The situation at Japan's Fukushima Daiichi nuclear plant has been changing rapidly and growing increasingly complex since the earthquake and tsunami hit on March 11. Problems began that day, and each day has brought new, unsettling developments. With unique conditions at each reactor, slightly different responses are required. But the most common response at this point is water. Workers are pumping water into the cores of Units 1, 2 and 3 and adding water to the spent fuel pools at 3, 4, 5 and 6. Each reactor has a used fuel pool in the upper level of their buildings. Getting water to the spent fuel pools at Units 3 and 4 from the air and ground proved difficult for several days after radiation levels spiked. Safety officials say they continue to be most concerned about the pools at Unit 3 and 4. External power had reached most of the units by March 23. Below is a chart showing the status of each of the six reactors, with the most recent information as possible.

UPDATED: The information below reflects developments through 6:33 p.m. EDT March 29. It will continue to be updated as new information becomes available.

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