What is an outlet current?
An outlet current is a powerful channel of water flowing from river mouths or similar water outlets into the lake. These currents can be strong enough to sweep you into the lake (where water is deeper). Though the current coming from a river mouth (or other outlet) is not always strong, it can be enhanced by strong longshore currents during times of moderate to high waves. The longshore current acts as a "feeder" current, moving water into the pre-existing channel carved out by the river. The outlet current may also be enhanced after a heavy or prolonged period of rain, when the river flow is stronger.
Image 1. Au Train river mouth at Au Train, Michigan. This area has seen several current-related rescues. Some of them have been associated with the outlet current at the river mouth. Others were associated with classic rip currents (the channels carved out by the rip currents can be seen to the left of the river mouth). The contrast of this image was altered to highlight the channel carved out at the river mouth from the outlet current and the old rip current channels to the left of the river mouth. Image is from Google Maps (2012).
Image 2. An zoomed-in view of the channel carved into the sand by the outlet current. Au Train, Michigan. The contrast of this image was altered to highlight the channel carved out at the river mouth from the outlet current. Image is from Google Maps, 2012.
Escaping Outlet Currents
Outlet currents are actually a type of rip current, so the escape methods for outlet currents are the same as a rip current. A best practice, however, is to AVOID outlet currents by choosing not to swim near a river mouth or similar outlet.