"Plitvice National Park has introduced an online e-ticket system. Tickets can only be purchased in advance, at least 2 days prior to arrival. Entry tickets will still be able to be purchased at the Park, but with the risk that they will not be available because the number of tickets per hour will be limited because of overcrowding, daily Jutarnji list reports. A maximum of 10,000 people per day can visit the park."
Here is the article, which seemed to be 'published' today: