The Aguaí State Biological Reserve is one of the ten state conservation units of the integral protection group of Santa Catarina, with an area of 7,672 hectares, and is considered a special area for environmental preservation, since it shelters one of the richest natural heritages of the country, the Atlantic Forest.

Aguaí (Chrysophyllum viride) is the name of a tree that is present in the Atlantic Forest and in the conservation unit it dominates mainly the tree extract on the steep slopes of Serra Geral. Created in 1983, the Aguaí reserve covers four municipalities: Morro Grande, Nova Veneza, Siderópolis and Treviso.

The conservation unit stands out for presenting a complex natural physiognomy with rugged relief and altitudes that vary from 200 to 1470 meters, with cold waters, typical of mountains and a great diversity and endemism of many species in the various groups of fauna and flora.
For the communities living in the southern region of the state, the conservation unit is essential, because through environmental services it provides water for the Rio São Bento Dam, which supplies the municipalities of Criciúma, Forquilhinha, Maracajá, Içara, Nova Veneza, Turvo and Meleiro.

In the area covered by the reserve there are important springs that form the tributaries of the Araranguá River, the main river of the hydrographic basin of the same name. There are more than 300 springs in the area, with significant environmental value for the region, as they have been little altered by human action.

An indicator of the environmental quality of these waters is the existence of a crab from the time of the giant dinosaurs, popularly known as the river crab or Apancora (Aegla rossiana). The scientific name of this crab, Aegla, comes from Greek and means guardian of springs and fountains.

Beneath the thick lava flows in the Campos de Cima da Serra area, there is an immense underground water reservoir, the Guarani Aquifer system. Aquifers are porous and permeable rocks or sediments, which have pore voids and allow the underground water to move. They can thus store and transmit significant quantities of water, which can be put to various uses.