Flooding Prevention, Assessment, and Restoration Act of 2023 This bill modifies Department of Agriculture (USDA) watershed programs. The bill modifies the Emergency Watershed Protection (EWP) Program to allow USDA to undertake certain measures that go beyond addressing the immediate impairment of the watershed. Specifically, USDA may undertake measures that increase the level of protection of the watershed if USDA determines that the restoration is in the best interest of the long-term health and the protection of the watershed from repetitive impairments. (The EWP Program assists sponsors, landowners, and operators in implementing emergency recovery measures for runoff retardation and erosion prevention to relieve imminent hazards to life and property created by natural disasters.) In addition, for Watershed Rehabilitation Program (REHAB) projects that serve a limited resource area, the bill increases the federal cost-share to up to 90% of the total rehabilitation costs. Currently, the federal cost-share for all projects is 65% of the total rehabilitation costs. (REHAB assists project sponsors in rehabilitating aging watershed dams that are reaching the end of their design life or no longer meet federal or state safety criteria or performance standards.) USDA must also submit a national agriculture flood vulnerability report to Congress that contains the results of a conservation effects assessment project that studies flood risk on agricultural lands.