The congestion problem usually occurs due to multiple traffic flows in a mono-sink wireless sensor network (WSN) which leads to excessive energy consumption and severe information loss. To solve this problem, a novel Congestion Alleviation Procedure (CAP) has been proposed. It exploits the characteristics of the sensor nodes and the wireless links between them. CAP mitigates congestion reactively by either bypassing the affected node and wireless link or rerouting the traffic to a less congested and energy efficient route. The performance evaluation based on the simulation performed in the network simulator (ns-2.35) shows that CAP improves Packet Delivery Ratio (PDR) by 45, throughput by 39, ETE delay by 32, and energy consumption per data packet by 47 as compared to No Congestion Control (NOCC) mechanism. © 2016 IEEE.