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Inorganic Blind Sample Project (IBSP)

Regression Equations

Regression Equation Development

The Standard Reference Samples (SRSs) used in the Inorganic Blind Sample Project are analyzed through a round-robin evaluation program described by Farrar and Long (1997). A statistical summary of the round-robin results is prepared for each set of samples. Until 1988, the SRS project used means and standard deviations in the summary reports. After 1988, the SRWS project used median and f-pseudosigma in the summary reports as a measure of location and variability. The mean or median data reported in the SRWS summaries have been referred to as most probable values (MPVs). The f-pseudosigma is defined by Hoaglin and others (2000) as:

f-pseudosigma = (data [Fourth-spread])/1.349

where the Fourth-spread is analogous to the interquartile range (3rd quartile - 1st quartile) of the data. In addition, they show that the f-pseudosigma yields an unbiased estimate of standard deviation when the data distribution is Gaussian. However, it is recognized that some of the SRWS project data sets may not have Gaussian data distributions, the regression equations will be derived from a combination of parametric and nonparametric results.

The SRS project MPVs are used to estimate the MPVs (or target values) of the Inorganic Blind Sample Project mixes based on the proportion of the SRS used. Likewise, if deionized water is used in the preparation of a blind sample mix, then a sample concentration of zero is applied to estimate the resultant MPV based on the proportion used. The resulting MPVs are used in the Inorganic Blind Sample Project to compare with analytical results.

For each constituent, a regression equation was used to estimate the f-pseudosigma (FS), over a continuous range of concentrations. The equations were derived by regressing the f-pseudosigma or standard deviation against the MPV using ordinary least-squares. Helsel and Hirsch (1992) provide a general model for estimation of ordinary least-squares regression,

FSi = β0 + β1MPVi + εi            i = 1,2,...,n

where

  FSi = the ith observation of the response (or dependent) variable, FS 
  MPVi = the ith observation of the explanatory (or independent) variable, MPV 
  β0 = the intercept
  β1 = the slope
  εi = the random error or residual for the ith observation, and 
  n = the sample size.

SRS project summary data for semi-annual round-robin sample studies (14 studies over the course of seven years) were used to derive regression equations for each constituent. The table below presents, by FY, the concentration range of SRS samples used, the derived FS equation, and the coefficient of determination.

As of FY16, reference materials are submitted unaltered from their round-robin form (except for re-bottling into NWQL-required bottle types). The MPV (or target value) and  FS  come straight from the round-robin studies coordinated by the Standard Reference Sample Project and therefore require no regression equation. (In FY16, one "trace metals" blind-sample and one "major ions" blind sample were mixed in the historical fashion; and thus, required a regression equation to determine control limits. In addition, one nutrient blind-sample is prepared with a 1:9 dilution with ASTM Type I "blank" water for low-level analytical methods. FY16 regression equations are used every year to determine control limits for this blind nutrient sample.)

 

References

Farrar, Jerry W., Long, H. Keith, 1997, Report on the U.S. Geological Survey's evaluation program for standard reference samples distributed in September 1996. U.S. Geological Survey, Open File Report 97-20 p. 9.

Hoaglin, D.C., Mosteller, F., and Tukey, J.W., Eds. 2000, Understanding robust and exploratory data analysis: New York, NY, John Wiley, Inc., p. 38-41.

 

