Thaya (Dyje), River, Lower Austria, meandering western tributary of the March, River, 285 km long. On Austrian territory, long stretches of the river present rather poor water quality (rating 2-3). At Hardegg, the medium flow rate is 10.8 m3/sec. The Deutsche (Austrian, literally "German") Thaya has its source near the town of Schweiggers (alt. 633 m) and flows through the northern part of the Waldviertel Region, along the towns of Vitis (alt. 530 m), Waidhofen an der Thaya (510 m), Dobersberg (465 m), Karlstein an der Thaya (442 m) and Raabs an der Thaya (450 m). At Raabs, the Deutsche Thaya meets a second River Thaya coming in from the Czech Republic, called Maehrische ("Moravian") Thaya/Moravske Dyje. The upper ("Waldviertler") Thaya Valley is a deep, narrow valley lined by numerous castles, palaces and castle ruins. The River Thaya leaves Austrian territory near the town of Drosendorf-Stadt (alt. 423 m) and, except for some minor stretches at Hardegg (alt. 309 m) and Laa an der Thaya (alt. 183 m), flows through the Czech Republic. Upstream of Laa an der Thaya, the Pulkau, River joins the River Thaya from a western direction. Near the towns of Vranov and Nove Mlynyacute (Czech Republic), the River Thaya is heavily dammed up and forms a large reservoir; north of Bernhardsthal (alt. 166 m), it again emerges on Austrian territory, forms the border between Austria and Slovakia and finally meets the River March at Hohenau an der March (alt. 155 m). Plans are underway for a joint national park between Austria and the Czech Republic. The area around the confluence of the River Thaya and the River March on the eastern Austrian national border forms part of the Ramsar National Park, together with the marshlands along the River March.
Literature#Distelverein (ed.), Ramsar-Konzept fuer die March-Thaya-Auen, 1994.