Weirs and impacts on river life

A lot of attention is paid to the "barrier to migration" effect of weirs - but this misses the vital point that the transportation of riverbed material is also interrupted. Not only that, but holding back large areas of slower water also damages the habitat of a wide range of flora and fauna. Whilst fish passes can be a vital "last resort" that (when they work and are well maintained) may at least allow some wildlife to pass through this degraded habitat; they cannot do anything to improve the habitat itself. The combination of the facts that there is no fish pass as good as "no weir" and that weir removal restores nature's ability to heal itself means that much more needs to be done to explore the potential to modify and remove weirs in part or in their entirety.

[@PhilipJFry-kb5zi]

Having grown up by the Rideau River in Canada, which consists of 45 locks and countless weirs, I see now exactly what sorry habitat I was looking at, without even realizing it.

[@dylancasas485]

Shout Out Dr. Sela 💯💯

[@darrelldarrell8168]

Those weirs and dams also help slow down flood waters and help water infiltrate the aquifers below. It is a matter of establishment. A well established river may benefit from no dams or weirs but you would then need other features for flood control. Trout aren't more important than human development. Streams that go dry need weirs and dams, though, or else there isn't enough flow in the first place to have fish.

[@maximumhardcore4362]

Cool display table

[@TheCommono]

What about streams that don't seem to have that balance of erosion and deposition, are several meters incised, and eventually have reached the rock bed? That act as a huge drainage of the landscape surrounding it? Would it be feasible to reverse the degradation by favoring the deposition of gravel, sand and soil through 'structures' imitating what we see here: 3:17? Maybe we would have to start by reducing the amount of water that goes into the stream because of human activity (agriculture, roads etc.)?

[@UnionCountyPhotography]

I wanna make a table like this!!!!

[@BK-qe6yo]

... Fish ladders