41 higher number of class, even this caused by one parameter only. Example; The status of
water from Citarum River, sample taken at Nanjung, October 2004: 1
From one sample, evaluation gave the score -19, therefore conclude as C category heavily polluted.
2 At the same year, with 3 set of data from multiple samples, therefore data have the
range of minimum, maximum and average values, gave the score -83, therefore conclude as D category heavily polluted.
3.11.3.3 Evaluation of Water Quality Status Using Pollution Index Method
Pollution Index use to mention the level of pollution in order of to establish it toward Standard Water Quality BMA. Higher value of pollution index represent more
pollutant in the respective water see Table10.
L
ij
represent the parameter’s concentration according to the Usage of Water
j
, and
C
i
represent water quality parameter
i
, therefore
PI
j
is the Pollution Index for certain usage
j
as the function from
C
i
L
ij.
Every values of
C
i
L
ij
attributing the relative pollution caused by any parameter of water quality. Concentration of DO parameter show the higher pollution when the parameter values
decreased. Theoritical value or maximum value
C
im
saturated DO value. In this case the measured
C
i
L
ij
value are replaced with calculated
C
i
L
ij
value. When standard value
L
ij
are from the range of values, i.e. in pH value, the calculated value
C
i
L
ij
are in use. The equation is shown below:
Plj = √ CiLij
2 M
+ CiLij
2 R
2 ...................................................................................4
42
Table 12. Relation Between Score and Water Quality Status
IP Values
Quality Status Level of Pollution
0 = PIj = 1,0
A Fulfils the requirements
1,0 = PIj = 5,0
B Light pollution
5,0 = PIj = 10
C Polluted
PIj 10
D Heavily polluted
3.11.3.4 Calculation Sample of Pollution Index
Pollution Index Method does not cover the calculation of PI in the situation where Standard Water Quality BMA is zero 0. Whereas the data value is greater than zero, thus
CL value become infinite. Standard Water Quality BMA for Group BCD; oil = 0, the concentration is 0.4 mgl, CL = infinitive, therefore the calculated CL = infinitive, this
make the status become D grade or heavily polluted. Therefore, for Standard Water Quality BMA is zero 0, the best practice is to use
the Detection Limit Method, even this methode is much depend on the analysis procedure and the accuracy of instrumentation. Example; Citarum case at Nanjung , September 2004,
Pollution Index = 7.59, status = C polluted.
3.11.3.5 Water Quality Monitoring
