Coyrecup Lake is an ephemeral salt lake in Coyrecup, in the Great Southern region of Western Australia located approximately 25 km (16 mi) east of the town of Katanning and about 302 km (188 mi) south east of Perth.

[3][4] The oval shaped lake with an area of 453 ha (1,120 acres)[1] is over a dissected plateau of gneiss and granite bedrock and laterite of the Yilgarn Craton and is part of a floodplain that is a few kilometres wide.

There are Quaternary and Cainozoic alluvial and lacustrine deposits on the valley floors that underlie the lake with variable layers of sand, silt and clay.

The remaining native vegetation is dominated by of proteaceous heath scrub, with many endemic species, although the bulk of the surrounding land has been cleared for cereal cropping.

[3] Inflow to the lake arrives via an approximately 20 km (12 mi) long watercourse that is poorly defined arriving to the lake from the north east and from Little Creek with a length of approximately 15 km (9.3 mi) coming from the south.

Rare flora species known to be found in the nature reserve are Dryandra porrecta and Blennospora phlegmatocarpa.