Looking more closely, he sees that the larger river—the one formed by the confluence of the two tributaries—is also to be dammed, but much farther south. This has been dubbed TOJO RIVER . But there is no LAKE TOJO . It appears that this dam will thicken and deepen the Tojo River but not turn it into an actual lake. Goto Dengo infers from this that the valley of the Tojo River must be steep-sided.