However, the San Diego Regional Water Quality Control Board withheld its permit approval in December 2000, over concerns that the Sweetwater Reservoir could be polluted in the process. Such an approval was necessary under the Clean Water Act in order to get the necessary approval from the U.S. Army Corps of Engineers (USACE). The suit by Preserve South Bay was dismissed in March 2001, on the grounds that the legislature did not need to review the annexation of state parkland for the highway because it was done under eminent domain. In April, the San Diego Regional Water Quality Control Board approved the project on several conditions, including monitoring the water quality to ensure that the Sweetwater Reservoir would remain a clean water source for local residents. An appeal to the state Water Resources Control Board to overturn the approval was unsuccessful. In July, the USACE approved the wetlands permit for the southern portion of SR 125.