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¶ Introduction
Contains survey statistics of laboratory results from water samples submitted to ServiTech Laboratories during 2011 to 2022, inclusive, for analysis of irrigation water suitability. The results are grouped by National Agricultural Statistics Service (USDA-NASS) reporting districts.
¶ Figure 1. Texas East USDA-NASS Districts
Interpretation of survey results:
- Median = 50th percentile
- Typical range = 25th and 75th percentiles
- Low - High = 5th and 95th percentiles
¶ Table 1. Electrical Conductivity, EC mmho/cm |
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| Texas East Districts | Median | Typical range | Low - High |
| Cross Timbers | 1.38 | 0.70 – 2.07 | 0.48 – 4.58 |
| Blacklands | 0.98 | 0.58 – 1.34 | 0.30 – 5.39 |
| East Texas East | 0.52 | 0.25 – 1.32 | 0.10 – 3.57 |
| South Central | 1.26 | 0.80 – 2.22 | 0.41 – 6.51 |
| Coastal Districts | 0.80 | 0.49 – 1.42 | 0.08 – 5.54 |
| South Texas | 0.70 | 0.59 – 1.12 | 0.52 – 2.46 |
| Lower Valley | 2.12 | 1.49 – 3.15 | 0.93 – 7.07 |
| Eastern Texas Region | 0.98 | 0.59 – 1.47 | 0.22 – 5.37 |
¶ Table 2. Sodium Adsorption Ratio, Adjusted (SARa) |
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| Texas East Districts | Median | Typical range | Low - High |
| Cross Timbers | 2.6 | 1.6 – 5.5 | 0.5 – 59.4 |
| Blacklands | 14.5 | 2.8 – 34.6 | 0.8 – 62.3 |
| East Texas East | 2.4 | 1.1 – 9.1 | 0.2 – 27.8 |
| South Central | 12.2 | 3.6 – 19.0 | 0.6 – 67.6 |
| Coastal Districts | 3.1 | 1.6 – 6.9 | 0.2 – 27.2 |
| South Texas | 3.1 | 1.9 – 5.5 | 1.5 – 65.3 |
| Lower Valley | 8.3 | 5.0 – 13.9 | 3.9 – 24.0 |
| Eastern Texas Region | 5.8 | 2.3 – 22.5 | 0.5 – 47.4 |
¶ Table 3. Chloride, Cl mg/L |
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| Texas East Districts | Median | Typical range | Low - High |
| Cross Timbers | 220 | 42 – 365 | 10 – 1085 |
| Blacklands | 42 | 21 – 105 | 10 – 682 |
| East Texas East | 43 | 20 – 145 | 5 – 489 |
| South Central | 165 | 55 – 360 | 21 – 1175 |
| Coastal Districts | 100 | 32 – 225 | 8 – 632 |
| South Texas | 37 | 18 – 140 | 14 – 408 |
| Lower Valley | 290 | 160 – 500 | 77 – 1760 |
| Eastern Texas Region | 62.0 | 26 – 190 | 10 – 798 |
¶ Table 4. Sodium, Na mg/L |
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| Texas East Districts | Median | Typical range | Low - High |
| Cross Timbers | 100 | 40 – 178 | 9 – 810 |
| Blacklands | 190 | 57 – 292 | 17 – 819 |
| East Texas East | 38 | 21 – 125 | 6 – 355 |
| South Central | 195 | 69 – 285 | 12 – 1156 |
| Coastal Districts | 74 | 27 – 155 | 6 – 401 |
| South Texas | 62 | 32 – 96 | 25 – 538 |
| Lower Valley | 300 | 153 – 410 | 94 – 792 |
| Eastern Texas Region | 130 | 43 – 280 | 12 – 719 |
¶ Table 5. Calcium, Ca mg/L |
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| Texas East Districts | Median | Typical range | Low - High |
| Cross Timbers | 108 | 65 – 147 | 14 – 290 |
