Empress Elisabeth was the aunt of Countess Marie Larisch, the mother of Archduke (and Crown Prince) Rudolph, and the cousin of King Ludwig II of Bavaria.
Lac Leman (also known as Lake Geneva), as was the Starnbergersee, was connected with the death of a royal figure. In this case the death was that of Empress Elisabeth of Austria-Hungary.
From http://www.austrian-mint.com/e/sisihist.html (05 June 2000):
In September, 1898, Elizabeth was staying on Lake Geneva in Switzerland. She was travelling as the Countess of Hohenembs, but it was generally known which high personage was concealed behind that title. An Italian anarchist called Luigi Luccheni had also made his way to Geneva. He wanted to kill the French Duke of Orléans, to strike a blow for "Freedom", for anarchy. But the Duke had already left. Luccheni looked around for someone else important. His choice fell tragically on the Empress Elizabeth. He began to track her.
On the 10th September the Empress and her lady-in-waiting, Countess Sztáray, were hurrying along the quay to catch the steamer across the lake. Suddenly Luccheni sprang at the Empress and stabbed her in the chest with a home-made dagger. At first neither the Empress nor her lady-in-waiting comprehended just what had happened. Only when Elizabeth collapsed on board the ship, and the Countess discovered a patch of blood on her chest did it become apparent that she was the victim of an assassination attempt. The ship put back to shore immediately. But it was too late. The Empress of Austria was already dying.
Members of Bavaria's Wittelsbach royal family show up here and there in The Waste Land, either mentioned outright or as possible allusions. See these Miscellanea pages (ordered as they appear):
For much more information on Marie, her aunt, the Empress, her aunt, the Queen, her archduke cousins, her cousin King Ludwig and other royal and imperial family members visit this webpage elsewhere on this website: http://world.std.com/~raparker/exploring/thewasteland/exmarie.html