An "ornamental lake" refers to a man-made body of water in a garden or park that is designed for decorative purposes rather than practical use, such as swimming or boating. Full definition
«Secret garden» bush walk and barbecue areas with ornamental lake. (wikiaustralia.com)
It is the seventeenth century and a wall is being raised around Wychwood, transforming the great house and its park into a private realm of ornamental lakes, grandiose gardens, and majestic avenues designed by Mr. Norris, a visionary landscaper. (bookbrowse.com)
Jump on board a wooden punt and enjoy a serene cruise around the islands dotted throughout this picturesque ornamental lake. (upgradedpoints.com)