Fukushima Diary reports and translates:
"Gunma local government announced they measured 17 Bq/kg of Iodine 131 from the sewage sludge of a water purifying plant. They also measured 44 ~ 68 Bq/kg of cesium from 6 plants too. The samples were taken from 12/6 ~ 12/14."
Majia here: Iodine-131 has an eight day half life and is therefore evidence of recent fission.