And it's not on the eastern edge of Meridiani either. In fact, Meridiani is quite far from the pictured terrain. (Viking 2 landed in Utopia).

Map of Mars

262.30°W
37.68°N

The characteristics of Utopia are not well understood. The surface appears "soft" over a wide area -- which may be due to near surface or surface ice. Craters are commonly filled with unknown material (as in this image) which has eroded in a characteristic fan-shaped pattern, also not well understood.

The "river" in this image is also filled with some unknown material. The crater fill and the "river" fill may be the same material, and may be some sort of icy substance.

Careful observation shows that the "river" is actually an arcing depression that seems to begin at a fault that cuts across the image about a third of the way down the image (in the unprojected jpg version). There is also a broader depression on the other side of the fault, and this one tapers to a point. Rather than being a "river" it looks like this feature is more likely one of the many polygonal cracks in the surface as shown in the context image:

It would be great to know what causes these huge polygons on Mars. Analogous terrain on Earth is an order of magnitude smaller in scale.