I need a ground cover for the storm water retention area beside our house. It is in the corner of our subdivision. The 70' x 100' area fills with water when it rains and slowly drains. It does not hold water, but it is frequently very wet. It is not a pond. Someone suggested Chameleon Houttuynia, but there are so many negative comments about the invasiveness and smell that I am afraid to try it. The County mows the area once or twice a year, so it needs to be able to withstand mowing. Right now we have cattails, thistles and weeds. Mosquitoes are also a problem. The sides are very steep and difficult to mow. We are in north-central Ohio, zone 5b. Any advice?