Using a sample of 407 RR Lyrae stars extracted from SDSS Stripe 82 , we study the degree of substructure in the Galactic halo .
We identify overdensities associated with the known substructures of the Hercules-Aquila Cloud and the Sagittarius Stream , and find a further previously-unknown substructure , the Pisces Overdensity , at \sim 100 kpc from the Sun .
Together , the three substructures account for \sim 80 \% of our RR Lyrae sample .
We also study the density distribution of RR Lyraes in the halo and find that the profile is best fit by a broken power law with an inner slope of -2.4 and a break radius of \sim 25 kpc , consistent with previous studies .
We conclude that the halo is predominantly made up of the debris from in-falling satellites , with little or no underlying smooth component .