route of these rivers accompanies a high altimetric gradient that favors the construction of hydroelectric power plants, so much that some barrages are in functioning as in the Pitangui River. The drainage pattern normally found is radial. Pitangui River, one of the most important rivers of the municipality was dammed in 1939 originating the Dam of the Alagados. The same is responsible for the water supply in the city, also by the direct capture of the river. There are, however, problems associated with aggradation and eutrophication. The presence of agriculture, industrial effluents and vehicular traffic instead of the riparian forest affects the chemistry of water with levels of chlorides, phosphors and alkaline. In all there are 12 drainage basins in the municipality. They are: Ronda, Olarias, Pilão de Pedra, Lajeado Grande, Santa Tereza, Cará-Cará, Francelina, Santa Monica, Grande Arroyo, Taquari, Colônia Adelaide and Gertudes. Of these, there are four streams that are born in the urban perimeter, they were buried and channeled for greater integration of the city. In the past they will have historical importance, but today some watercourses are treated as "sewage" by the local population. Others like arroyo de Madureira had bathing status. With rapid urbanization and without efficient public policies, several arroyos, especially in the 1980s, were occupied by irregular housing. By that it aggravated the quality of the municipal air, a singular characteristic before other cities of Paraná. Limits It borders seven municipalities as a whole, although their downtown may be more than 56 miles (90 km) in some cases. To the north are the towns of Castro and Carambeí and Tibagi, to the south are the towns of Palmeira and Teixeira Soares, to the east is the city of Campo Largo, and to the west is Ipiranga. Demographics For the data collected by the census the population in 2010 was 311,611 inhabitants with a density of 150.72 inhabitants/km2, for an estimate of 2018 the value is 348,043 inhabitants of Paraná. For IPARDES the estimate for 2030 is 381,051 inhabitants, a burden of 109.48%, but for this simulation, São José dos Pinhais would surpass Ponta Grossa in population, which would lower the second to the fifth place in the state. Historically its geographical condition was important for the population increase, from the breeding and wintering to the yerba mate and wood and finally the services sector. Ponta Grossa grew faster in the late 17th century,