Nutrients
Fiscal Yr Constituent Slope 1) Y-intercept0)   r2 Range used
2016 NH4 0.0462 0.005 0.75 0.07 - 1.2 mg/L
2016 NH4 + Org N 0.0629 0.046 0.52 0.1 - 1.3 mg/L
2016 NH4 + NO2 + NO3 + Org N 0.0378 0.028 0.67 0.3 - 2.3 mg/L
2016 NO2 + NO3 0.0325 0.003 0.91 0.09 - 1.4 mg/L
2016 NO2 + NO3 (low level) 0.0347 0.002 0.93 0.09 - 1.0 mg/L
2016 Orthophosphate 0.0317 0.001 0.90 0.04 - 1.5 mg/L
2016 Phosphorus 0.0310 0.004 0.85 0.04 - 1.5 mg/L
2016 Phosphorus (low level) 0.0375 0.001 0.57 0.04 - 0.2 mg/L
Trace Metals and Silica
Fiscal Yr Constituent Slope 1) Y-intercept0)   r2 Range used
2016 Aluminum 0.0611 0.881 0.90 16 - 320 µg/L
2016 Antimony 0.0419 0.024 0.89 0.06 - 5.0 µg/L
2016 Arsenic 0.0624 0.020 0.99 0.20 - 24 µg/L
2016 Barium 0.0311 0.293 0.76 6.8 - 72 µg/L
2016 Beryllium 0.0427 0.019 0.37 0.09 - 0.75 µg/L
2016 Boron 0.0472 1.615 0.45 4.6 - 69 µg/L
2016 Cadmium 0.0353 0.017 0.90 0.02 - 3.9 µg/L
2016 Chromium 0.0396 0.094 0.70 0.35 - 5.6 µg/L
2016 Cobalt 0.0462 0.013 0.96 0.09 - 5.6 µg/L
2016 Copper 0.0578 0.061 0.98 0.94 - 21 µg/L
2016 Iron 0.0460 2.926 0.94 33 -1,900 µg/L
2016 Lead 0.0432 0.041 0.93 0.12 - 11 µg/L
2016 Lithium 0.0510 0.330 0.84 0.99 - 73 µg/L
2016 Manganese 0.0453 0.396 1.00 6.0 - 1,800 µg/L
2016 Mercury 0.1382 0.000 0.76 0.01 - 0.05 µg/L
2016 Molybdenum 0.0540 0.046 0.95 0.33 - 46 µg/L
2016 Nickel 0.0491 0.160 0.87 0.40 - 19 µg/L
2016 Selenium 0.1078 0.137 0.43 0.38 - 3.1 µg/L
2016 Silica 0.0486 0 n/a 4.7 - 270 mg/L
2016 Silver 0.0657 0.087 0.43 0.05 - 4.4 µg/L
2016 Strontium 0.0474 0 n/a 21 - 410 µg/L
2016 Thallium 0.0475 0.025 0.88 0.48 - 5.0 µg/L
2016 Uranium 0.0510 -0.003 0.79 0.37 - 1.9 µg/L
2016 Vanadium 0.0552 0.160 0.84 0.19 - 28 µg/L
2016 Zinc 0.0633 0.029 1.00 6.2 - 1,100 µg/L
Major Ions
Fiscal Yr Constituent Slope 1) Y-intercept0)   r2 Range used
2016 Bromide 0.0466 0.033 0.47 0.07 - 1.4 mg/L
2016 Calcium 0.0414 0 n/a 0.13 - 55 mg/L
2016 Chloride 0.0272 0.080 0.95 0.28 - 59 mg/L
2016 Fluoride 0.0454 0.013 0.90 0.04 - 1.8 mg/L
2016 Magnesium 0.0396 0 n/a 0.05 - 24 mg/L
2016 Potassium 0.0384 0.034 0.86 0.08 - 10 mg/L
2016 Potassium (low level) 0.0429 0.012 0.84 0.08 - 1.0 mg/L
2016 Sodium 0.0379 0.000 n/a 0.12 - 50 mg/L
2016 Sulfate 0.0287 0.12252 0.99 0.19 - 178 mg/L
Physical Properties
Fiscal Yr Constituent Slope 1) Y-intercept0)   r2 Range used
2016 Acid Neutralizing Capacity 0.0262 0.571 0.77 24 - 85 mg/L
2016 Alkalinity 0.0262 0.571 0.77 24 - 85 mg/L
2016 ROE (105 deg C) 0 10.40 n/a 58 - 410 mg/L
2016 ROE (180 deg C) 0 10.40 n/a 58 - 410 mg/L
2016 Specific Conductance 0.0183 1.354 0.84 4.8 - 640 µS/cm
Nutrients
Fiscal Yr Constituent Slope 1) Y-intercept0)   r2 Range used
2015 NH4 0.0462 0.005 0.75 0.07 - 1.2 mg/L
2015 NH4 + Org N 0.0629 0.046 0.52 0.1 - 1.3 mg/L
2015 NH4 + NO2 + NO3 + Org N 0.0378 0.028 0.67 0.3 - 2.3 mg/L
2015 NO2 + NO3 0.0325 0.003 0.91 0.09 - 1.4 mg/L
2015 NO2 + NO3 (low level) 0.0347 0.002 0.93 0.09 - 1.0 mg/L
