The reserve sits at the juncture where the Rio Verde meets the Parana River, in the municipality of Brasilandia, 388 kilometers from Campo Grande and just 14 kilometers from Brasilandia town. It contains a tangled system of lagoons, streams, and channels connected to the Parana main channel - which has migrated eastward over geological time, leaving traces of old beds dating back 10,000 to 40,000 years. Two prehistoric archaeological sites lie within the reserve's boundaries, remnants of human occupation from a period when the Parana ran along different courses and floodplain settlements concentrated along different banks. The climate is hot and humid, with one to three dry months per year. Most of the year, the varzea - seasonally flooded forest - holds standing water in the low places and a rich green mat of aquatic plants above.

The property had a corporate history before it became a reserve. In the 1950s, the Grupo Cisalpina Agricola S/A acquired Fazenda Olimpia, a large cattle and agriculture operation. CESP later acquired both the Cisalpina group and a separate property called Fazenda Florida, combining them into the Cisalpina/Florida Complex. On November 26, 2003, CESP formally described the idea of converting the complex into a private natural heritage reserve. The original proposal covered 6,261 hectares, but only the land above the 259-meter waterline - the level allowed for seasonal reservoir operations - could be legally protected. The Brazilian Institute of Environment and Renewable Natural Resources (IBAMA) began analyzing the request on June 7, 2004. The municipal chamber of Brasilandia approved the reserve on November 16, 2005. Final state creation took until 2016 - more than a decade of administrative process to formalize what had been promised as compensation for the flooded reserves.

The reserve holds at least 95 plant species, 171 bird species, 25 species of terrestrial fauna, and 44 fish species - a significant inventory for land that once grew cattle and rice. Marsh deer wade through the varzea's shallow pools. Maned wolves, Brazil's striking russet-colored canids, hunt the drier cerrado edges. Broad-snouted caimans slide through the lagoon channels. Giant anteaters and southern tamanduas work the flooded grasses for ants. The vegetation carries echoes of an older climate - cactus plants grow in some drier patches, unusual for a marshland but consistent with the cerrado's geological history, when the region was drier than it is now. The diversity comes from the overlay of Quaternary climate shifts, the reserve's variety of moisture zones, and the legacy of previous human occupation.

When the Sergio Motta reservoir filled, the circulation patterns of the entire area changed. Water that had moved through seasonal channels now sat in slower, deeper impoundments. The vegetation began adapting. As of 2012, botanists working in the reserve noted that the plant mix was still shifting - the groundwater table had risen, and cerrado species adapted to drier conditions were giving ground to species that preferred more moisture. What the region had slowly become over the late twentieth century - drier, more cerrado-like - it was now reversing back toward wetland conditions. Restoration programs within the reserve have begun reforesting the more degraded areas and releasing native animals as habitat recovers. The reserve is designated as a future component of the proposed Trinational Biodiversity Corridor, which would link protected areas in Brazil, Paraguay, and Argentina in the Upper Parana ecoregion.

Cisalpina faces pressures that exist across rural Brazilian protected areas. Sanitation in surrounding Brasilandia is inadequate, and untreated sewage flows via the Aviacao and Bom Jardim channels into the reservoir that borders the reserve. The soil and groundwater are contaminated. Environmental crimes - illegal hunting, deforestation in adjacent lands, careless burning - continue to occur, and local awareness of why the reserve matters remains limited. The reserve's boundaries are fenced. Its ownership is legally settled. Its management plan was finalized around the time of the 2016 state decree that formally established it. What it is still doing, more than a decade after creation, is finding its stable state - ecologically, as the vegetation adjusts to new water levels, and socially, as it tries to become part of how the people of Brasilandia think about the landscape around them.