Water Resources / Environmental Resource Material

I purchased the 2nd edition "6 minute solutions..." for the water resources and environmental depth. When going through the questions, I'm noticing that a lot of the problems cannot be solved using the "Water Resources and Environmental Depth Reference Manual" alone. Are these questions more in depth than needed? Should I focus my studying on just the questions that pertain to the Depth reference manual and skip the rest? Any advice would be greatly appreciated!

The PE Exam is not limited to one reference book. Part of passing this exam is acquiring the correct references.

For the WRE exam, I found 6 minute solutions to be much more in depth than needed. Check ncees' exam outline and stick to those topics. If you're still not sure what to study, I suggest taking a review course.

To be completely honest with you, I didn't find the WR Depth Manual (from PPI) to be all that great. My 2nd time taking the exam, it didnt even make the cut of references. As mentioned, you're not limited to how many resources you can have, but fumbling through multiple resources will cost you a lot of time during the exam. 

I'd say find an old NCEES practice test and try the depth with that manual. That may be a good indication of if you need more books, or just more time getting familiar with that reference.

If you're taking WRE Depth, I'd still recommend understanding every problem in the 6 Minute Solutions book.  Sure, some problems are more in-depth than the actual PE exam, but you'll come away learning and being more prepared.  I wouldn't make this recommendation for any of the other civil sub-disciplines if you're not taking the depth portion of the exam in that sub-discipline.