| Blacklands | 21 | 4 – 50 | 1 – 232 |
| East Texas East | 31 | 9 – 135 | 3 – 374 |
| South Central | 65 | 24 – 128 | 4 – 380 |
| Coastal Districts | 53 | 27 – 94 | 5 – 226 |
| South Texas | 72 | 53 – 85 | 6 – 210 |
| Lower Valley | 130 | 100 – 190 | 35 – 634 |
| Eastern Texas Region | 40 | 11 – 89 | 2 – 307 |
¶ Table 6. Magnesium, Mg lb/ac-ft |
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| Texas East Districts | Median | Typical range | Low - High |
| Cross Timbers | 79 | 53 – 182 | 11 – 426 |
| Blacklands | 5 | 3 – 14 | 3 – 169 |
| East Texas East | 14 | 8 – 61 | 3 – 155 |
| South Central | 42 | 17 – 95 | 3 – 242 |
| Coastal Districts | 49 | 16 – 87 | 3 – 246 |
| South Texas | 38 | 35 – 49 | 9 – 88 |
| Lower Valley | 131 | 92 – 193 | 41 – 485 |
| Eastern Texas Region | 16 | 5 – 73 | 3 – 235 |
¶ Table 7. Potassium, K as lb/ac-ft |
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| Texas East Districts | Median | Typical range | Low - High |
| Cross Timbers | 8 | 5 – 15 | 3 – 23 |
| Blacklands | 8 | 5 – 14 | 3 – 41 |
| East Texas East | 11 | 5 – 19 | 3 – 90 |
| South Central | 19 | 8 – 29 | 3 – 98 |
| Coastal Districts | 14 | 8 – 22 | 3 – 75 |
| South Texas | 16 | 11 – 16 | 5 – 32 |
| Lower Valley | 19 | 14 – 30 | 10 – 56 |
| Eastern Texas Region | 11 | 5 – 19 | 3 – 46 |
¶ Table 8. Sulfate-sulfur, SO4-S as lb/ac-ft |
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| Texas East Districts | Median | Typical range | Low - High |
| Cross Timbers | 73 | 41 – 184 | 15 – 503 |
| Blacklands | 82 | 49 – 151 | 7 – 544 |
| East Texas East | 35 | 13 – 125 | 6 – 479 |
| South Central | 90 | 35 – 315 | 5 – 1496 |
| Coastal Districts | 24 | 10 – 54 | 2 – 397 |
| South Texas | 57 | 46 – 87 | 30 – 275 |
| Lower Valley | 299 | 234 – 517 | 107 – 1061 |
| Eastern Texas Region | 75 | 33 – 163 | 5 – 890 |
¶ Table 9. Boron, B as lb/ac-ft |
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| Texas East Districts | Median | Typical range | Low - High |
| Cross Timbers | 0.27 | 0.18 – 0.50 | 0.10 – 4.23 |
| Blacklands | 1.13 | 0.46 – 2.44 | 0.16 – 6.57 |
| East Texas East | 0.27 | 0.10 – 0.48 | 0.05 – 2.88 |
| South Central | 1.22 | 0.50 – 2.54 | 0.16 – 11.59 |
| Coastal Districts | 0.35 | 0.19 – 1.12 | 0.11 – 5.33 |
| South Texas | 0.46 | 0.30 – 0.98 | 0.21 – 4.86 |
| Lower Valley | 1.85 | 1.03 – 2.72 | 0.42 – 4.17 |
| Eastern Texas Region | 0.73 | 0.30 – 1.96 | 0.11 – 6.23 |
¶ Table 10. Nitrate-nitrogen, NO3-N mg/L |
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| Texas East Districts | Median | Typical range | Low - High |
| Cross Timbers | 1.6 | 1.0 – 2.7 | 0.1 – 58.0 |
| Blacklands | 1.0 | 0.1 – 1.2 | 0.1 – 10.0 |
| East Texas East | 1.0 | 0.1 – 1.1 | 0.1 – 14.0 |
| South Central | 1.0 | 0.6 – 1.7 | 0.1 – 10.1 |
| Coastal Districts | 1.0 | 0.2 – 9.7 | 0.1 – 25.9 |
| South Texas | 1.0 | 1.0 – 1.0 | 0.1 – 9.4 |
| Lower Valley | 0.2 | 0.1 – 1.0 | 0.1 – 19.7 |
