Another problem of the upper Rhine is that of its water power, a matter which had proved difficult to adjust between Baden and the Reichsland and was likely to make greater trouble between two sovereign and antagonistic states. Alsace had complained that the Grand Duchy opposed plans for the utilization of the Rhine, and France proposed to take no chances of future disagreement. So Germany agrees that, subject to the approval of the Central Commission, France may build dams and take water from the Rhine on the whole course of the river between the extreme points of the French frontier, acquiring for proper compensation the necessary supports and rights of way on the Right Bank, with the understanding that Germany has a right to the value of half the power thus produced. Germany binds herself not to derive canals from the Rhine opposite the French frontiers.[34] Henceforth the Rhine is to be harnessed to serve the needs of Alsace. * * * * * If participation in the affairs of the upper Rhine was incidental to the recovery of Alsace, the lower course of the river was quite another matter. Between the Rhine and the Franco-Belgian frontier lay a belt of German territory, varying in breadth from fifty to one hundred miles, with an area of about 10,000 square miles, and a population of five and a half millions. Of these, nearly a million were in the Bavarian Palatinate, 50,000 in the principality of Birkenfeld, about 400,000 in Hesse; the rest, the great majority, were in the Rheinprovinz of Prussia. Practically all of them spoke German. They had been under their existing governments for at least a century; they had been under some sort of German government far longer. Down to 1789 this region was parcelled out among a great number of petty principalities, lay or ecclesiastical, from the considerable dominions of the archbishoprics of Mainz, Trier, and Cologne, and the bishoprics of Speier and Worms, to the minute lay states of a few villages which can scarcely be distinguished on the map. A careful historian has counted ninety-seven such independent states on the Left Bank in 1789. Swept away by the Revolution, most of them were never restored. The chief exception was the Palatinate, which had passed about from one branch of the reigning family to another, and came back to Bavaria in 1815 as a well rounded territory under the house of Zweibrücken. The Congress of Vienna also handed over the valley of the Nahe to Hesse-Darmstadt, and gave the duke of Oldenburg a compensation of 25,000 souls to be furnished by Prussia, 20,000 of which were found on the Left Bank and formed into the principality of Birkenfeld.