SGMA strongly encourages closer planning coordination between water supply and land use agencies to ensure water supply planning accurately forecasts and secures water supplies for future land use changes, and that land use planning considers the effects of projected growth on water resource management. Local agencies are required to acknowledge GSPs or Alternative Plans when a legislative body is adopting or substantially amending its General Plan. General Plans must accurately reflect the information in the GSP with regards to available water supplies. In addition, a city or county must now refer the proposed adoption or substantial amendment of a General Plan to any affected GSA(s). In response, the GSA(s) must provide the land use agency with the current version of its GSP and any information that is relevant to determining the adequacy of existing and planned future water supplies to meet existing and planned future demands.