The river Landistou [fr], a 12.5 km long tributary of the Béez, passes through the village Lys.

Several tributaries of the Landistou (Betbeder, Bonnasserre, Chourrup, Lazerau, Lespereu) also pass through the commune.

[3] The northern part of the commune is drained by the river Luz [fr], a 15.2 km long tributary of the Gave de Pau, and some of its tributaries (Gest, Herran, Luz de Casalis).

[5] The name Lys appears as Lis-Sainte-Colomme (Lily Saint Colomme) from the 1721 census.

[6] The current mayor is Nadège Poueymirou Bouchet, in office since 2020.