3. Summary of Survey Results

(1) State of Compliance with EQSs for Human health Items
The state of compliance with EQSs for human health items in FY 2006 is given in Table 2. The overall compliance rate for the 26 items surveyed was 99.3% (compared with 99.1% for the previous year), confirming that most monitoring points met the required EQSs. When evaluating the results for fluorine and boron, monitoring points in seawater areas and monitoring points in rivers, lakes and reservoirs strongly affected by seawater (and therefore with values exceeding EQSs) were not included.

Values exceeding EQSs were observed for five items (lead, arsenic, 1,2-dichloroethane, nitrate-nitrogen, nitrite-nitrogen, and fluorine). In most cases, such as arsenic and fluorine, these high values were derived from natural causes. Other potential causes included effluents from business establishments and a closed/abandoned mine. However, in some monitoring points, the potential cause still remains unknown.

(2) State of Compliance with EQSs for Living Environment Items
1) State of Compliance with EQSs for BOD or COD
i) State of Compliance
Out of the 3,334 specified water bodies by type in Japan (2,563 rivers, 180 lakes/reservoirs, and 591 seawater areas), 2,877 water bodies (2,337 rivers, 100 lakes/reservoirs, and 440 seawater areas) met EQSs for BOD in rivers or COD in lakes/reservoirs and seawater areas (both of which are representative water quality indices for organic pollution), resulting in an overall compliance rate of 86.3% (compared to 83.4% for the previous year). This compliance rate can be further classified according to water body group category, as follows: 91.2% for rivers (compared to 87.2% for the previous year); 55.6% for lakes and reservoirs (53.4% ditto); and 74.5% for seawater areas (76.0% ditto) (Table 3-1).
Among seawater areas, compliance rates for Tokyo Bay, Ise Bay, and the Seto Inland Sea are 68.4% for Tokyo Bay (compared to 63.2% for the previous year), 43.8% for Ise Bay (50.0% ditto), 66.7% for Osaka Bay (66.7% ditto), and 70.7% for the Seto Inland Sea, excluding Osaka Bay (74.0% ditto) (Table 3-2 & Fig. 1-2).
Out of the 10 designated lakes and reservoirs which were designated under the “Law Concerning Special Measures for Conservation of Lake Water Quality” (enacted in July 1984), none of them met the EQSs (Table 7 & Fig. 4).

ii) Changes in Compliance Rate (Table 4, Fig. 1-1 & Fig. 1-2)
Compliance rates with EQSs for BOD or COD in overall public water areas have gradually risen over time (except for FY 1994 and FY 2005 when compliance rates for rivers fell due to the effects of drought), reaching 86.3% in 2006 (the highest record ever). Compliance rates with EQSs for BOD in rivers have also shown a consistent upward trend, reaching 91.2% in 2006 (the highest record ever).
In the case of lakes and reservoirs, compliance rates with EQSs for COD still remain at a low level, even though the rate increased to 55.6% in 2006 (compared to 53.4% for the previous year).
Compliance rates with EQSs for COD in seawater areas have remained at almost the same level in recent years (74.5% in 2006) while the compliance rate for three representative enclosed seawater areas (Tokyo Bay, Ise Bay, and Osaka Bay) has been dropping below 70%.

ⅲ) Changes in Concentration (Table 5 & Fig. 2-1)
The Changes in concentrations of BOD or COD in rivers since 1979 have progressively decreased from, although they were at a level of approximately 3 mg/L twenty years ago to, continued to decrease year by year and reached 1.4 mg/L in 2006. For lakes and reservoirs, changes in BOD or COD concentrations have remained almost flat constant in recent years at nearly the higher part of 3 mg/L but, from FY 2003 to FY 2006, they dropped to nearly 3 mg/L. The concentration of BOD or COD in seawater areas varies between 1.8 and 1.9 mg/L.

