Jiji Press, Feb. 6, 2014: TEPCO Corrects Last Summer’s Water Pollution Data to Record High [...] Samples collected from an observation well close to the sea in early July contained a record 5 million becquerels of strontium-90 per liter of groundwater, the company said. When TEPCO announced the original data that month, the firm said the total amount of radioactive materials emitting beta particles, including strontium-90, was 900,000 becquerels [...] the total amount of beta particle-emitting materials [...] are likely to be around 10 million becquerels, far higher than the previous record high of 3.1 million becquerels for the well.
Kyodo News, Feb. 6, 2014: Record-high strontium-90 in past Fukushima plant groundwater sample — [TEPCO] said Thursday that a groundwater sample taken from a well at the site in July last year contained a record-high 5 million becquerels per liter of radioactive strontium-90.[...] TEPCO official said that “all beta radiation could have been 10 million becquerels in total.”
See also: Highest Yet: Radiation level hits new record in Fukushima groundwater well -- Over 3,000,000 Bq/liter of strontium and beta emitters
Full map and corrected test results here