Table 1 Model parameters that contribute to the OEHI

Temperature (°C)

18 - 24

12 - 31

$\{\begin{array}{l}\begin{array}{cc}\hfill g\left(v,18,5\right)\hfill & \hfill v<18\hfill \end{array}\\ \begin{array}{cc}\hfill 1\hfill & \hfill 18\le v\le 24\hfill \end{array}\\ \begin{array}{cc}\hfill g\left(v,24,2\right)\hfill & \hfill v>24\hfill \end{array}\end{array}$

pH

6.5 - 8

2 - 10

$\{\begin{array}{l}\begin{array}{cc}\hfill g\left(v,6.5,1.3\right)\hfill & \hfill v<6.5\hfill \end{array}\\ \begin{array}{cc}\hfill 1\hfill & \hfill 6.5\le v\le 8\hfill \end{array}\\ \begin{array}{cc}\hfill g\left(v,8,1.3\right)\hfill & \hfill v>8\hfill \end{array}\end{array}$

Dissolved Oxygen (%)

90 - 110

0 -140

$\{\begin{array}{cc}\hfill g\left(v,100,38\right)\hfill & \hfill v<100\hfill \\ \hfill g\left(v,100,60\right)\hfill & \hfill v\ge 100\hfill \end{array}$

NTOT: Total Nitrogen (μg/L)

0 - 350

100 - 1000

$\{\begin{array}{l}\begin{array}{cc}\hfill g\left(v,5,1.6\right)\hfill & \hfill v<5\hfill \end{array}\\ \begin{array}{cc}\hfill 1\hfill & \hfill 5\le v\le 350\hfill \end{array}\\ \begin{array}{cc}\hfill g\left(v,350,300\right)\hfill & \hfill v>350\hfill \end{array}\end{array}$

NOx: NO₂ + NO₃ (μg/L)

0 - 10

0 - 150

$\{\begin{array}{l}\begin{array}{cc}\hfill g\left(v,1,0.3\right)\hfill & \hfill v<1\hfill \end{array}\\ \begin{array}{cc}\hfill 1\hfill & \hfill 1\le v\le 20\hfill \end{array}\\ \begin{array}{cc}\hfill g\left(v,20,26\right)\hfill & \hfill v>20\hfill \end{array}\end{array}$

NH₃: Toxic Ammonia (μg/L)

0 - 10

0 - 90

$\{\begin{array}{l}\begin{array}{cc}\hfill 1\hfill & \hfill v\le 10\hfill \end{array}\\ \begin{array}{cc}\hfill g\left(v,10,9\right)\hfill & \hfill v>10\hfill \end{array}\end{array}$

Total Phosphorus (μg/L)

0 - 10

0 - 150

$\{\begin{array}{l}\begin{array}{cc}\hfill g\left(v,1,0.3\right)\hfill & \hfill v<1\hfill \end{array}\\ \begin{array}{cc}\hfill 1\hfill & \hfill 1\le v\le 20\hfill \end{array}\\ \begin{array}{cc}\hfill g\left(v,20,26\right)\hfill & \hfill v>20\hfill \end{array}\end{array}$

Filtered Reactive Phosphate (PO₄) (μg/L)

0 - 5

0 - 100

$\{\begin{array}{l}\begin{array}{cc}\hfill g\left(v,1,0.3\right)\hfill & \hfill v<1\hfill \end{array}\\ \begin{array}{cc}\hfill 1\hfill & \hfill 1\le v\le 15\hfill \end{array}\\ \begin{array}{cc}\hfill g\left(v,15,26\right)\hfill & \hfill v>15\hfill \end{array}\end{array}$

Chlorophyll-a (Chl-a) (μg/L)

0 - 5

0 - 70

$\{\begin{array}{l}\begin{array}{cc}\hfill 1\hfill & \hfill v\le 8\hfill \end{array}\\ \begin{array}{cc}\hfill g\left(v,8,18\right)\hfill & \hfill v>8\hfill \end{array}\end{array}$

EC: Electrical Conductivity (μS/cm)

Not Specific

0 - 200

$\{\begin{array}{l}\begin{array}{cc}\hfill 1\hfill & \hfill v\le 100\hfill \end{array}\\ \begin{array}{cc}\hfill g\left(v,100,300\right)\hfill & \hfill v>100\hfill \end{array}\end{array}$

TSS: Total Suspended Solids (mg/L)

Not Specific

0 - 150

$\{\begin{array}{l}\begin{array}{cc}\hfill 1\hfill & \hfill v\le 20\hfill \end{array}\\ \begin{array}{cc}\hfill g\left(v,20,25\right)\hfill & \hfill v>20\hfill \end{array}\end{array}$

Turbidity (NTU)

Not Specific

0 - 200

$\{\begin{array}{l}\begin{array}{cc}\hfill 1\hfill & \hfill v\le 20\hfill \end{array}\\ \begin{array}{cc}\hfill g\left(v,20,34\right)\hfill & \hfill v>20\hfill \end{array}\end{array}$

Macroinvertebrates (Signal2, SWAMPS)

N/A

3 - 5

$\frac{v-1}{9}$

Flora (Native, Non-weed)

N/A

0.3 – 0.5

Equal to the Native and Non-weed ratios as defined in text.