Did I mess something up?

General talk
1

I noticed a big blue shape all over the map here:

http://www.openstreetmap.org/?lat=38.738&lon=-77.154&zoom=10&layers=B0FT

If you zoom out it goes away, but zooming closer it is still there. I added a park and pond here:

http://www.openstreetmap.org/?lat=38.80842&lon=-77.11429&zoom=17&layers=B0FT

Could all this blue be from something I did?

2

Yes, it could be that you’re the culprit. Please take a look at the natural=water tag on the map features page and at the pond that you mapped. Is the water on the right-hand-side of the way which defines the pond?

Another possibility is that there is an error in the coastline of the USA somewhere in that area.

3

I think you are seeing the same issue I am seeing in my post…

http://forum.openstreetmap.org/viewtopic.php?id=445

If you look 1/2-3/4 of North America is covered in water when you zoom in close enough.