The water appears green, but in fact is very clear. I use orange plastic coated gloves, as being in the water for a while makes your hands very soft, and picking up cobbles can tear the skin on your hands. Sometimes the water gets so mirky that I cant see those orange gloves under the water. We also use a 'Hooka' air breathing mouth piece to go under the water. Operating in the desert is a bit different than when water is available.
Air is used to separate the material.
Today, we use motor powered air blowers, to suspend the material in the riffles, while the box below shakes due to a off center weight connected to a fan blade in the air path in the bottom of the riffle box. Large rocks grind the dirt clods into fine power, thus releasing its grip on small pieces of gold. The large rocks fall off the back of the shaker box, when an excess of rocks pushes them out. I built this summer. The winch is remotely operated by two ropes.