In its natural state, Hamilton and environs was very swampy in winter with 30 small lakes connected to surrounding peatlands. Hamilton was surrounded by 7 large peat bogs such as Komakorau to the North and Rukuhia and Moanatuatua to the South, as well as many smaller ones all of which have now been drained with only small remnants remaining. The total area of peat bog was about 655 km2. Early photos of Hamilton East show carts buried up to their axles in thick mud. Up until the 1880s it was possible to row and drag a dinghy from the city to many outlying farms to the North East. This swampy, damp environment was at the time thought to be an ideal breeding ground for the TB bacillus, which was a major health hazard in the pioneering days. The first Hamilton hospital was constructed on a hill to avoid this problem. One of the reasons why population growth was so slow in Hamilton until the 1920s was the great difficulty in bridging the many arms of the deep swampy gullies that cross the city. Hamilton has 6 major dendritic gully complexes with the 15 km long, 12 branch, Kirikiriroa system being in the north of the city and the southern Mystery creek-Kaipaki gully complex being the largest. Others are Mangakotukutuku, Mangaonua and Waitawhiriwhiri.