The hole was found on Wednesday, but it appeared to be much worse on Friday. The Sacramento County Office of Emergency Services said residents in the sparsely-populated area should be ready to evacuate if needed.
Most of the day and into the darkness a front loader dumped fist sized rocks into the water side of the levee with little effect. Plastic sheeting was then placed on the land side of the levee hoping to slow the water down.
Lights were brought in at sundown and repair crews will work through the night to make sure there is no levee breach.
Crews investigating the six-foot hole say it was possibly caused by a beaver.
Many residents nearby already had heard about the leak and began evacuating even before the county advisory was put out late Friday afternoon.