If it were mine I would connect the two piles as a spread out expansive lengthy area maybe combining rocks, concrete pieces and brush. or tree tops. Note twiggy woody brush will degrade in several years and need to be replaced as i degrades. Install it with plans of replacement. Lots of log type structures are said to be very effective fish habitat. .
See this about Coarse Woody Habitat
https://dnr.wisconsin.gov/sites/default/files/topic/Fishing/Outreach_LitWoodyHabReviewWolter2012.pdf
