Complex sentence: Although winterbourne until Great Shefford the river had not been dry below Lynch Wood in 2007 and 2008, but dried up in June-July 2009 and the riverbed remained dry until January 2010 due to 4-5 inches of snow melting in a thaw.
Split into simpler sentences: Although winterbourne until Great Shefford the river was not dry below Lynch Wood in 2007-2008. However, it dried up in June-July 2009 and the riverbed remained dry until January 2010 due to 4-5 inches of snow melting in a thaw.