The paper includes a description of 25-five interlocked boulder block ramps with increased roughness located on Porębianka creek and presents an analysis how those low head hydraulic structures fit to a natural river system: riffle-pool. These block ramps with increased roughness structures might be called "close to the nature", and in hydraulics engineering they are replacing traditional drop hydraulic structures. One of the main advantages of block ramps is that they are supposed to be placed in a natural sequence distances which follows pools and riffles pattern along a river, also block ramps allows free movement of fish upstream and downstream without necessity of fish pass constructio