2015 Orthophosphate 0.0317 0.001 0.90 0.04 - 1.5 mg/L
2015 Phosphorus 0.0310 0.004 0.85 0.04 - 1.5 mg/L
2015 Phosphorus (low level) 0.0375 0.001 0.57 0.04 - 0.2 mg/L
Trace Metals and Silica
Fiscal Yr Constituent Slope 1) Y-intercept0)   r2 Range used
2015 Aluminum 0.0611 0.881 0.90 16 - 320 µg/L
2015 Antimony 0.0419 0.024 0.89 0.06 - 5.0 µg/L
2015 Arsenic 0.0624 0.020 0.99 0.20 - 24 µg/L
2015 Barium 0.0311 0.293 0.76 6.8 - 72 µg/L
2015 Beryllium 0.0427 0.019 0.37 0.09 - 0.75 µg/L
2015 Boron 0.0472 1.615 0.45 4.6 - 69 µg/L
2015 Cadmium 0.0353 0.017 0.90 0.02 - 3.9 µg/L
2015 Chromium 0.0396 0.094 0.70 0.35 - 5.6 µg/L
2015 Cobalt 0.0462 0.013 0.96 0.09 - 5.6 µg/L
2015 Copper 0.0578 0.061 0.98 0.9 - 21 µg/L
2015 Iron 0.0460 2.926 0.94 33 -1,900 µg/L
2015 Lead 0.0432 0.041 0.93 0.12 - 11 µg/L
2015 Lithium 0.0510 0.330 0.84 0.99 - 73 µg/L
2015 Manganese 0.0453 0.396 1.00 6.0 - 1,800 µg/L
2015 Mercury 0.1382 0.000 0.76 0.01 - 0.05 µg/L
2015 Molybdenum 0.0540 0.046 0.95 0.33 - 46 µg/L
2015 Nickel 0.0491 0.160 0.87 0.40 - 19 µg/L
2015 Selenium 0.1078 0.137 0.43 0.38 - 3.1 µg/L
2015 Silica 0.0486 0 n/a 4.7 - 270 mg/L
2015 Silver 0.0657 0.087 0.43 0.05 - 4.4 µg/L
2015 Strontium 0.0474 0 n/a 21 - 410 µg/L
2015 Thallium 0.0475 0.025 0.88 0.48 - 5.0 µg/L
2015 Uranium 0.0510 -0.003 0.79 0.37 - 1.9 µg/L
2015 Vanadium 0.0552 0.160 0.84 0.19 - 28 µg/L
2015 Zinc 0.0633 0.029 1.00 6.2 - 1,100 µg/L
Major Ions
Fiscal Yr Constituent Slope 1) Y-intercept0)   r2 Range used
2015 Bromide 0.0466 0.033 0.47 0.07 - 1.4 mg/L
2015 Calcium 0.0414 0 n/a 0.13 - 55 mg/L
2015 Chloride 0.0272 0.080 0.95 0.28 - 59 mg/L
2015 Fluoride 0.0454 0.013 0.90 0.04 - 1.8 mg/L
2015 Magnesium 0.0396 0 n/a 0.05 - 24 mg/L
2015 Potassium 0.0384 0.034 0.86 0.08 - 10 mg/L
2015 Potassium (low level) 0.0429 0.012 0.84 0.08 - 1.0 mg/L
2015 Sodium 0.0379 0.000 n/a 0.12 - 50 mg/L
2015 Sulfate 0.0287 0.12252 0.99 0.19 - 178 mg/L
Physical Properties
Fiscal Yr Constituent Slope 1) Y-intercept0)   r2 Range used
2015 Acid Neutralizing Capacity 0.0262 0.571 0.77 24 - 85 mg/L
2015 Alkalinity 0.0262 0.571 0.77 24 - 85 mg/L
2015 ROE (105 deg C) 0 10.40 n/a 58 - 410 mg/L
2015 ROE (180 deg C) 0 10.40 n/a 58 - 410 mg/L
2015 Specific Conductance 0.0183 1.354 0.84 4.8 - 640 µS/cm
Nutrients
Fiscal Yr Constituent Slope 1) Y-intercept0)   r2 Range used
2014 NH4 0.0462 0.005 0.75 0.07 - 1.2 mg/L
2014 NH4 + Org N 0.0629 0.046 0.52 0.1 - 1.3 mg/L
2014 NH4 + NO2 + NO3 + Org N 0.0378 0.028 0.67 0.3 - 2.3 mg/L
2014 NO2 + NO3 0.0325 0.003 0.91 0.09 - 1.4 mg/L
2014 NO2 + NO3 (low level) 0.0347 0.002 0.93 0.09 - 1.0 mg/L
2014 Orthophosphate 0.0317 0.001 0.90 0.04 - 1.5 mg/L
2014 Phosphorus 0.0310 0.004 0.85 0.04 - 1.5 mg/L
2014 Phosphorus (low level) 0.0375 0.001 0.57 0.04 - 0.2 mg/L
Trace Metals and Silica
Fiscal Yr Constituent Slope 1) Y-intercept0)   r2 Range used
2014 Aluminum 0.0611 0.881 0.90 16 - 320 µg/L
2014 Antimony 0.0419 0.024 0.89 0.06 - 5.0 µg/L
