I have the EPDM buried under the grass for 12-16", sloping slightly away from the pond, so it drains that way. I'm not sure yet how I'll finish it, I've been working my way down from the top of my ponds/stream, doing rockwork, etc. and haven't gotten to the edges of the lower pond. But, I couldn't stand looking at the rubber edges. I used cheap burlap under the sand, which will last 6 months or so before rotting away. By then, I'll have finished things and won't need it. I have to say, it sure looks a lot better this way though!
We've had a colder and wetter spring this year, than the past 4 years. Everyone's is complaining as we normally have some weather like this, 30s at night 40s and 50s in the day, but also get lots of blue skies and 60-75 by this late in the year. It isn't the greatest weather to get enthusiastic about landscaping!