NcVirginian... I live in Southern Oregon, near the Rogue River. There have been two dams recently removed here. The first was Savage Rapids dam a litle above the city of Grants Pass. It's removal allowed unfettered passage by salmon and steelhead. It used to have a very difficult and treacherous fish ladder which, so some say, killed lots of anadronomous fish. some of the troubles they've had there include, drifting gravel, moving sand and gravel bars, and a very dangerous rapid which has some ancient debris in it, like cable and other man-caused debris. The drifting gravel has clogged the inflow to some major irrigation and water supply pumps that serve a part of the Grant's Pass population with drinking water. This was (some say) unforseen. However, the gravel bar that reappeared was clearly visible in some very old photos of the river prior to the dam's construction.
The other dam was Gold Ray Dam a few miles above the town of Gold Hill, Oregon. It created a large sluggish backwater known as Kelly Slough. Removal of that dam was completed sometime last year, and it drained a vast area which had become a perennial wetland supporting a unique ecosystem. The first spring after removal was a disaster in terms of the mosquitos. they were breeding in the mud, and pools left behind. The folks living above the old damsite were nearly run out of their homes for a time by the skeeters. Many of those folks have well and water troubles as a result of the change in the water table level.
My unbiased view is this... The results of dam removal are many and varied beyond the obvious and even the not so obvious. No one can accurately predict the whole "after" picture. There will be benefits, and detriments.
The Rogue river is now unimpeded to anadronomous fish for much of it's length, but there is still Lost Creek Dam, much farther upstream, built in the early 1980's. It has no ladder, and stops fish migration there. The river is by no means unimpeded. and Lost Creek Dam controls the flow of the river completely, and therefore the fish runs. Water releases can and do control the temperature of the river completely. As for a lower dam, the temperature control would be more limited, as the depth of the water above the dam is what determines how cool the wateris that cn be released. Applegate Dam, on the Applegate River, a major tributary of the Rogue, was also built in the early 1980's It is quite a deep reservoir, and dropped the temperature of the Applegate to the point that nearly noone swims in it any more, it's so cold, even in the heat of the summer.
The Klamath River, just south of us here, has a series of hydropower dams on it that are now embroiled in a huge dispute regarding their removal. Fish are the main factor on the pro-removal side. Water storage for farming and the economy it supports is on the other side.

There is no easy, certain answer in any case of a dam's construction or removal. Botttom line, in my opinion is it's a crap shoot.
Check the websites for the Medford, Oregon Mail Tribune newspaper for archived articles on Savage Rapids Dam Removal, and Gold Ray Dam Removal. Also The Grant's Pass, Oregon Daily Courier, and the Rogue River Press, of City of Rogue River, Oregon.
For info on the Klamath River situation, there is the Herald and News of Klamath Falls, Oregon. Also the Federal Bureau of Reclamation has info on the Klamath River and Klamath Basin water situation on their website. The Klamath thing has been a war with the farmers there for maybe 15 years..
I hope Iv'e not just rambled here, brother. Check out some of the sources I mentioned to see the history of the ongoing debate before and after dam removal. The Gold Ray Dam debacle is the most recent, and the most interesting, I think. Home and property owners above the old damsite are feeling profound effects, and have a slew of lawsuits in progress. The whole issue of dams is a firestorm, and is fueled by enotion as much as fact in most cases.
.................................................. Modoc Dan