CA Gov't Code Section 65919.8

The referral shall reasonably describe the modification to the proposed action. Any city or county to which the modification is referred shall have 25 days from the date of the referral, or such longer time as the referring county or city specifies or allows at the request of the affected city or county, to review and to comment and to make recommendations on the consistency of the proposed action with applicable general and specific plans and zoning ordinances of the affected city or county. If the affected city or county does not provide the comments and recommendations to the referring county or city within the 25-day period, or such longer time as the referring county or city has specified or allowed at the request of the affected city or county, the board of supervisors or city council may act without considering those comments.

If the affected city or county provides the comments and recommendations prior to the time that the planning commission acts on the proposed action, the planning commission shall also consider the comments and recommendations.

If the planning commission fails to act, the modification may become effective pursuant to Section 65356 or 65857, without consideration of the comments and recommendations.