div class=ts-pagebuttonPage 1button div class=ts-image amp-img class=ts-thumb alt=Page 1: Colorado Parks and Wildlife24 AMERICAN ANGLER The layer of gravel and cobble beneath the stream bottom is called the hyporheic zone Many mayflies stoneflies and caddisfies spend src=https:reader035vdocumentinreader035viewer20220712186051d55fe5e2e571704a71c3html5thumbnails1jpg width=142 height=106 layout=responsive amp-img divdivdiv class=ts-pagebuttonPage 2button div class=ts-image amp-img class=ts-thumb alt=Page 2: Colorado Parks and Wildlife24 AMERICAN ANGLER The layer of gravel and cobble beneath the stream bottom is called the hyporheic zone Many mayflies stoneflies and caddisfies spend src=https:reader035vdocumentinreader035viewer20220712186051d55fe5e2e571704a71c3html5thumbnails2jpg width=142 height=106 layout=responsive amp-img divdivdiv class=ts-pagebuttonPage 3button div class=ts-image amp-img class=ts-thumb alt=Page 3: Colorado Parks and Wildlife24 AMERICAN ANGLER The layer of gravel and cobble beneath the stream bottom is called the hyporheic zone Many mayflies stoneflies and caddisfies spend src=https:reader035vdocumentinreader035viewer20220712186051d55fe5e2e571704a71c3html5thumbnails3jpg width=142 height=106 layout=responsive amp-img divdiv