North Lincolnshire Council has refused to grant planning permission to Lidl to add an extension to the existing store car park in Brigg.
The application also included erection of a trolley bay, relocation and enhancement of a footway with associated landscaping and additional lighting.
Giving its reasons, the local authority said: "The proposal represents a significant encroachment into an Area of Amenity Importance set adjacent to the River Ancholme.
"It is considered that the proposal will have a significant unduly adverse impact on the open character and naturalised appearance of the riverbank setting."
Lidl applied to create 31 car parking spaces on what it described as "undeveloped land."
A report submitted with the planning application said: "Most of the application site itself has been cleared of vegetation over recent years and now comprises tall ruderal vegetation of relatively little amenity value."
Any individual, or company, refused planning permission by a local authority has the right to lodge an appeal with the Government, if it wishes, in an effort to get the decision overturned.