Grogarry is one of the famous Machair lochs of South Uist. It lies behind Grogarry Lodge, on the Machair - hence why it is called a Machair loch.
The Machair is a strip of land close to the sea, where the soil consists of a large percentage of crushed shells. Therefore any lochs on this land are alkaline, and have rich feeding for the fish that inhabit them.
The fish are often beautifully marked, and more importantly, tend to grow quite large due to the abundant food supply.
Over quite a few years, I stayed in Grogarry lodge as part of a party of twelve anglers for a week at the end of August. Although we were mainly there for the sea trout fishing, usually a few members of the party would have a go on Grogarry at some point. Although the fishing could be classed as a "bit dour", fish in the 2 to 3lb class were caught most years.