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3. Top and Bottom Release Dams

What are (if any) the benefits to top release dams compared to bottom release dams for a trout stream below the contraption? I have in mind a particular stream that has a series of three or four small lakes; all which hold wild trout. The dams backing these lakes up release water over the top of the dam in a 'spill-way' fashion. Are there any benefits to this?

Jess,

I think research has shown that both can be problematic. Bottom release dams contribute colder water to streams otherwise to warm to hold trout but can also add higher concentrations of metals and other compounds (due to settling) and dangerous levels of poisons produced from the anaerobic breakdown of organic matter in the lake's low-oxygen depths. Top releases are more natural, acting like giant pools adding plankton to the food chain, but also contribute warmer water to the watershed that causes severe thermal stress for native species. So, I guess it's pick your poison.

I definitely have recognized those two points and its a tough, pick your own poison situation i guess. Is there a better one in your opinion though, if it was totally personal?

I would go with the top release because that would be more natural. Think about beaver dams, log jams, fallen trees. It is not optimum, but as long as the temperature range isn't to wide, fish can usually adjust to their surroundings quite well.
I also think the temperature of the pools would depend on how fast the water is coming into the pools.

Some good points Samuel i like it!

I'm sorry to burst the bubble, but top release dams were conceived (and their subsequent impact) on an entirely different scale than beaver dams or pools. Small ones with little thermal impact are not economically worth the trouble. Though I have personally benefited from many years of tremendous fishing on tailwaters (usually the bottom release type), their quality is already waning and even what they offered at the time wasn't worth the destruction of the anadromous runs. My personal opinion is dismantle them all. I won't see the resurrection of our fisheries on these waters, but perhaps you two will.

Good or bad there are a couple of bottom releases dams in my area that have yielded great trout fishing over many years. I hope you're wrong about the waning quality of them.
Bruce

Have you heard about the removal of the Elwha and Glines Canyon Dams on the Elwha River... MAGNIFICENT!

I hope so too, Bruce. I probably overstated the problem due to lamenting the destruction of our once great steelhead and salmon runs. As far as trout go, many have improved and seem to be holding their own. The Lower Sac, Upper Missouri and Delaware come to mind as good examples. Jason is the guy that could really weigh in on this.

When I was comparing the two kinds, the size of dams I had in mind were small dams, but as Entoman said the thermal impact that it would have would probably increase with size.

Yeah Jason what are your thoughts on this!?

Jason lets hear it..?

I fish both of these rivers. Both the EB and WB of the Delaware and the main stem. The two branches have very large earthen dams with concrete spillways. Both are very deep - in the 200' range. Both the EB & WB have bottom releases. The water coming out now into the WB is 42 degrees - I checked the temp on Thursday. Five miles down river, in the afternoon, it seldom gets to be more than 55 degrees if there is a release of at least 500 cfs. In the mornings, in front of my cabin, which is about twelve miles below the release point the water temp at 6:00 is usually no more than 52 degrees, in July, with a 500 cfs release.

The upper East Branch is a much smaller river with a much diminished release because NYC believes the water in Pepacton Reservoir (which empties into the EB) has the best potable water. The release regimen during the summer can often be no more than 130 cfs. Yet the river remains cool enough to provide very good to excellent fishing in the late afternoons and evenings.

The Missouri below Holter Dam (a much lower dam than that on the branches of the Delaware) still provides relatively cool water and has made what was once the home to whitefish and squawfish a world class trout river with great hatches and trout bigger than I wish to discuss openly. Even in July and August when the flow on the Missouri drops to around 3000 cfs and the day air temperatures are in the mid 90's, and the water temps are approaching the low 70's, the river continues to provide very good morning and evening fishing. During the heat of the day both the trout hole up in deeper, cooler, water and the fishermen should follow suit and give the fish a break.

Wbranch,

Not to start an argument, but out of curiosity is it possible for you to take a heavy metal or toxin test on that river?

"Not to start an argument, but out of curiosity is it possible for you to take a heavy metal or toxin test on that river?"

No, I'm a fly fisherman, not a freaking chemist! Where in the world did that inquiry come from?

If you are interested maybe you can find some data at this web site. I do know that natural gas drilling, fracking, is planned for many areas in the counties surrounding the river. Little drilling has actually been started due to moratoriums being put in place by NY and PA.

http://www.americanrivers.org/our-work/protecting-rivers/endangered-rivers/2010-endangered-upper-delaware.html

So Matt, are you saying that bottom release dams provide better trout habitat in your opinion? And if so, what do you think about the opposing top release style dams?

Jesse wrote;

"So Matt, are you saying that bottom release dams provide better trout habitat in your opinion? And if so, what do you think about the opposing top release style dams?"

Well in my narrow field of experience I have found far better trout fishing resulting at bottom release dams compared to over the top releases. My experience is limited to the Big Horn and Missouri in MT and the East and West branches of the Delaware in the northeast. Whatever positive effects the main stem gets are resultants of the inflow from those two branches.

The coldwater releases from those two NYC reservoirs have created a viable, and sustainable, wild trout fishery in the main stem of the Delaware as far south as Calicoon, NY which is about fifty miles south of Cannonsville reservoir and over sixty miles south of Pepacton reservoir. Before the reservoirs were built the entire system had marginal trout reproduction on the two branches and smallmouth were the most targeted sport fish.

I definitely agree with you there buddy. I was just on the Missouri about two weeks ago and it fished great. All the times ive fished it have been great. The Big Horn, West and East Branches of the Delaware are amazing as well. Also, living in the southeast most my life, i know all about the effectiveness of bottom release dams (for areas where trout wouldn't be abundant without them). Good stuff.

Wbranch,

Entoman in his first post on this subject said how bottom release dams can cause heavy metal and other toxin build-up due to settling. That is where I got my question.

Sorry about not clarifying,

Sam

P.S. Thanks for the link.