(a) All streams or other bodies of water which appear as black lines with accompanying waters index numbers on the reference maps herein, or which appear as blue continuous or dotted lines to indicate natural waters on the original published maps listed above, and which natural waters are not specifically designated in table I, shall be assigned the same classes and standards of quality and purity as the specifically designated waters to which they are directly tributary.

(b) All streams, rivulets, and other collections of natural surface waters within the basins as above defined, which waters are not shown on the original published maps listed above, shall be assigned to class D with standards of quality and purity for class D assigned thereto; provided, however, that any continuous flowing natural stream which is not shown on the reference maps shall have the same classification and assigned standards as the waters to which it is directly tributary.