Site

Nitrate Level (mg/L)

Spring

Fall

Mississippi River, Clinton, IA

0.55

1.20

Mississippi River, Memphis, TN

1.60

2.90

Rio Grande River, El Paso, TX

0.38

0.59

Ohio River, Benwood, WV

0.87

1.30

Willamette River, Portland, OR

0.28

0.98

Missouri River, Garrison Dam, ND

0.40

0.14

Hudson River, Poughkeepsie, NY

0.49

0.64

Platte River, Sharpes Station, MO

1.90

1.30