Ysgol Clywedog was created in 2003.

There are 17; Bala Lake, Llyn Celyn, Llyn Brenig, Llyn Trawsfynydd, Llyn Clywedog, Llyn Geirionydd, Llys-y-Fran Reservoir, Elan Valley Reservoirs, Tal-y-Llyn, Lake Vyrnwy, Llyn Padarn, Pontsticill (Merthtyr Tydfil)Reservoir, Llangorse Lake, Llyn Brianne, Rheidol Valley and Llyn Nant y Moch, Llyn Alaw

The SEVERN RIVER catchment is from the west of Newtown in Mid Wales. Firstly is the river Afon Clywedog which is fed from the dam Llyn Clywedog. A large catchment area 360 degrees around Newtown. Then the Severn moves North and collects from catchment areas across Northeast wales above Welshpool, from where its catchment area is added to by tributaries in the West Midlands.
Floodwarn.co.uk have flood information on the river Severn.

it is ' a reservoir'

The major lakes in Wyoming are Yellowstone Lake, Glendo Reservoir, Bighorn Lake, Boysen Reservoir, Flaming Gorge Reservoir, Seminoe Reservoir, Alcova Reservoir, and Keyhole Reservoir.