2014 Arsenic 0.0624 0.020 0.99 0.20 - 24 µg/L
2014 Barium 0.0311 0.293 0.76 6.8 - 72 µg/L
2014 Beryllium 0.0427 0.019 0.37 0.09 - 0.75 µg/L
2014 Boron 0.0472 1.615 0.45 4.6 - 69 µg/L
2014 Cadmium 0.0353 0.017 0.90 0.02 - 3.9 µg/L
2014 Chromium 0.0396 0.094 0.70 0.35 - 5.6 µg/L
2014 Cobalt 0.0462 0.013 0.96 0.09 - 5.6 µg/L
2014 Copper 0.0578 0.061 0.98 0.9 - 21 µg/L
2014 Iron 0.0460 2.926 0.94 33 -1,900 µg/L
2014 Lead 0.0432 0.041 0.93 0.12 - 11 µg/L
2014 Lithium 0.0510 0.330 0.84 0.99 - 73 µg/L
2014 Manganese 0.0453 0.396 1.00 6.0 - 1,800 µg/L
2014 Mercury 0.1382 0.000 0.76 0.01 - 0.05 µg/L
2014 Molybdenum 0.0540 0.046 0.95 0.33 - 46 µg/L
2014 Nickel 0.0491 0.160 0.87 0.40 - 19 µg/L
2014 Selenium 0.1078 0.137 0.43 0.38 - 3.1 µg/L
2014 Silica 0.0486 0 n/a 4.7 - 270 mg/L
2014 Silver 0.0657 0.087 0.43 0.05 - 4.4 µg/L
2014 Strontium 0.0474 0 n/a 21 - 410 µg/L
2014 Thallium 0.0475 0.025 0.88 0.48 - 5.0 µg/L
2014 Uranium 0.0510 -0.003 0.79 0.37 - 1.9 µg/L
2014 Vanadium 0.0552 0.160 0.84 0.19 - 28 µg/L
2014 Zinc 0.0633 0.029 1.00 6.2 - 1,100 µg/L
Major Ions
Fiscal Yr Constituent Slope 1) Y-intercept0)   r2 Range used
2014 Bromide 0.0466 0.033 0.47 0.07 - 1.4 mg/L
2014 Calcium 0.0414 0 n/a 0.13 - 55 mg/L
2014 Chloride 0.0272 0.080 0.95 0.28 - 59 mg/L
2014 Fluoride 0.0454 0.013 0.90 0.04 - 1.8 mg/L
2014 Magnesium 0.0396 0 n/a 0.05 - 24 mg/L
2014 Potassium 0.0384 0.034 0.86 0.08 - 10 mg/L
2014 Potassium (low level) 0.0429 0.012 0.84 0.08 - 1.0 mg/L
2014 Sodium 0.0379 0.000 n/a 0.12 - 50 mg/L
2014 Sulfate 0.0287 0.12252 0.99 0.19 - 178 mg/L
Physical Properties
Fiscal Yr Constituent Slope 1) Y-intercept0)   r2 Range used
2014 Acid Neutralizing Capacity 0.0262 0.571 0.77 24 - 85 mg/L
2014 Alkalinity 0.0262 0.571 0.77 24 - 85 mg/L
2014 ROE (105 deg C) 0 10.40 n/a 58 - 410 mg/L
2014 ROE (180 deg C) 0 10.40 n/a 58 - 410 mg/L
2014 Specific Conductance 0.0183 1.354 0.84 4.8 - 640 µS/cm
Nutrients
Fiscal Yr Constituent Slope 1) Y-intercept0)   r2 Range used
2013 NH4 0.0462 0.005 0.75 0.07 - 1.2 mg/L
2013 NH4 + Org N 0.0629 0.046 0.52 0.1 - 1.3 mg/L
2013 NH4 + NO2 + NO3 + Org N 0.0378 0.028 0.67 0.3 - 2.3 mg/L
2013 NO2 + NO3 0.0325 0.003 0.91 0.09 - 1.4 mg/L
2013 NO2 + NO3 (low level) 0.0347 0.002 0.93 0.09 - 1.0 mg/L
2013 Orthophosphate 0.0317 0.001 0.90 0.04 - 1.5 mg/L
2013 Phosphorus 0.0310 0.004 0.85 0.04 - 1.5 mg/L
2013 Phosphorus (low level) 0.0375 0.001 0.57 0.04 - 0.2 mg/L
Trace Metals and Silica
Fiscal Yr Constituent Slope 1) Y-intercept0)   r2 Range used
2013 Aluminum 0.0611 0.881 0.90 16 - 320 µg/L
2013 Antimony 0.0419 0.024 0.89 0.06 - 5.0 µg/L
2013 Arsenic 0.0624 0.020 0.99 0.20 - 24 µg/L
2013 Barium 0.0311 0.293 0.76 6.8 - 72 µg/L
2013 Beryllium 0.0427 0.019 0.37 0.09 - 0.75 µg/L
2013 Boron 0.0472 1.615 0.45 4.6 - 69 µg/L
2013 Cadmium 0.0353 0.017 0.90 0.02 - 3.9 µg/L
2013 Chromium 0.0396 0.094 0.70 0.35 - 5.6 µg/L
2013 Cobalt 0.0462 0.013 0.96 0.09 - 5.6 µg/L
2013 Copper 0.0578 0.061 0.98 0.9 - 21 µg/L
