Vatrenus

VATRENUS(Santerno), a river of Gallia Cispadana, one of the southern tributaries of the Padus. It had its sources in the Apennines, flowed under the walls of Forum Cornelii ( Imola), and joined the southern branch of the Padus (the Spineticum Ostium) not far from its mouth, for which reason the port at the entrance of that arm of the river was called the Portus Vatreni. (Plin. Nat. 3.16. s. 20.) The Santernonow flows into the Po di Primaro(the modern representative of the Spinetic branch), above 16 miles from its mouth: but the channels of both are in this part artificial. In this lower part of its course it must always have been more of a canal than a river, whence Martial uses its name as typical of a sluggish stream. (Martial (Mart. 3.67. 2.)
[E.H.B]