Valley clogged with leaves. Photo: ŠJohn Leeke.       Not Recommended Losing Connections. This roof valley is clogged with leaves, blocking the connection between the valley and the gutter. It has been a couple of years since it was cleaned out and a tree is beginning to take root in the rotting debris. Flowing water backs up under the shingles and seeps into the woodwork of the cornice beneath the valley. Paint is beginning to peel under the cornice and decay will set in soon. Valley cleaned and maintained. Photo: ŠJohn Leeke. Recommended Re-Connecting. This copper valley is nice and clean. Water easily flows down the valley and into the built-in gutter. Plan your work: Check valleys for proper drainage twice a year. Maintenance tip: Clean out as needed. When cleaning, inspect for holes in the valley flashing.