Alma 2:34

and thus he cleared the ground, or rather the bank, which was on the west of the river Sidon, throwing the bodies of the Lamanites which had been slain, into the waters of Sidon, that thereby his people might have room to cross and contend with the Lamanites and the Amlicites, on the west side of the river Sidon.

He cleared the ground on the west side of the river Sidon. He threw the dead Lamanites into the river. This made room for his people to cross and fight the Lamanites and Amlicites on the west side.

He cleared the west bank of the Sidon River, throwing the Lamanite bodies into the water to make room for his people to cross and engage the enemy on the other side.