Thanks! The GitHub project is still available but is many years out of date now. I did this when vector tiles were new, there's now really good software packages out there. Some of the ideas of cleaning and simplifying the data may still be useful though.
@GP: It's never too late to post old stuff in HN if it's interesting. Just add (2013) to the title here. It can also be a post mortem, with the extendd story in your comment, a few maps and the explanations of the main suggested improvements.
https://github.com/NelsonMinar/vector-river-map