At the heart of garden is the endangered species island which acts as a rescue center for endangered species.Key among others Encephalartos whitelockii which was previously classified as Vulnerable based on its small extent of occurrence and area of occupancy and occurrence at a single location. At the time, there was no evidence of decline.
However, in May 2007, approval was given for the construction of a hydroelectric plant above the waterfall where the plants occur and construction work began in 2008. The construction has resulted in decline in the population. Although a management plan was developed, the construction and increased access to the site has led to decline which may continue. TBG has taken the initiative to protect this species both in situ and ex situ at the garden and other selected places. This species is listed on Appendix I of the CITES Appendices. Although the gorge falls within the Queen Elizabeth National Park, 90% of the population occurs outside the park.