternate downstream reduction strategy that could be implemented through adaptive management includes a Habitat Conservation Plan (HCP) downstream release strategy. As shown in Figure 3-1 and Table 3-1, the IDRS shows potential downstream release requirements based on the IDRS and a draft HCP. Based on those downstream scenarios, it is assumed that downstream releases could increase by 3%-6% thus potentially reducing the City’s entitlement by 3%-6%, which yields the cumulative storage amounts shown in Figure 3-2. If downstream releases were to increase enough, or another condition occurs, to reduce the City’s annual entitlement by approximately 25% (~580 AFY) or more, the City would likely not have any cumulative Lopez storage at the end of the analysis period, all other assumptions being equal. Impacts from the preliminary injunction have not been included in this analysis and any resulting changes in entitlements, if any, should be evaluated through updated analysis once known.

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City of Arroyo Grande 11
2024 CIP Update
Supply & Demand Assessment
Figure 3-1. IDRS Downstream Release Rates

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City of Arroyo Grande 12
2024 CIP Update
Supply & Demand Assessment
Table 3-1. Potential Downstream Release Rates Impacts to Entitlements Month Current
(cfs)
Current
(cfs)
IDRS
Modified
(CFS)
IDRS
(cfs)
Current
(AF)
Current
(AF)
IDRS
Modified
(AF)
IDRS
(AF)
Oct 6 6.19 6 6 369 381 369 369
Nov 6 6.19 6 6 357 368 357 357
Dec 6 6.19 6 6 369 381 369 369
Jan 6 6.19 4.86 3 369 381 299 184
Feb 6 6.19 4.86 3 333 344 270 167
Mar 6 6.19 4.86 3 369 381 299 184
Apr 6 6.19 6 6 357 368 357 357
May 6 6.19 6 6 369 381 369 369
Jun 6 6.19 6 6 357 368 357 357
Jul 6 6.19 6 6.19 369 381 369 381
Aug 6 6.19 6 6.19 369 381 369 381
Sep 6 6.19 6 3 357 368 357 179
Total 0 0 0 0 4,344 4,481 4,140 3,653
Downstream Release Portion of Safe Yield (AF) 4,200 4,200 4,200 4,200 Flow Scenario Difference from Downstream Release
Safe Yield (AF) -144 -281 60 547
Arroyo Grande's Portion of Entitlement Change (AF) -73 -142 30 277 Arroyo Grande's Portion of Entitlement Change (%) -3% -6% 1% 12%

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City of Arroyo Grande 13
2024 CIP Update
Supply & Demand Assessment
Figure 3-2. Cumulative Storage with Various Downstream Release Scenarios

4.0 Summary and Recommendations
Based on the assumptions used in this analysis, the City’s existing water supply is anticipated to be sufficient to meet current and projected future demands through buildout. However, there is a risk that changes in entitlements or operations of any of the City’s supplies could have a significant impact on the City’s water supply portfolio. It is recommended that the City perform additional analysis if any entitlement or operational changes occur that would materially impact the City’s groundwater or surface water supply availability, or if demands trend higher than assumed.
12,966
11,460
9,245
7,887
6,635
0 2,000
4,000
6,000
8,000
10,000
12,000
14,000
Cumulative Storage or Supply Deficit (AF)
Practical Lopez Storage Space Available
Full Lopez Entitlement
Lopez Drought Entitlement
Lopez Drought Entitlement + Climate Change Hydrology, Evaporation, & Spills Lopez Drought, Climate Change Hydrology, & 3% (6 cfs per IDRS) Reduced Entitlement from Downstream Release Increases
Lopez Drought, Climate Change Hydrology, & 6% (6.19 cfs per IDRS) Reduced Entitlement from Downstream Release Increases

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Arroyo Grande City CouncilAugust 12, 2025

Arroyo Grande City Council
August 12, 2025