Building of bypass
Jasiołka River – km 27+960
Planned term of start:
IVth quarter 2019
Planned term of end:
IIIrd quarter 2020
1 209 354 Polish zloty
Why do we interfere in a river?
The weir made in the 30-ties of the 20th century serves to maintain the water level of municipal water intake for Krosno. It wasn’t equipped with any device for fish migration.
The weir damming water is divided into 3 sections. Two extreme ones are equipped with steel bolts. The middle section has a form of spillway. Below the overflow a cascade consisting of 3 steps and ending with a stilling basin with a concrete diaphragm wall was built. Below the stilling basin a stone rapid built from large boulders was made.
On the right bank above the weir a water intake and a treatment plant are situated. On the left bank there are clearly visible traces of a bypass weir by flood water. It is a natural place in which fish pass is designed.
According to proposed modernization a fish pass shaped as canal bypass of the weir on the left side of the river is designed. The fish pass will be a bypass imitating a natural river stretch shaped as a winding route which will eliminate level difference and minimize water speed.
Pools forming the fish pass will be separated by bolts of large size boulders. Additionally, the fish pass will be equipped with a rest pool situated in the middle of the route. Apertures in 30 cm partitions help fish pass the whole route.
An inlet to the fish pass from the side of upper water will be protected by a stone overlay and a wall of sheet piling. An outlet from the side of down water will be ended by a diaphragm wall of boulders on the whole broad of the riverbed in order to concentrate water in low flows.