reflect a variety of geographical and environmental conditions. (e) Uses of grants Amounts from grants received under this section may be used for engineering, design, construction, and final testing of alternative water source projects designed to meet critical water supply needs. Such amounts may not be used for planning, feasibility studies, operation, maintenance, replacement, repair, or rehabilitation. (f) Cost sharing The Federal share of the eligible costs of an alternative water source project carried out using assistance made available under this section shall not exceed 50 percent. (g) Reports On or before September 30, 2023, the Administrator shall transmit to Congress a report on the results of the program established under this section, including progress made toward meeting the critical water supply needs of the participants in the program. (h) Definitions In this section, the following definitions apply: (1) Alternative water source project The term alternative water source project means a project designed to provide municipal, industrial, and agricultural water supplies in an environmentally sustainable manner by conserving, managing, reclaiming, or reusing water, wastewater, or stormwater, or by treating wastewater or stormwater. Such term does not include water treatment or distribution facilities. (2) Critical water supply needs The term critical water supply needs means existing or reasonably anticipated future water supply needs that cannot be met by existing water supplies, as identified in a comprehensive statewide or regional water supply plan or assessment projected over a planning period of at least 20 years. (i) Authorization of appropriations There is authorized to be appropriated to carry out this section a total of $375,000,000 beginning in fiscal year 2019. Such sums shall remain available until expended. .