The average 30-year treasury bond rate is 3.09 percent, according to the U.S. Treasury Department's website, as of June 29, 2015. However the bond rate fluctuates and can vary on a daily basis. The daily 30-year treasury bond rate can be found at the U.S. Treasury Department's website.
The U.S. Treasury Department is the government agency responsible for setting the 30-year treasury bond's rate. In 2002, the U.S. government briefly stopped issuing 30-year treasury bonds and replaced them with the 10-year treasury bond. Due to investor demand, the government brought back the 30-year treasury bond in February 2006. Currently the government offers the 30-year treasury bond on a quarterly basis.