I highly recommend the water resources depth class at Engineering Education and Training (EET). I just passed in April. It was my first attempt and I was also studying for the surveying and seismic. I do not have a background in the environmental stuff, so I was really worried about this portion, but I felt very prepared after the EET course and was confident that I had passed after sitting for the exam.
The notebook that the instructor has put together is worth paying for the class in itself. He includes cheat sheets for commonly used equations (which was excellent and a great resource during the exam), review/lecture notes, background information, reference tables, and more practice problems then you'll ever need. It's a small class so you get lots of individual attention.
I only studied materials from this class and felt strongly that it was all I needed to prepare for the exam. It was a great way to keep my studies organized and to not feel overwhelmed by all the other books, study guides, and classes out there.
Class is offered in Sacramento, CA or remotely via a webinar. I believe they are also offering an on demand webinar.
http://www.eet-california.com/civil_pe_class_info/live_seminar
(Scroll to the bottom for information on the water resources depth class)
Their breadth class (for the morning part) was also very helpful.