| Eastern Texas Region | 1.0 | 0.1 – 1.6 | 0.1 – 13.6 |
¶ Table 11. Bicarbonate, HCO3, lime equivalent as lb/ac-ft |
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| Texas East Districts | Median | Typical range | Low - High |
| Cross Timbers | 760 | 600 – 1025 | 280 – 1450 |
| Blacklands | 645 | 355 – 980 | 150 – 1405 |
| East Texas East | 600 | 185 – 805 | 60 – 1345 |
| South Central | 735 | 520 – 915 | 310 – 1030 |
| Coastal Districts | 560 | 400 – 705 | 30 – 950 |
| South Texas | 670 | 600 – 670 | 315 – 1480 |
| Lower Valley | 670 | 515 – 870 | 350 – 925 |
| Eastern Texas Region | 645 | 425 – 890 | 95 – 1270 |
¶ Table 12. Iron, Fe mg/L |
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| Texas East Districts | Median | Typical range | Low - High |
| Cross Timbers | 0.09 | 0.05 – 0.20 | 0.05 – 5.49 |
| Blacklands | 0.23 | 0.05 – 0.95 | 0.05 – 4.91 |
| East Texas East | 0.16 | 0.05 – 1.90 | 0.05 – 12.93 |
| South Central | 0.08 | 0.05 – 0.94 | 0.05 – 39.75 |
| Coastal Districts | 0.17 | 0.05 – 0.57 | 0.05 – 18.91 |
| South Texas | 0.11 | 0.05 – 0.28 | 0.05 – 1.32 |
| Lower Valley | 0.38 | 0.05 – 0.94 | 0.05 – 11.47 |
| Eastern Texas Region | 0.17 | 0.05 – 0.82 | 0.05 – 5.61 |
¶ Table 13. Manganese, Mn mg/L |
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| Texas East Districts | Median | Typical range | Low - High |
| Cross Timbers | 0.011 | 0.006 – 0.062 | 0.005 – 0.485 |
| Blacklands | 0.014 | 0.005 – 0.055 | 0.005 – 0.201 |
| East Texas East | 0.024 | 0.005 – 0.130 | 0.005 – 0.630 |
| South Central | 0.017 | 0.005 – 0.079 | 0.005 – 2.003 |
| Coastal Districts | 0.026 | 0.005 – 0.082 | 0.005 – 0.452 |
| South Texas | 0.010 | 0.005 – 0.035 | 0.005 – 0.070 |
| Lower Valley | 0.210 | 0.030 – 0.520 | 0.006 – 2.228 |
| Eastern Texas Region | 0.017 | 0.005 – 0.076 | 0.005 – 0.411 |
¶ Table 14. Water pH |
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| Texas East Districts | Median | Typical range | Low - High |
| Cross Timbers | 8.0 | 7.8 – 8.2 | 7.6 – 8.6 |
| Blacklands | 8.2 | 7.7 – 8.8 | 6.9 – 9.2 |
| East Texas East | 7.7 | 7.2 – 7.9 | 6.6 – 10.4 |
| South Central | 8.0 | 7.7 – 8.3 | 7.3 – 8.5 |
| Coastal Districts | 7.8 | 7.5 – 8.1 | 6.6 – 8.5 |
| South Texas | 7.9 | 7.6 – 8.1 | 7.3 – 8.3 |
| Lower Valley | 7.9 | 7.7 – 8.2 | 7.4 – 8.5 |
| Eastern Texas Region | 8.0 | 7.6 – 8.4 | 6.9 – 9.0 |
¶ Table 15. Conversion Factors |
| 1 mg/L ≈ 1 ppm |
| 1 mg/L = 1,000 µg/L |
| 1 mmho/cm = 1 dS/m |
| 1 mmho/cm = 1,000 µmho/cm lb/ac-in = mg/L x 0.2267 lb/ac-ft = mg/L x 2.7204 |
| lime equivalent, lb/ac-ft = HCO3 mg/L x 2.2304 |
| 1 acre-inch = 27,154 gallons |
| 1 acre-foot = 325,848 gallons |
¶ Table 16. Sample Count |
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| Cross Timbers | 29 |
| Blacklands | 277 |
| East Texas East | 45 |
| South Central | 56 |
| Coastal Districts | 93 |
| South Texas | 31 |
| Lower Valley | 31 |
| Eastern Texas Region | 562 |