River Chess: The river Chess is a chalk stream that rises in the hills beyond Chesham and flows down to join the river Colne at Rickmansworth. Typical chalk streams like the Chess are shallow, narrow, with gravel beds and clear, warm water. They are fed by groundwater, which is stored in the aquifer – layers of chalk rock which work like a sponge, soaking up water until it emerges at ground level. The Chess once powered watermills and supported the watercress industry.
The River Chess fall is 200 feet (60 m), and its length is 11 miles (18 km).