The TMT Observatory Corporation board of directors narrowed the list to two sites, one in each hemisphere, for further consideration: Cerro Armazones in Chile's Atacama Desert and Mauna Kea on Hawaii Island. On July 21, 2009, the TMT board announced Mauna Kea as the preferred site. The final TMT site selection decision was based on a combination of scientific, financial, and political criteria. Chile is also where the European Southern Observatory is building the E-ELT. If both next-generation telescopes were in the same hemisphere, there would be many astronomical objects that neither could observe. The telescope was given approval by the state Board of Land and Natural Resources in April 2013. There has been opposition to the building of the telescope, based on potential disruption to the fragile alpine environment of Mauna Kea due to construction, traffic, and noise, which is a concern for the habitat of several species, and because Mauna Kea is a sacred site for the Native Hawaiian culture. The Hawaii Board of Land and Natural Resources conditionally approved the Mauna Kea site for the TMT in February 2011. The approval has been challenged; however, the Board officially approved the site following a hearing on February 12, 2013. Because of the ongoing protests that re-erupted in July 2019, the TMT project officials requested a building permit for a second site choice, the Spanish island of La Palma in the Canary Islands. Rafael Rebolo, the director of the Canary Islands Astrophysics Institute, confirmed that he had received a letter requesting a building permit for the site as a backup in case the Hawaii site cannot be constructed. However, environmentalists in the Canary Islands are gearing up to fight against its construction there as well, citing the loss of archeological and cultural sites.