2) Total Nitrogen and Total Phosphorus
i) State of Compliance with EQSs for Total Nitrogen and Total Phosphorus in Lakes and Reservoirs (Table 8-1, Table 8-2 & Fig. 5)
The guideline values for EQSs for total nitrogen and total phosphorus in lakes and reservoirs were set in 1982 and compliance has been monitored since 1984. Currently, 109 water areas are designated as a specified water body by type for total nitrogen and total phosphorus. Of these, 50 water areas have met the EQSs, resulting in a compliance rate of 45.9% (compared to 46.6% for the previous year). For total nitrogen, out of 35 specified water bodies by type, three water areas have met the EQSs, resulting in a compliance rate of 8.6% (compared to 11.4% for the previous year). For total phosphorus, out of 109 specified water bodies by type, 57 water areas have met the EQSs, resulting in a compliance rate of 52.3% (compared to 52.4% for the previous year).

ii) Changes in Concentration of Total Nitrogen and Total Phosphorus in Lakes and Reservoirs (Table 9, Fig. 6-1, Fig. 6-2, Table 10, Fig. 7-1 & Fig. 7-2)
Compared with the compliance rates shown above, there have been almost no changes in the concentration of total nitrogen and total phosphorus in lakes and reservoirs, overall.

iii) State of Compliance with EQSs for Total Nitrogen and Total Phosphorus in Seawater Areas (Table 11-1, Table 11-2 & Fig. 8)
A total of 152 seawater areas are being designated as specified water bodies by type, with regard to total nitrogen and total phosphorus. Of these, 122 water areas have met the EQSs, resulting in a compliance rate of 80.3% (compared to 82.2% for the previous year). (EQSs for both total nitrogen and total phosphorus shall have to be applied to seawater areas in combination with each other).

Iv) Changes in Concentration of Total Nitrogen and Total Phosphorus in Seawater Areas (Table 13, Fig. 10-1 & Fig. 10-2)
There has basically been no change in the concentration of total nitrogen and total phosphorus in seawater areas since 1998 when the overall number of specified water bodies by type exceeded 100.

(3) Total Zinc
Water quality surveys for total zinc were performed at 4,825 points in response to the addition of total zinc to the list of EQSs for aquatic life conservation.
The distribution of total zinc concentration is shown in Fig. 12. This Figure shows that, if the results are compared with EQS values for each water body group, 95% of monitoring points in rivers have a lower value than the 0.03 mg/L EQS value, all monitoring points in lakes and reservoirs have a lower value than the 0.03 mg/L EQS value and, for seawater areas, 96% of monitoring points have a lower value than the 0.02 mg/L EQS value for general sea areas and 89% of monitoring points have a lower value than the 0.01 mg/L EQS value for special areas.
In addition, for EQSs for aquatic life conservation, the classification of specified water bodies by type (including rivers and lakes/reservoirs) was applied for the first time to the nine water bodies of four water systems, including the Kitakami River, the Tama River, the Yamato River and the Yoshino River, in June 2006. As shown in Appendix Table 6, all monitoring points in these water areas have a lower value than the 0.03 mg/L EQS value for rivers and lakes/reservoirs.

(4) Trihalomethane Formation Potential (THM-FP)
The distribution of THM-FP concentration is shown in Fig. 13-1. This Figure shows that approximately 70% of all monitoring points have THM-FP values of 0.05 mg/L or lower. As shown in Fig. 13-2, the average value (of all monitoring points) continues to be nearly constant between 0.04 and 0.05 mg/L.

(5) Monitoring Substances (Items to be Monitored)
Table 16-1 shows the FY 2006 state of monitoring substances for human health items exceeding guideline values. The FY 2006 survey was performed at 1,968 points. The items exceeding guideline values were as follows: antimony, vinyl chloride monomer, epichlorohydrin, and 1,4-dioxane in rivers; total manganese in rivers and lakes/reservoirs; and uranium in rivers and seawater areas. No other items exceeded guideline values.
The distribution of concentrations of monitoring substances for living environment items (regarding aquatic life conservation) is given in Fig. 14. The survey was performed at 1,098 points. In this case, hardly any samples exceeded guideline values even though each item was compared to the minimum guideline value on a type basis.

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