Interesting topic. I'm coming in late and don't know if anyone who replied in 2009 is still around.
For future visitors, however, I'll share some thoughts from the research this topic stimulated. I'm trying to determine if it's possible to have circulating water in my yard through a pump system to simulate a small creek and waterfall, without creating a health hazard or nightmare cleaning situation.
I think in evaluating the safety of copper one should consider the following article which discusses how copper affects adults vs. children. Birds are very sensitive to a lot of things that even children, whose immune systems are still developing, are able to handle. Some natural oils used for deterring pests, for example, can destroy a bird's liver. Even inhaling the fragrance of such oils can metabolize in a bird and result in liver damage.
Considering that birds fly away after frequenting a bird friendly yard, one cannot necessarily determine if their property is really bird friendly or toxic to birds. If one uses the wrong treatment in water, birds may sicken or die after leaving the property. As a result, one must carefully research bird bath safety.
On the issue of copper, therefore, I found this link very enlightening:http://www.health.state.mn.us/divs/eh/water/factsheet/com/copper.html
After reading the article, I'm even reconsidering fitting my house with copper pipes. I didn't realize the complexity of copper and how it works biologically until finding this article (after reading this thread!).
The first link should be taken with a grain of salt, because there are safe options to algae remover. I have two lovebirds that are five years old, and have added a little apple cider vinegar, a tiny amount of iodine, and a few drops of natural water clarifier without any adverse health impact.
Having said that, this article is short, sweet, and I believe sets a baseline for cautiously approaching additions to a bird bath or fountain that is bird friendly:http://www.birdwatchersgeneralstore.com/algae.htm
This article got me to thinking that getting a setup -- whether it's simulated creeks, waterfalls, or just a nice Roman fountain -- should involve simplicity of design. Lots of rocks, nooks and crannies are going to impede fast and efficient cleaning. One should also consider the frequency of water evacuation (without undue water waste in these global warming times). That way, one can take a hose with a power attachment and "attack" the infrastructure quickly and efficiently, so you don't get discouraged in upkeep over time.
You know what scares me about researching algae remover (aka algaecide)? There is obviously such a huge industry that I cannot find any objective articles, not even from the National Institute of Health (NIH), that really give the lowdown on chemical safety. That is why I'm leaning toward that link about from Bird Watcher's General Store as a good starting point for planning a bird water source in one's yard.
However, there are natural alternatives that remove huge "algae blooms" from large lakes, that lead me to believe it is critical to research algaecide alternatives. Here is a use case of what I'm talking about:http://www.ilsrc.com/algae-removal
Bird physiology is different from fish and other aquatic life, so I wouldn't assume what is safe for fish is safe for birds. A bird's body is extremely complex and its liver sensitive. Again, just because birds are frolicking in the bath doesn't necessarily mean it's "bird friendly," because one will never know if a particular bird stopped showing up because it moved on, or if it got sick and died.
As a bird lover, therefore, I'm willing to go the extra mile so that I have a clean conscience knowing that my yard is not toxic to birds, which are essential for this planet's ecosystem. These are my thoughts after reading this thread that I wanted to share. If anyone disagrees, by all means contradict me.