Getting to the bridge that crosses Rio Urirque just above the confluence will take some effort.  From the town of Choix in Sinaloa take the right road at junction just north of town (a couple of Kms).  Then follow the dirt road as it winds around and eventually makes it to the confluence.  From Choix you are looking at 100Km or so to the take out.  To find the take out you would be best to get the GPS points and plot the route carefully using google earth.

You can continue paddling down the Rio Fuerte to cut out some of the driving time and take out above the reservoir but the river is more flat here.