he River Lynch, also known as the Lynch Brook, is a minor tributary of the River Lea, in Hoddesdon, in which UK country? 
England
Title: Rags Brook
Passage: Rags Brook is a tributary of the Small River Lea, which is a tributary of the River Lea.  Rags Brook rises in the hills between Goffs Oak Cuffley in Hertfordshire, England.  Brookfield Lane follows the course of the brook and the Brookfield Centre reflects the brook in its name.
Title: River Lynch
Passage: The River Lynch, also known as the Lynch Brook, is a minor tributary of the River Lea in Hoddesdon, Hertfordshire, England.
Title: River Lea
Passage: The River Lea in England originates in Marsh Farm, Leagrave, Luton in the Chiltern Hills and flows generally southeast, east, and then south through east London where it meets the River Thames, the last section being known as Bow Creek.  It is one of the largest rivers in London and the easternmost major tributary of the Thames.  Its valley creates a long chain of marshy ground along its lower length, much of which has been used for gravel and mineral extraction, reservoirs and industry.  Much of the river has been canalised to provide a navigable route for boats into eastern Hertfordshire, known as the Lee Navigation.  While the lower Lea remains somewhat polluted, its upper stretch and tributaries, classified as chalk streams, are a major source of drinking water for London.  A diversion known as the New River, opened in 1613, abstracts clean water away from the lower stretch of the river for drinking.  Its origins in the Chilterns contribute to the extreme hardness (high mineral content) of London tap water.
River Lea River Lynch