The stakes themselves are inside the hazard and are obstructions.
Golf rules water hazard yellow stakes.
Today under the new condensed rules yellow penalty areas are covered under rule 17.
Similar to a yellow staked hazard you must identify the point where your ball crossed into the water but instead of dropping as far back as you want in between that spot and the pin you must drop within two club lengths no closer to the hole.
In either case if you find your ball you always have the option to play the ball as it lies from within the hazard at no penalty.
If your ball is inside this line or even resting on it your ball is in the hazard.
Yellow penalty areas are now covered in rule 17 prior to 2019 water hazards designated by yellow stakes or lines were covered under rule 26 in the rules of golf.
Bear in mind that from within the hazard you are not permitted to rest your club on the ground when addressing the ball.
Informative video about golf course rules at sorrento golf club.