Below is a picture taken upstream from Dockholme Bridge of which demonstrates beautifully the importance of scour, oxygen and flow among other benefits. Two years ago we strategically placed boulders instream to seek maximum benefit from the rivers energy, which at the time was gutter like with long flat gravel beds set like concrete. You can notice the weed growth instantly providing cover and habitat for small fry and invertebrates aswell as the natural sortment of clean gravels and depth variation and holding pools behind the boulders. The deep straightened manmade channel has killed nearly all chance of large woody debris and other useful instream features in any amount falling in the river naturally however this picture demonstates that just a few well placed boulders can improve things beyond belief. We don't need millions of pounds just the desire, inclination, training, knowledge and most of all passion to improve things, this pic proves that beyond any doubt.
Whenever I stand on that bridge recently admiring the small effort made, Joe public glance over at the improvements and say "its a lovely river isn't it" and although they probably don't realise our efforts, it just doesn't get much better than that really.