Ministry of the Environment measured 7,100 Bq/Kg of Cs134 and 137 from the ground soil of Shimagawa dam, which is a river-head area to Tokyo.
They monitored 50 locations of river, and 19 locations of lake and river-head area in Gunma and published the result on 1/13/2012.(I-131, Cs-134, Cs-137)
The monitoring was done in early December.
From the result, high level of cesium was measured from the ground soil of the dams in river-head area.
1. Shimagawa Dam : 7,100 Bq/Kq
2. Yagisawa Dam : 2,900 Bq/Kg
3. Haruna lake : 2,500 Bq/Kg
They measured high level of cesium from river too.
1. Sakuragawa : 3,700 Bq/Kg
2. Ogurogawa : 3,100 Bq/Kg
3. Usuigawa : 2,000 Bq/Kg
Water comes from Gunma to Tokyo. Tapwater of Tokyo is likely to be contaminated at least by cesium. If Tokyo local government doesn’t warn the contamination of river, they conceal something.