The Ottawa River at Deep River Ontario is really a 50 mile lake about one mile wide with dam at the upriver end and natural dam at the downriver end.  The Quebec shore for about 35 miles has numerous beautiful sand beaches, free for camping, with springs on some like Oiseau Rock Beach which is also a historic and scenic site with high cliffs which can be hiked up to, or good for low altitude mountaineering.  There are very few cottages on that stretch of the Quebec shore.  There are some old growth pine forests here.  Fishing is good for Pike, Walleye, Bass.  The beaches can be noisy with powerboaters on long weekends so avoid long weekends .. but the scenery is fantastic.