2013 Iron 0.0460 2.926 0.94 33 -1,900 µg/L
2013 Lead 0.0432 0.041 0.93 0.12 - 11 µg/L
2013 Lithium 0.0510 0.330 0.84 0.99 - 73 µg/L
2013 Manganese 0.0453 0.396 1.00 6.0 - 1,800 µg/L
2013 Mercury 0.1382 0.000 0.76 0.01 - 0.05 µg/L
2013 Molybdenum 0.0540 0.046 0.95 0.33 - 46 µg/L
2013 Nickel 0.0491 0.160 0.87 0.40 - 19 µg/L
2013 Selenium 0.1078 0.137 0.43 0.38 - 3.1 µg/L
2013 Silica 0.0486 0 n/a 4.7 - 270 mg/L
2013 Silver 0.0657 0.087 0.43 0.05 - 4.4 µg/L
2013 Strontium 0.0474 0 n/a 21 - 410 µg/L
2013 Thallium 0.0475 0.025 0.88 0.48 - 5.0 µg/L
2013 Uranium 0.0510 -0.003 0.79 0.37 - 1.9 µg/L
2013 Vanadium 0.0552 0.160 0.84 0.19 - 28 µg/L
2013 Zinc 0.0633 0.029 1.00 6.2 - 1,100 µg/L
Major Ions
Fiscal Yr Constituent Slope 1) Y-intercept0)   r2 Range used
2013 Bromide 0.0466 0.033 0.47 0.07 - 1.4 mg/L
2013 Calcium 0.0414 0 n/a 0.13 - 55 mg/L
2013 Chloride 0.0272 0.080 0.95 0.28 - 59 mg/L
2013 Fluoride 0.0454 0.013 0.90 0.04 - 1.8 mg/L
2013 Magnesium 0.0396 0 n/a 0.05 - 24 mg/L
2013 Potassium 0.0384 0.034 0.86 0.08 - 10 mg/L
2013 Potassium (low level) 0.0429 0.012 0.84 0.08 - 1.0 mg/L
2013 Sodium 0.0379 0.000 n/a 0.12 - 50 mg/L
2013 Sulfate 0.0287 0.12252 0.99 0.19 - 178 mg/L
Physical Properties
Fiscal Yr Constituent Slope 1) Y-intercept0)   r2 Range used
2013 Acid Neutralizing Capacity 0.0262 0.571 0.77 24 - 85 mg/L
2013 Alkalinity 0.0262 0.571 0.77 24 - 85 mg/L
2013 ROE (105 deg C) 0 10.40 n/a 58 - 410 mg/L
2013 ROE (180 deg C) 0 10.40 n/a 58 - 410 mg/L
2013 Specific Conductance 0.0183 1.354 0.84 4.8 - 640 µS/cm
Nutrients
Fiscal Yr Constituent Slope 1) Y-intercept0)   r2 Range used
2012 NH4 0.0462 0.005 0.75 0.07 - 1.2 mg/L
2012 NH4 + Org N 0.0629 0.046 0.52 0.1 - 1.3 mg/L
2012 NH4 + NO2 + NO3 + Org N 0.0378 0.028 0.67 0.3 - 2.3 mg/L
2012 NO2 + NO3 0.0325 0.003 0.91 0.09 - 1.4 mg/L
2012 NO2 + NO3 (low level) 0.0347 0.002 0.93 0.09 - 1.0 mg/L
2012 Orthophosphate 0.0317 0.001 0.90 0.04 - 1.5 mg/L
2012 Phosphorus 0.0310 0.004 0.85 0.04 - 1.5 mg/L
2012 Phosphorus (low level) 0.0375 0.001 0.57 0.04 - 0.2 mg/L
Trace Metals and Silica
Fiscal Yr Constituent Slope 1) Y-intercept0)   r2 Range used
2012 Aluminum 0.0611 0.881 0.90 16 - 320 ug/L
2012 Antimony 0.0556 0.546 0.52 3 - 33 ug/L
2012 Arsenic 0.0624 0.020 0.99  
2012 Barium 0.0311 0.293 0.76  
2012 Beryllium 0.0490 0.272 0.50 8 -26 ug/L
2012 Boron 0.0472 1.615 0.45  
2012 Cadmium 0.0596 0.116 0.90 2 - 27 ug/L
2012 Chromium 0.0396 0.094 0.70 0.4 - 5.6 u/L
2012 Cobalt 0.0462 0.013 0.96  
2012 Copper 0.0578 0.061 0.98 0.9 - 21 ug/L
2012 Iron 0.0460 2.926 0.94  
2012 Lead 0.0432 0.041 0.93  
2012 Lithium 0.0562 0.757 0.81 1 - 54 ug/L
2012 Manganese 0.0453 0.396 1.00  
2012 Mercury 0.1382 0.000 0.76 0.01 - 0.07 u/L
2012 Molybdenum 0.0540 0.046 0.95  
2012 Nickel 0.0491 0.160 0.87  
2012 Selenium 0.1078 0.137 0.43  
2012 Silica 0.0486 0 n/a  
2012 Silver 0.0657 0.087 0.43 0.05 - 4.4 ug/L
2012 Strontium 0.0474 0 n/a  
2012 Thallium 0.0475 0.025 0.88  
