CA Gov't Code Section 66478.5

(a)

No local agency shall approve either a tentative or a final map of any proposed subdivision to be fronted upon a public waterway, river, or stream which does not provide for a dedication of a public easement along a portion of the bank of the river or stream bordering or lying within the proposed subdivision.

(b)

The extent, width and character of the public easement shall be reasonably defined to achieve reasonable public use of the public waterway, river, or stream consistent with public safety. The reasonableness and extent of the easement shall be determined by the local agency in which the proposed subdivision is to be located. In making the determination for reasonably defining the extent, width, and character of the public easement, the local agency shall consider all of the following:

(1)

That the easement may be for a foot trail, bicycle trail, or horse trail.

(2)

The size of the subdivision.

(3)

The type of riverbank and the various appropriate recreational, educational and scientific uses including, but not limited to, swimming, diving, boating, fishing, water skiing, scientific collection and teaching.

(4)

The likelihood of trespass on private property and reasonable means of avoiding these trespasses.