River Thames
The Water Music composed by George Frideric Handel premiered on 17 July 1717, when King George I requested a concert on the River Thames. The concert was performed for King George I on his barge and he is said to have enjoyed it so much that he ordered the 50 exhausted musicians to play the suites three times on the trip.
Gottlieb Muffat
It is not known with certainty whether Handel and Muffat had any personal knowledge of each other, but their positions as leading musicians in major European capitals might imply at least a mutual awareness. There is a copy, in Muffat's own hand, of Handels "Suites des pieces" (1720) which Muffat supplied with numerous ornaments along with a few variants of his own design. Modern edition by Hogwood 2007. Muffat as well did his own version of Handels "6 Fugues for Keyboard" (1735) HWV 605-610, first edition from the manuscript by Hogwood 2008. 
For his part, Handel seems to have borrowed extensively from Muffat's "Componimenti Musicali" with at least 18 of these pieces appearing 30 times in Handel's output. Handel's "Ode to St. Cecilia's Day" seems to owe the greatest debt to Muffat, with material from five pieces being reworked into the score. Not only were themes reused in their entirety, but also counter subjects and continuing phrases were put to use by Handel. More such examples appear in Handel's oratorios "Joshua", "Samson", and "Judas Maccabeus". The spirited fugue in the second movement of the Overture to "Samson" makes extensive use of a Muffat fugue from "Componimenti Musicali" and a similar borrowing occurs in the third movement of the Overture to "Judas Maccabeus". The March which begins Act II of "Joshua" is a reworking of a "Rigaudon" by Muffat.