2012 Uranium 0.0510 -0.003 0.79  
2012 Vanadium 0.0552 0.160 0.84  
2012 Zinc 0.0633 0.029 1.00 6.2 - 1,100 ug/L
Major Ions
Fiscal Yr Constituent Slope 1) Y-intercept0)   r2 Range used
2012 Bromide 0.0466 0.033 0.47 0.07 - 1.4 mg/L
2012 Calcium 0.0414 0 n/a 0.13 - 55 mg/L
2012 Chloride 0.0272 0.080 0.95 0.28 - 59 mg/L
2012 Chloride (low level) 0.0439 0.009 0.64 0.28 - 4.4 mg/L
2012 Fluoride 0.0454 0.013 0.90 0.04 - 1.8 mg/L
2012 Magnesium 0.0396 0 n/a 0.05 - 24 mg/L
2012 Potassium 0.0384 0.034 0.86 0.08 - 10 mg/L
2012 Potassium (low level) 0.0429 0.012 0.84 0.08 - 1.0 mg/L
2012 Sodium 0.0379 0.000 n/a 0.12 - 50 mg/L
2012 Sulfate 0.0287 0.12252 0.99 0.19 - 178 mg/L
2012 Sulfate (low level) 0.0537 0.026 0.94 0.19 - 2.0 mg/L
Physical Properties
Fiscal Yr Constituent Slope 1) Y-intercept =0)   r2 Range used
2012 Alkalinity 0.0262 0.571 0.77  
2012 ROE (105 deg C) 0 10.40 n/a  
2012 ROE (180 deg C) 0 10.40 n/a  
2012 Specific Conductance 0.0183 1.354 0.84  
Fiscal Yr Constituent Slope = b1 Y-Inter = bo r-Squared Range used
2011 Alkalinity 0.0173 1.56 0.805 0.1 - 180
2011 Aluminum 0.0871 3.6 0.475 10.3 - 70.6
2011 Antimony 0.0556 0.546 0.521 3 - 33
2011 Arsenic 0.0561 0.418 0.8 0.2 - 33
2011 Barium 0.0417 0.411 0.932 10 - 185
2011 Beryllium 0.049 0.272 0.5 8 - 26
2011 Boron 0.0514 2.92 0.702 10 - 280
2011 Cadmium 0.0596 0.116 0.897 0.067 - 0.928
2011 Calcium 0.0429 0 n/a 0.1 - 75
2011 Chloride 0.0272 0.4245 0.874 0.1 - 142
2011 Chromium 0.048 0.493 0.832 7 - 49
2011 Cobalt 0.0413 0.397 0.434 1 - 27
2011 Copper 0.0434 0.731 0.682 1 - 38
2011 ROE (DSRD 180) 0 12.64 n/a 50 - 750
2011 Fluoride 0.0582 0.0178 0.913 0.02 - 2.2
2011 Iron 0 6.46 n/a 5 - 100
2011 Lead 0.0533 0.514 0.808 4 - 46
2011 Lithium 0.0562 0.757 0.809 1 - 54
2011 Magnesium 0.0399 0 n/a 0.1 - 26
2011 Manganese 0.0408 0.611 0.902 1 - 98
2011 Molybdenum 0.0423 0.918 0.47 1 - 78
2011 Nickel 0.0483 0.781 0.567 1 - 33
2011 Potassium 0.0547 0.035 0.907 0.1 - 10.2
2011 Selenium 0.0828 0.5403 0.654 2 - 10.2
2011 Silica 0.0605 0 n/a 1 - 24
2011 Silver 0.0518 0.412 0.725 2 - 20
2011 Sodium 0.0423 0 n/a 0.1 - 154
2011 Strontium 0.043 0 n/a 10 - 680
2011 Sulfate 0.0361 0.358 0.971 0.1 - 240
2011 Thallium 0.0731 0.511 0.751 3 - 51
2011 Uranium 0.097 -0.029 0.389 1.1 - 4
2011 Vanadium 0 1.633 n/a 3 - 35
2011 Zinc 0.0494 1.27 0.767 3 - 73
2011 Mercury 0.08 0 n/a 0.015 - 0.100
2011 Bromide 0 0.0415 n/a  
2011 Chloride 0 0.1873 n/a 0.2 - 3
2011 Fluoride 0 0.0246 n/a 0.025 - 0.35
2011 Potassium 0.0664 0.0153 0.76 0.10 - 1.0
2011 Sulfate 0.0000 0.247 n/a 0.3 - 3.0
2011 Specific Conductance 0.01825 1.354 0.84  
2011 Ammonia 0.0512 0.010 0.90 0.04 - 1.4
2011 NH3 + Org N 0.0667 0.0596 0.539 0.05 - 2.5
2011 NO2 + NO3 0.0554 0.000 n/a 0.036 - 1.75
2011 NO2 + NO3 (low level) 0.0583 0 n/a 0.036 - 1.0
2011 Orthophosphate 0.0467 0.000 n/a 0.038 - 1.6
2011 Phosphorus 0.0367 0.00434 0.939 0.04 - 1.6
2011 Phosphorus (low level) 0.0689 0.000 n/a 0.04 - 0.2
