In connection with regulation of the Dokka river system for hydroelectric power production, the aquatic vegetation of the Dokka delta before and immediately after regulation have been investigated, mainly by means of transect analyses including under water photography. As described in this report, the vegetation was found to be rich in species and luxuriant compared to that of the rest of Randsfjorden and dominated by the species Isoetes setacea, Subularia aquatica, Eleocharis acicularis, Ranunculus reptans and Isoetes lacustris. Due to the regulation, the water drains away from the great shallows in late winter and exposes the vegetation to drought and freeze. The drought keeps the Elodea canadensis in check in the delta. However, because of the very extensive delta shallows the delta experiences ice erosion and removal of fine material. The regulation will probably have relatively little short-term impact on the water vegetation. In the long run, however, regulation may contribute to a somewhat faster over-growing of some delta forms because of reduced flood discharge and reduced mud transport in the delta. 59 refs., 22 figs., 18 tabs.