Local and imported drinking water quality results
Average Average
Average imported MWD
local treated surface water
PHG (MCLG)
Range of detections
MCL violation? Typical source of contaminant
groundwater local treated
Chemical
MCL
Radiologicals – tested in 2024 Alpha Radiation (pCi/L)
15
0 0
1.9 NR 2.2
3.8 4.6 2.2
ND 4.0 1.0
ND - 3.8 ND - 5.0 ND - 3.0
No No No No No No No No No No No No No No No No No No No No No
Erosion of natural deposits
Beta Radiation (pCi/L)
50 20
Decay of natural and man-made deposits
Uranium (pCi/L)
0.43
Erosion of natural deposits
Inorganic chemicals – tested in 2024 Aluminum (ppm)
1
0.6
ND
ND Highest RAA = 0.105 ND - 0.110
Treatment process residue, natural deposits
Arsenic (ppb) Barium (ppm) Bromate (ppb) Chlorine (ppm)
10
0.004
2.00
<2
ND
ND - 3.04 ND - 0.134 1.5 - 3.9 ND - 0.19 ND - 0.83
Erosion of natural deposits Erosion of natural deposits
1
2
<0.100
<0.100
0.124
10
0.1 4.0
NR 2.4 0.1
NR 2.5 ND
Highest RAA = ND ND - 1.6
Byproduct of drinking water ozonation
4.0
2.5 ND NR 0.7 ND ND
Drinking water disinfectant added for treatment Erosion of natural deposits; industrial discharge
Hexavalent Chromium (ppb)
10
0.02
Erosion of natural deposits; IRWD does not add Fluoride to its local treated groundwater and surface water
Fluoride (ppm) naturally-occurring
2
1
0.29
0.35
Control range 0.6 - 1.2 ppm Optimal level 0.7 ppm
Fluoride (ppm) treatment-related
NR 2.3 2.3
NR ND ND ND 112 <3
0.6 - 0.8 ND - 4.3 ND - 4.3
Water additive for dental health
Nitrate (ppm as N)
10 10
10 10
Fertilizers, septic tanks Fertilizers, septic tanks
Nitrate+Nitrite (ppm as N)
Secondary standards* – tested in 2024 Aluminum (ppb)
200* 500*
600 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A
8.4
Highest RAA = ND ND - 110
Treatment process residue, natural deposits Leaching from natural deposits; seawater influence
Chloride (ppm) Color (color units)
41.5
104
17.8 - 124
15*
<3
2
ND - 8 ND - 6
Naturally-occurring organic substances Naturally-occurring organic materials Ions in water; seawater influence Runoff or leaching from natural deposits Runoff or leaching from natural deposits Runoff or leaching from natural deposits Runoff or leaching from natural deposits Runoff or leaching from natural deposits Runoff or leaching from natural deposits Runoff or leaching from natural deposits Runoff or leaching from natural deposits Byproduct of drinking water chlorination Erosion of natural deposits
Odor (TON)
3*
1
2
1
Specific Conductance (µmho/cm)
1,600*
490 62.1 289
1,065
979 224 621
358 - 1126 21.5 - 253 134 - 738
Sulfate (ppm)
500*
237 642
Total Dissolved Solids (ppm)
1,000*
Turbidity (NTU)
5*
<0.10
<0.10
ND
ND - 0.4
Unregulated contaminants – tested in 2024 Alkalinity, total (ppm as CaCO3)
Not regulated Not regulated Not regulated Not regulated Not regulated NL = 1 Not regulated Not regulated Not regulated Not regulated Not regulated Not regulated Not regulated NL = 800
101
124 124 0.14 0.02 72.7 <0.6 12.2 0.41 295 17.3 27.9 NR
114 NR
70 - 233 70 - 144 ND - 0.25 0.02 - 0.29 16.7 - 79.5 <0.6 - 1.1
N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A
Bicarbonate (ppm as HCO3)
96.1 0.16 0.14 35.2 <0.6
Boron (ppm) Bromide (ppm) Calcium (ppm) Carbonate (ppm) Chlorate (ppb)
0.14
NR
68.0
NR
NR
77.0 12.5 0.62 270 15.8 15.0