Fiscal Yr Constituent Slope = b1 Y-Inter = bo r-Squared Range used
2010 Alkalinity 0.0173 1.56 0.805 0.1 - 180
2010 Aluminum 0.0871 3.6 0.475 10.3 - 70.6
2010 Antimony 0.0556 0.546 0.521 3 - 33
2010 Arsenic 0.0561 0.418 0.8 0.2 - 33
2010 Barium 0.0417 0.411 0.932 10 - 185
2010 Beryllium 0.049 0.272 0.5 8 - 26
2010 Boron 0.0514 2.92 0.702 10 - 280
2010 Cadmium 0.0596 0.116 0.897 0.067 - 0.928
2010 Calcium 0.0429 0 n/a 0.1 - 75
2010 Chloride 0.0272 0.4245 0.874 0.1 - 142
2010 Chromium 0.048 0.493 0.832 7 - 49
2010 Cobalt 0.0413 0.397 0.434 1 - 27
2010 Copper 0.0434 0.731 0.682 1 - 38
2010 ROE (DSRD 180) 0 12.64 n/a 50 - 750
2010 Fluoride 0.0582 0.0178 0.913 0.02 - 2.2
2010 Iron 0 6.46 n/a 5 - 100
2010 Lead 0.0533 0.514 0.808 4 - 46
2010 Lithium 0.0562 0.757 0.809 1 - 54
2010 Magnesium 0.0399 0 n/a 0.1 - 26
2010 Manganese 0.0408 0.611 0.902 1 - 98
2010 Molybdenum 0.0423 0.918 0.47 1 - 78
2010 Nickel 0.0483 0.781 0.567 1 - 33
2010 Potassium 0.0547 0.035 0.907 0.1 - 10.2
2010 Selenium 0.0828 0.5403 0.654 2 - 10.2
2010 Silica 0.0605 0 n/a 1 - 24
2010 Silver 0.0518 0.412 0.725 2 - 20
2010 Sodium 0.0423 0 n/a 0.1 - 154
2010 Strontium 0.043 0 n/a 10 - 680
2010 Sulfate 0.0361 0.358 0.971 0.1 - 240
2010 Thallium 0.0731 0.511 0.751 3 - 51
2010 Uranium 0.097 -0.029 0.389 1.1 - 4
2010 Vanadium 0 1.633 n/a 3 - 35
2010 Zinc 0.0494 1.27 0.767 3 - 73
2010 Mercury 0.08 0 n/a 0.015 - 0.100
2010 Chloride 0 0.1873 n/a 0.2 - 3
2010 Fluoride 0 0.0246 n/a 0.025 - 0.35
2010 Potassium 0.0664 0.0153 0.76 0.10 - 1.0
2010 Sulfate 0 0.2473 n/a 0.3 - 3.0
2010 Specific Conductance 0.0183 1.354 0.84  
2010 Ammonia 0.0512 0.0102 0.901 0.04 - 1.4
2010 NH3 + Org N 0.0667 0.060 0.54 0.05 - 2.5
2010 NO2 + NO3 0.0554 0 n/a 0.036 - 1.75
2010 NO2 + NO3 (low level) 0.0583 0.000 n/a 0.036 - 1.0
2010 Orthophosphate 0.0467 0 n/a 0.038 - 1.6
2010 Phosphorus 0.0367 0.004 0.94 0.04 - 1.6
2010 Phosphorus (low level) 0.0689 0 n/a 0.04 - 0.2
Fiscal Yr Constituent Slope = b1 Y-Inter = bo r-Squared Range used
2009 Alkalinity 0.0173 1.56 0.805 0.1 - 180
2009 Aluminum 0.0871 3.6 0.475 10.3 - 70.6
2009 Antimony 0.0556 0.546 0.521 3 - 33
2009 Arsenic 0.0561 0.418 0.8 0.2 - 33
2009 Barium 0.0417 0.411 0.932 10 - 185
2009 Beryllium 0.049 0.272 0.5 8 - 26
2009 Boron 0.0514 2.92 0.702 10 - 280
2009 Cadmium 0.0596 0.116 0.897 0.067 - 0.928
2009 Calcium 0.0429 0 n/a 0.1 - 75
2009 Chloride 0.0272 0.4245 0.874 0.1 - 142
2009 Chromium 0.048 0.493 0.832 7 - 49
2009 Cobalt 0.0413 0.397 0.434 1 - 27
2009 Copper 0.0434 0.731 0.682 1 - 38
2009 ROE (DSRD 180) 0 12.64 n/a 50 - 750
2009 Fluoride 0.0582 0.0178 0.913 0.02 - 2.2
2009 Iron 0 6.46 n/a 5 - 100
2009 Lead 0.0533 0.514 0.808 4 - 46
2009 Lithium 0.0562 0.757 0.809 1 - 54
2009 Magnesium 0.0399 0 n/a 0.1 - 26
2009 Manganese 0.0408 0.611 0.902 1 - 98
2009 Molybdenum 0.0423 0.918 0.47 1 - 78
2009 Nickel 0.0483 0.781 0.567 1 - 33
2009 Potassium 0.0547 0.035 0.907 0.1 - 10.2
