Llys-y-frân is a small village and parish in the community of New Moat on the southern slopes of the Preseli Mountains in Pembrokeshire, Wales.

Llys-y-frân was originally a chapelry; in the 16th century it was controlled by various landowners in the district, but it does appear (Llisvrayne) as a parish on a 1578 map.

[11][12] The dam is 100 feet (30 m) high and the lake is fed by the River Syfynwy (or Syfni) that also feeds Rosebush Reservoir a few miles upstream to the northeast.

[13] In 2008, a refurbished hydro-electric scheme was completed, raising the power output to an average of 26 kW; the original turbine generated considerably less.

[14] In 2017 Welsh Water announced a £4 million investment to enhance the park's facilities, to be completed in 2019,[15][16] but in 2019 the project was put on hold when the construction company went into administration.

[17] A new construction company was appointed, with work scheduled to be completed in 2020, until which time the park and reservoir would remain closed.

[20] The reservoir is an important fishery in South West Wales, and has hosted national and international fishing competitions.