The areas canals don't operate year round. Generally starts in March, ends at different times. Most likely dependent on supply on hand.
Canals are very popular for swimming
The walls to the canal are quite steep, the water travels quite fast, ropes can be rented and can be used to avoid traveling down stream or to climb out of the canal.
Inner tube rentals are available
March 6, 2017 are operational
April 4, 2013 the sluice gate was already shut down