In Youngblood v. Board of Supervisors (1978) 22 Cal.3d 644, the board of supervisors approved a tentative subdivision map subject to conditions recommended by the planning commission. The general plan for the county changed between the approval of the tentative map and the final map. The final map was not in conformity with the new general plan and it was contended that the board of supervisors' approval of the final map was improper in that the Subdivision Map Act requires that the subdivision map be in conformity with applicable general and specific plans. The Supreme Court in Youngblood concluded that the board of supervisors acted properly in approving the final map as that result was mandated by former Business and Professions Code section 11549.6. The Supreme Court explained the reason for its decision in Youngblood as follows: "The purpose of section 11549.6, as we perceive it, was to confirm that the date when the tentative map comes before the governing body for approval is the crucial date when that body should decide whether to permit the proposed subdivision. Once the tentative map is approved, the developer often must expend substantial sums to comply with the conditions attached to that approval. These expenditures will result in the construction of improvements consistent with the proposed subdivision, but often inconsistent with alternative uses of the land. Consequently it is only fair to the developer and to the public interest to require the governing body to render its discretionary decision whether and upon what conditions to approve the proposed subdivision when it acts on the tentative map. Approval of the final map thus becomes a ministerial act once the appropriate officials certify that it is in substantial compliance with the previously approved tentative map." (22 Cal.3d at pp. 655-656.)