2009 Selenium 0.0828 0.5403 0.654 2 - 10.2
2009 Silica 0.0605 0 n/a 1 - 24
2009 Silver 0.0518 0.412 0.725 2 - 20
2009 Sodium 0.0423 0 n/a 0.1 - 154
2009 Strontium 0.043 0 n/a 10 - 680
2009 Sulfate 0.0361 0.358 0.971 0.1 - 240
2009 Thallium 0.0731 0.511 0.751 3 - 51
2009 Uranium 0.097 -0.029 0.389 1.1 - 4
2009 Vanadium 0 1.633 n/a 3 - 35
2009 Zinc 0.0494 1.27 0.767 3 - 73
2009 Mercury 0.08 0 n/a 0.015 - 0.100
2009 Chloride 0 0.1873 n/a 0.2 - 3
2009 Fluoride 0 0.0246 n/a 0.025 - 0.35
2009 Potassium 0.0664 0.0153 0.76 0.10 - 1.0
2009 Sulfate 0 0.2473 n/a 0.3 - 3.0
2009 Specific Conductance 0.0183 1.354 0.84  
2009 Ammonia 0.0512 0.0102 0.901 0.04 - 1.4
2009 NH3 + Org N 0.0667 0.0596 0.539 0.05 - 2.5
2009 NO2 + NO3 0.0554 0 n/a 0.036 - 1.75
2009 NO2 + NO3 (low-level) 0.0583 0 n/a 0.036 - 1.0
2009 Orthophosphate 0.0467 0 n/a 0.038 - 1.6
2009 Orthophosphate (low-level) 0 0.00678 n/a 0.038 - 0.2
2009 Phosphorus 0.0367 0.00434 0.939 0.04 - 1.6
2009 Phosphorus (low-level) 0.0689 0 n/a 0.04 - 0.2
Fiscal Yr Constituent Slope = b1 Y-Inter = bo r-Squared Range used
2008 Alkalinity 0.0173 1.56 0.805 0.1 - 180
2008 Aluminum 0.0871 3.6 0.475 10.3 - 70.6
2008 Antimony 0.0556 0.546 0.521 3 - 33
2008 Arsenic 0.0561 0.418 0.8 0.2 - 33
2008 Barium 0.0417 0.411 0.932 10 - 185
2008 Beryllium 0.049 0.272 0.5 8 - 26
2008 Boron 0.0514 2.92 0.702 10 - 280
2008 Cadmium 0.0596 0.116 0.897 0.067 - 0.928
2008 Calcium 0.0429 0 n/a 0.1 - 75
2008 Chloride 0.0272 0.4245 0.874 0.1 - 142
2008 Chromium 0.048 0.493 0.832 7 - 49
2008 Cobalt 0.0413 0.397 0.434 1 - 27
2008 Copper 0.0434 0.731 0.682 1 - 38
2008 ROE (DSRD 180) 0 12.64 n/a 50 - 750
2008 Fluoride 0.0582 0.0178 0.913 0.02 - 2.2
2008 Iron 0 6.46 n/a 5 - 100
2008 Lead 0.0533 0.514 0.808 4 - 46
2008 Lithium 0.0562 0.809 1 - 54
2008 Magnesium 0.0399 0 n/a 0.1 - 26
2008 Manganese 0.0408 0.611 0.902 1 - 98
2008 Molybdenum 0.0423 0.918 0.47 1 - 78
2008 Nickel 0.0483 0.781 0.567 1 - 33
2008 Potassium 0.0547 0.035 0.907 0.1 - 10.2
2008 Selenium 0.0828 0.5403 0.654 2 - 10.2
2008 Silica 0.0605 0 n/a 1 - 24
2008 Silver 0.0518 0.412 0.725 2 - 20
2008 Sodium 0.0423 0 n/a 0.1 - 154
2008 Strontium 0.043 0 n/a 10 - 680
2008 Sulfate 0.0361 0.358 0.971 0.1 - 240
2008 Thallium 0.0731 0.511 0.751 3 - 51
2008 Uranium 0.097 -0.029 0.389 1.1 - 4
2008 Vanadium 0 1.633 n/a 3 - 35
2008 Zinc 0.0494 1.27 0.767 3 - 73
2008 Mercury 0.08 0 n/a 0.015 - 0.100
2008 Chloride 0 0.1873 n/a 0.2 - 3
2008 Fluoride 0 0.0246 n/a 0.025 - 0.35
2008 Potassium 0.0664 0.0153 0.76 0.10 - 1.0
2008 Sulfate 0 0.2473 n/a 0.3 - 3.0
2008 Ammonia 0.0512 0.0102 0.901 0.04 - 1.4
2008 NH3 + Org N 0.0667 0.0596 0.539 0.05 - 2.5
2008 NO2 + NO3 0.0554 0 n/a 0.036 - 1.75
2008 NO2 + NO3 0.0583 0 n/a 0.036 - 1.0
2008 Orthophosphate 0.0467 0 n/a 0.038 - 1.6
2008 Orthophosphate 0 0.00678 n/a 0.038 - 0.2
2008 Phosphorus 0.0367 0.00434 0.939 0.04 - 1.6
2008 Phosphorus 0.0689 0 n/a 0.04 - 0.2

 

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