In extreme weather conditions with heavy rain in a short time, the discharge may be much higher; the highest peak was 19.5 cubic metres per second (690 cu ft/s) on 25 May 1978.

Soon after its nominal source, it is joined by the much larger Erlenbach, which rises at the Hussars Fountain, 5 kilometres (3 mi) further south, on the Eschkopf, at an elevation of 460 metres (1,510 ft).

Below Frankeneck, where the broader Lambrecht valley begins, the Speyerbach takes from the left's most important water supplier, the nearly 20-kilometre (12 mi) long Hochspeyerbach, and changes its direction to the southeast.

The Speyerbach breaks the eastern ridge of the Palatinate Forest shortly before Neustadt an der Weinstrasse.

Transportation was done by drifting of logs or timber up to about 1.40 metres (4.6 ft) long; the water discharge was too low for rafts made of tree trunks.

The timber was collected before being left in artificial ponds called Woogen or 'Klausen', to be drifted in spring, as the snow melt began.

The middle and lower reaches of today's Speyerbach, are largely the product of human intervention, both in terms of its course and its being canalized.

The meanders that existed during the Spanish Succession War led to the undoing of both French and Imperial troops during the Battle of Speyerbach in September 1703.

The project was completed in June 2010, at a cost of 2.7 million euro, most of which was paid by the state of Rhineland-Palatinate[1] The lower reaches of the Speyerbach, east of Neustadt, flowing South-East to Speyer were probably created by the Romans to transport timberfrom the Palatinate Forest to Noviomagus Nemetum, the Germanic precursor of Speyer.

Previously, it probably followed a more northerly course, south of Haßloch and then along the course of the current Ranschgraben, taking up the Rehbach near Limburgerhof-Rehhütte and flowing into the Rhine between Altrincham and Ludwigshafen.

The distributaries Rehbach (splitting off at Neustadt) and Woogbach (at Hanhofen) are both artificial; they were created in the Late Middle Ages.

The Forestry Museum Elmstein, situated in the house of Heinrich Haag, the last blacksmith, provides the public since 1990 with information about working in the forest, including drifting on the Speyerbach.

Because the raw material (wood) and a supply of energy (water) were available next to each other, large paper mills developed in Lambrecht valley in the 19th century.