The Madek River is one of the remaining unpolluted rivers in the Johor state. It length of about 40 km originates from one of the highest mountains in Peninsula Malaysia, the Belumut Mountain, from a height of 1010 metres above sea level, and commands a catchments area of 150 sq km, flowing through all the permanent forest reserved areas.

The water from Belumut mountain reserve flows southward to the Linggui River where a Linggui dam is built for water supply to Singapore. Thus consumers would understand that the water to cultivate Kahang rice they consume is the water from the same source. The Bulumut mountain reserve has its water flowing northwards forming the Madek river where the water is used for planting the Kahang Organic Rice Farm.

In the catchment area there are tropical rainforest animals like elephants, wild boars, monkeys, mouse deers, squirrels, iguana, barn owls, flying foxes etc. In the river are homes of the renowned silver arowana (a protected fish specie), ikan tapah weighing up to 30kg found during the Nov ~ Jan northeast monsoon. The green catfish (buang), marble goby (soonhock), giant snakeheads (toman) up to 10kg, snakeheads (haruan), featherbacks (belida), Malaysia bony-tongue (arowana - kelesa) etc are some of the few found in the river. The year round water availability from the Madek river is sufficient to irrigate the Kahang Organic Rice Eco Farm (KOREF) padi fields even at extreme dry seasons.

Trekking starts at Sungei Temigol (behind KOREF) for about 1km before arriving at the junction of Sungei Temigol and Sungei Madek. The trek will continue downstream of Madek for about another 1.8 km before arriving at the sandy beach about 500M away from the junction of Sungei Madek and Sungei Kahang. Most part of the river trekking is less than chest depth but life jackets shall be worn regardless of the swimming competency of the trekkers. Trekking guides will also be companied based on a minimum ratio of 1 : 5 trekkers depending on the type of trekkers. The trek is not physically demanding as it is walking downstream all the way. One can even swim or float along the river downstream. The entire trek will take approximately 2 1/2 hours for novice trekkers.