Reserva natural del Pilar, Nature reserve at Rio Lujan floodplains, Buenos Aires Province, Argentina

Reserva natural del Pilar is a nature reserve along the floodplain of the Río Luján, in Buenos Aires Province, Argentina, spread across three separate areas. It consists of lagoons, wetlands, and native vegetation growing along the riverbank.

The reserve was created by a local ordinance in 1991, then received broader legal protection through a decree in 2003. These two steps show a growing local effort to protect this river landscape over time.

The reserve takes its name from the Pilar district, and its wetland plants include the sarandí colorado, a shrub declared a municipal natural monument on 26 May 2006. The reserve is managed by the Asociación para la Protección del Patrimonio Natural del Partido del Pilar, a public-interest NGO recognised since 10 February 2004. A nursery a few kilometres away propagates native species from northeastern Buenos Aires for reintroduction here.

The reserve is reached via Provincial Route 25 from the city of Pilar. Opening hours change depending on the season, so it is worth checking before you go.

The site has a nursery that grows native plants specifically to replant them in areas where they have disappeared from the region. This work takes place on the grounds and can be seen by visitors walking through the reserve.