Complex sentence: During March 2006 the surface water storage in the dams fell below 25% of full capacity, falling further to 12.8% on 10 March 2008 and reaching an all-time low of 7.7% in December 2009.
Split into simpler sentences: During March 2006 the surface water storage in the dams fell below 25% of full capacity, falling even more to 12.8% as of 10 March 2008. The city's water supply was at an all-time low of 7.7% in December 2009.