77.0
Corrosivity (Aggressiveness) Corrosivity (Langlier Index) Hardness, total (ppm as CaCO3) Hardness, total (grains/gal)
12.1 0.33
11.0 - 12.9
Elemental balance in water Elemental balance in water
(-)0.72 - 0.81
128
53.9 - 321 7.5 - 17.3 2.9 - 29.8 ND - 19.1
Runoff or leaching from natural deposits Runoff or leaching from natural deposits Runoff or leaching from natural deposits
7.5
Magnesium (ppm) Molybdenum (ppb)
10.1
7.9 ND 1.5 8.3 1.3
5.4 NR ND 7.9 5.9 105 1.9 2.4
NR 2.5 ND 8.2 4.9 103 2.4 ND
Drinking water treatment chemical for aesthetic quality Byproducts of drinking water chloramination; industrial processes Industrial chemical factory discharges; runoff/leaching from landfills; used in fire-retarding foams and various industrial processes
N-Nitrosodi-n-butylamine (NDBA) (ppt) Perfluorooctanoic acid (PFOA) (ppt)
2.5
NL = 5.1
0.007 (0)
ND - 2.4 7.1 - 8.6
No
pH (pH units)
Not regulated Not regulated Not regulated
N/A N/A N/A N/A N/A
N/A N/A N/A
Acidity, hydrogen ions
Potassium (ppm) Sodium (ppm)
0.65 - 21.2 25.1 - 116 0.37 - 2.5
Runoff or leaching from natural deposits Runoff or leaching from natural deposits Various natural and man-made sources Runoff or leaching from natural deposits
53.7 0.4 4.0
Total Organic Carbon (ppm)
TT
TT
Vanadium (ppb)
NL = 50
ND - 6.3
N/A
Your water has been tested for many more chemicals than are listed above, including metals (such as mercury), pesticides and volatile organic compounds. Chemicals not detected in any water sources are not included in the table. *Contaminant is regulated by a secondary standard to maintain aesthetic qualities (taste, odor, color).
ppb = parts-per-billion; ppm = parts-per-million; ppt = parts-per-trillion; pCi/L = picoCuries per liter; ntu = nephelometric turbidity units; ND = not detected; N/A = not applicable; NR = not required to be tested; < = average is less than the detection limit for reporting purposes; MCL = Maximum Contaminant Level; (MCLG) = federal MCL Goal; PHG = California Public Health Goal; µmho/cm = micromho per centimeter; NL = Notification Level; TT = Treatment Technique; RAA = Highest Running Annual Average
Turbidity – combined filter effluent
Treatment technique
Turbidity measurements
TT violation?
Typical source
Baker Water Treatment Plant 1) Highest single turbidity measurement
0.1 NTU
0.043 100%
No No
Soil run-off Soil run-off
2) Percentage of samples less than or equal to 0.3 NTU Metropolitan Water District Diemer Filtration Plant 1) Highest single turbidity measurement 2) Percentage of samples less than or equal to 0.3 NTU
100%
0.1 NTU
0.06
No No
Soil run-off Soil run-off
100%
100%
Unregulated chemicals requiring monitoring at entry points to the distribution system Chemical Notification level PHG Average local and imported Range of detections Most recent sampling date Bromide (ppm) N/A N/A 0.20 0.025 - 0.72 2020 Germanium, total (ppb) N/A N/A <0.3 ND - 0.8 2020 Manganese, total (ppb) MCL = 50* N/A 0.88 ND - 2.7 2020 Total Organic Carbon (ppm) N/A N/A 1.2 0.06 - 6.5 2020 Lithium, total (ppb) N/A N/A 51.6 ND - 166 2020 Perfluorooctanoic Acid (PFOA) (ppt) 5.1 0.007 0.19 ND - 2.3 2020 *Contaminant is regulated by a secondary standard.
IRWD Water Quality Report 2025 | Page 8
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