eddie_walker,

Some people like 'em, some don't. Some have trouble with them leaking, some don't.

Reasons to drain....what if someone puts a bad fish in your pond..a drain could help solve that problem. Of course, there are other ways to solve it as well. What if you want to expand and/or renovate the pond. A drain could help with that, but again there are other ways to attack that problem as well. Livestock can be watered without having direct access to pond...but again ways around that too.

My personal opinion is that anything through the dam should be avoided if at all possible...because of the leaking potential.

I've renovated two ponds now and neither one would have benefited from a drain. On one I just knocked a hole in the dam and on the other dug a trench through the spillway. Much less worry than something through the dam...but that's just my opinion.

Look into siphon systems...they have been discussed considerably. Also, a trash pump can be rented or purchased much cheaper than installing a drain through the dam. Admittedly, I am biased on this question. I've seen many posts herein where folks have had to fix ( at significant expense) a through the dam drain.

Hopefully others will give you the other side to help with your decision.