Wrap the 1/2-inch diameter chain through a hole on the cinder block and around the pump where the PVC tube connects to the pump's outflow hose. Use the chain cutter to cut the chain and then crimp it closed with the wrench. Leave 8 to 10 inches of a loop in the chain between the cinder block and the pump.
Run the pump to the river with the cinder block and set on the river bank. Go into the river and gauge the depth of the water. If the water is too cold. use a long dipstick to check the river depth. Keep the pump as close to the surface as possible for ease of repair or retrieval.
Inspect the river bottom for large rocks or tree stumps. Place the cinder block on the current side of any large rock. Keep the pump on the upward side of the current against the obstacle.
Lower the pump and cinder block into the river and let the pump extend out to the river bottom at an angle of 45 degrees. Let the pump fill with water to prime. Let the cinder block drop to the river bottom while the pump fills with water.
Check the pump every two days to see if the area is attracting aquatic plants or detritus. Move the pump to a location where the plants or river flotsam do not flow into the pump.