The Gudbrandsdalslågen, draining higher elevations and being primarily glacier fed, typically crests later than the Glomma river, which drains the east valleys. In the rare year when both crest at the same time, their confluence at Nes is the site of great floods. The most famous simultaneous crest of the Gudbrandsdalslågen and Glomma rivers resulted in the flood that took place on 20–23 July 1789, with crests over 50 feet (15 m) above the average level of the water.