Lake Poorrarecup, also known as Poorarecup Lagoon,[2] is an ephemeral salt lake located in the Great Southern region of Western Australia, approximately 34 km (21 mi) south west of Cranbrook and 65 km (40 mi) north west of Mount Barker.

The remainder drains into a number of smaller seasonal lakes and swamps further downstream with a total area of 3.8 km2 (1.5 sq mi).

The entire area is underlain by sediments of Tertiary or Quaternary age, which overlay Precambrian granites and migmatites.

The low hills in the landscape are often capped with pisolitic laterite, but sandy lunettes, that were once ancient dunes, generally occur parallel to the lake margins.

[4] The area recorded an average annual inflow of 2.65 GL (94,000,000 cu ft) between 1973 and 2001, with approximately 78% of the water evaporating.

Sandy flats support woodlands with a mix of jarrah, marri (Eucalyptus calophylla), wandoo and swamp yate.

The Doris Haynes Memorial Park that surrounds part of the lake was opened in 1975 and the Junior Farmer's Club built a wall in the same year and fishing was permitted.