I know that my students and I were out on March 9, and then the Sunday after March 9 I was on-site as well. Then we went back out on March 17, and on March 17 there was no extraction taking place. I believe the causeway was completely removed by March 17, which is why our pictures show the re-watering of the stream on March 17.
On June 1st, 2006. See this statement in context.