I thought I hadn't seen TEPCO's press releases on radioactive materials measurements at water intake canals and subdrains at Fukushima I Nuclear Power Plant for some time. It turns out the data has been moved to a separate page "Result of Radioactive Nuclide Analysis around Fukushima Daiichi Nuclear Power Station".
Here are couple of charts from the latest (4/28/2012) data. The cesium densities in the seawater inside the silt screen for Reactor 2 and Reactor 3 have been turning up slightly. For the seawater inside the Reactor 2 silt screen, it could be within the normal fluctuation. The rise in the cesium density in the seawater inside the Reactor 3 silt screen looks rather persistent and sharp, but that could also be within the normal fluctuation in the longer time frame. Note the unit is becquerel/liter.
Seawater inside Reactor 2 silt screen:
Seawater inside Reactor 3 silt screen:
Checking the sub-drain pits, only the Reactor 1 sub-drain and Reactor 2 sub-drain show significant numbers. Here, the unit is becquerel/cubic centimeter.
Reactor 1 sub-drain:
Reactor 2 sub-drain: