наблюдаться... (помогите с переводом, пож-та)

[Lidia P.]

Сгустки нефти наблюдались вдоль правого берега реки на протяжении 400 метров.

[Ашот Степанян]

opt-n:
be apparent/appear

[Bernie]

There was crude along the right riverside for the 400 meters.

[Аристарх]

were found

[PERPETRATOR™]

...were observed on a 400m stretch [of water] along the left bank of the river.

[%&$]

Option:
Oil sludges were reported to be located along the left river bank along a 400 m stretch.

[%&$]

on a 400m stretch +1

[askandy]

on a 400m stretch +2
along the left river bank - 1

+ 400m stretch demonstrated cгустки нефти

[D-50]

(floating) tar balls/oil clots were observed

[Lidia P.]

Всем большое спасибо! )