NSF WQI Dissolved oxygen (%
saturation)
Values extracted from the
quality graphic elaborated
for each parameter
a
0.17
NSWFQI
3
ð Þ
¼
P n
i¼1
WiIi
P
Wi
0–25
¼ very bad
26–50
¼ bad
51–70
¼ regular
71–90
¼ good
91–100
¼ excellent
Fecal coliforms
b
0.16
(1b/100 ml)
pH
0.11
BOD5 (mg/L)
0.11
Nitrates (mg/L)
0.10
Phosphates (mg/L)
0.10
Temperature (_C)
0.10
Turbidity (NTU)
0.08
Total solids (mg/L)
0.07
CCME
WQI
No specific parameters
defined.
F1: Scope (% of variables
that do not meet their
objectives at least once)
–
CCME WQI
¼ 100‐
ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi
F
2
1 þ F
2
2 þ F
2
3
q
1:732
0
@
1
A
0–44
¼ poor
45–64
¼ marinal
65–79
¼ regular
80–94
¼ good
95–100
¼ excellent
It is a
flexible index
used with several different parameters.
F2: Frequency (% of
individual tests that do
not meet their objectives)
For each parameter, a
maximum and a minimum water quality
objective need to be
F3: amplitude (amount by
which failed tests do not
meet their objectives)
** sub-indices F1, F2 and
F3
a
Graphics for each of the parameters are available on the http://www.water-research.net/watrqualindex/waterqualityindex.htm web page.
b
Fecal coliforms is not a parameter usually obtained from the automated sampling networks. However, this is not a problem, since some of the variables can be
omitted in calculating the NSF WQI.
3 Surface Water Quality and Analysis
85