California Code, Public Utilities Code - PUC § 99313

(a) From the funds made available pursuant to subdivision (c) of Section 99312 and paragraph (2) of subdivision (a) of Section 99312.1, an amount shall be allocated by the Controller to each transportation planning agency and county transportation commission, and the San Diego Metropolitan Transit Development Board based on the ratio of the population of the area under its jurisdiction to the total population of the state.  The Controller shall base these allocations on a report prepared by the Department of Transportation.  On or before June 30 of each year, the Department of Transportation shall prepare and submit to the Controller a report detailing the population of each transportation planning agency and county transportation commission, and the San Diego Metropolitan Transit Development Board.  For the purpose of this report, the Department of Transportation shall use the most recent population estimates of the Department of Finance and the information provided pursuant to subdivision (b).

(b) To assist the Department of Transportation in determining the populations of the San Diego Metropolitan Transit Development Board, the San Diego Association of Governments, the El Dorado County Transportation Commission, the Placer County Transportation Planning Agency, and the Tahoe Regional Planning Agency for the purpose of subdivision (c) of Section 99312 and paragraph (2) of subdivision (a) of Section 99312.1, each of those entities, on or before June 1st of each year, shall provide the department with the population of its respective jurisdiction using the most recent population estimates of the Department of Finance.