This picture shows the solution we implemented for our Pergola to block the setting sun. Weights in pockets on both edges enable the curtains to be pulled down to almost double the length you see in the photo.

We aren't dealing with reflection from water though so a full curtain may be the better solution. I would consider attaching the bottom corners of the curtains to the posts and connect them at the centers using velcro to minimize blowing. Don't make them much wider than the span so they can remain taut.

Another option, strategically planted shrubery to screen the reflection near the ground. Perhaps they could be kept low enough to not block the lake view.

Our original thoughts were curtains that could tie back to the posts however we really did not want insect nests and dirt collecting in the folds.

Hopefully others will offer additional ideas.

{{!gwi}}

Your pergola is beautiful. The curtains really set it off nicely. However we need full length material to block that lake glare. It is blinding in the evening until the sun sets. I've considered small shrubbery, but DH doesn't want to lose a bit of view. We are supposed to be able to see through the Sunbrella fabric. I agree about the bugs in the folds. Being close to the lake attracts a lot of them. We get a lot of wind which has blown our patio umbrella and table over; so we have to keep it down most of the time. I'm not sure if the velcro would hold the curtains together or not. I'll give that some thought.

I believe I have seen the screening type of sunbrella fabric. May want to buy a small section and hold it up as a test. If velcro offers insufficient holding strength you could sew buttons, a zipper or install snaps on the binding edge.

Only other thing I think of is a roll-down shade - like the bamboo ones. I'm sure any fabric would work.

Good luck.

fnmroberts,
What did you do for the top of your pergola? Ours is attached to the house; so we had to downsize the top boards a bit to fit under the soffits. Ours has 2x8 boards with 2x2 boards placed 6" on center over them. Still too much sun; so we're thinking about placing vinyl lattice panels on top. We'd use plastic ties to hold the lattice on. That way we can remove them in the winter if we so desire.

Ours has vinyl lattice directly atop the structure. The 4 x 8 panels are nailed only at their corners. Haven't had a problem with snow load but the support structure is 2' x 2'.

{{!gwi}}

If you follow the link at "My Page" you can locate an album showing the construction of ours.

I would use blinds that can be rolled up. Any shear fabric that you can see through will still give you the glare from the sun. We had a mesh umbrella and the sun shone right through it.

You could roll the blind down far enough to stop the glare and still see the lake. If you need something to keep it from flapping around use tablecloth weights attached to some small squeeze type paper clips.

Thanks for the suggestion oilpainter. Fabrics like the Sunbrella I mentioned supposedly cut the sun considerably, but it's still possible to see through them. We had an umbrella like the one you had and it was useless.

To block the glare of the sun off the lake, we need the bottom half of the pergola covered. But we need the top half covered to block the sun itself. I've considered many options. One is to attach a stationary piece of Sunbrella between the support posts. I could stablilize it with a rod at the top and the bottom. I don't think weights would stop the thing from flapping around. There is nothing to block the wind coming across the water. To block out the sunlight, I could make a short rollup Sunbrella curtain for the top half. I think that I'll only have to do this from the outside corner post to the nearest post on each side. One span is 9' and the other is 7'.

This is what we are planning on doing for our covered deck in the Bahamas - using the track.
http://www.mosquitocurtains.com/

I checked the mosquito curtains site you mentioned. Our problem is not with insects. We need to block the afternoon sun and the glare of the setting sun on the lake. Lowes sells Coolaroo sun shades that might work for us.