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National and prefectural governments control water pollution by setting stringent regulations for wastewater discharge, extension and improvement of sewerage systems, improvement of river water flow, and by appropriate environmental impact assessment of various projects which discharge wastewater into public water areas.
Effluent water quality standards for human health protection (heavy metals, PCB, etc. are ten times more stringent than they are for environmental water quality standards. Effluent water quality is regulated based on its daily maximum value. Violations of effluent water quality standards are easily recognized from monitoring data that exceeds the standards.
National-wide effluent water quality standards for conservation of the living environment suspended solids (SS), etc. are designed to address effluent from household septic tanks. This approach is used because corporations are required to discharge effluent of at least the same quality as that from household septic tanks in the unregulated areas. Standard values for BOD, COD and SS are given as the maximum and average values respectively. Violation of either the maximum or average standard is subject to fine.
As mentioned previously, for public water bodies where the common national minimum effluent standards are insufficient for protecting human health, the prefectural government can set more stringent effluent water quality standards. The following table illustrates the more stringent regulations in Kanagawa and Shiga prefectures and compares them with the common national-wide effluent water quality standards.
Table: More stringent effluent water quality standards by local governments
| Parameters |
Kanagawa Prefecture |
Shiga Prefecture |
National effluent standards |
| “A” area |
“B” area |
Coastal area |
| Lakes with water quality conservation |
Other lakes |
| new |
existing |
new |
existing |
new |
existing |
new |
existing |
new |
existing |
| Health Items |
|
|
|
|
|
|
|
|
|
|
|
| Cd & its compounds |
|
ND |
ND |
0.05 |
|
|
|
|
0.01 |
0.1 |
| CN compounds |
|
0.5 |
|
0.5 |
|
|
|
|
0.1 |
1 |
| Organic phosphorus compounds |
|
ND |
ND |
0.2 |
0.2 |
0.2 |
|
ND |
1 |
| Pd and its compounds |
|
0.05 |
0.05 |
|
|
|
|
|
|
|
0.1 |
| Cr(VI) compounds |
|
0.05 |
0.05 |
|
|
|
|
|
0.05 |
0.5 |
| As & its compounds |
|
0.01 |
0.01 |
|
|
|
|
|
0.05 |
0.1 |
| F and its compounds |
|
0.8 |
0.8 |
|
|
|
|
|
0.05 |
8 river & lake |
| |
|
|
|
|
|
|
|
|
|
|
15 coastal area |
| Living Environmen Items |
|
|
|
|
|
|
|
|
|
|
|
| pH |
|
|
|
|
|
|
|
|
6.0-8.5 |
5.8-8.6 river & lake |
| |
|
|
|
|
|
|
5.8-8.6 |
|
|
|
5.0-9.0 coastal area |
| BOD |
5(3) |
20(15) |
15(10) |
25(20) |
25(20) |
60(50) |
|
|
15-120 |
20-120 |
160(120) |
| COD |
5(3) |
20(15) |
15(10) |
25(20) |
25(20) |
60(50) |
25(20) |
60(50) |
15-120 |
20-120 |
160(120) |
| SS |
15(5) |
50(35) |
35(20) |
70(40) |
70(40) |
90(70) |
70(40) |
90(70) |
60-150 |
60-150 |
200(150) |
| n-Hexane extract (mineral oil) |
3 |
3 |
3 |
|
|
|
|
|
5 |
5 |
| n-Hexane extract (animal fat & vegetable oil) |
3 |
3 |
3 |
5 |
5 |
10 |
5 |
10 |
20 |
30 |
| Phenols |
|
0.005 |
0.005 |
0.05 |
0.5 |
0.5 |
0.5 |
0.5 |
1 |
5 |
| Cu |
1 |
1 |
1 |
1 |
1 |
|
1 |
|
1 |
3 |
| Zn |
1 |
1 |
1 |
1 |
1 |
3 |
1 |
3 |
1 |
5 |
| Dissolved iron |
0.3 |
0.3 |
0.3 |
1 |
3 |
|
3 |
|
10 |
10 |
| Dissolved manganese |
0.3 |
0.3 |
0.3 |
1 |
1 |
1 |
1 |
1 |
10 |
10 |
| Cr |
|
0.1 |
0.1 |
1 |
|
|
|
|
0.1 |
2 |
| Number of coliform group (/cm3 |
(1000) |
|
|
|
|
|
|
|
(3000) |
(3000) |
| Units |
: |
mg/l. |
ND |
: |
Not detectable |
() |
: |
Daily average |
|
