In the foundation charter of Selkirk Abbey, granted by
King David in the twelfth century, the native name is translated as Garua in Latin, which in later documents mutated into Zarof, Yharrow and Yara, before assuming its present form of Yarrow. The area of the parish of Yarrow was formerly one of the most extensive in the south of Scotland, encompassing most of the valley of the Yarrow and a considerable part of that of the Ettrick. The shape was very irregular and, although the population was low (1,264 in 1841), it was difficult for the minister of the parish to reach many of them, both as regards distance and the want of roads and bridges. To ameliorate this problem, the
Duke of Buccleuch in 1851 instigated proceedings to have the southern part, in the
Ettrick valley, disjoined from the parish and erected into a separate parish. The duke proposed to make over the chapel at
Ettrickbridge, which he had built in 1839, to be the church of the new parish, to erect a suitable manse for the minister, and to bear the expense of the judicial separation proceedings. The new parish would extend to 9 miles in length up the river Ettrick, be about 6 miles wide, with an area of about 50 square miles, population 600. The remaining portion of the parish of Yarrow would contain a population of about 670, extending in length to about 19 miles, and in breadth. The new parish was created and named Kirkhope, an old name for the Ettrickbridge area Thus the population of Yarrow Parish had reduced from 1,270 to 600 by this separation and it would fall further to 500 in 1901 In 1891 the Boundary Commissioners transferred the
Megget district from the Peeblesshire parish of
Lyne and Megget to Yarrow (while Yarrow lost some detached and outlying parts to Peeblesshire parishes). The Megget valley lies to the west of St. Mary's Loch and
Megget Water feeds into that loch. Much of the valley was flooded by
Megget reservoir which was opened in September 1983. ==See also==