Porcupine Lake is a 280 hectare water-body located in the Township of Whitney, with a combined drainage area of 87 km².
It receives inflow from the Upper Porcupine River as well as Bob’s Creek, which drains Bob’s Lake located northeast of Porcupine Lake.
With a flat topography, the maximum depth of Porcupine Lake is 5 meters. This shallow depth results in no thermal stratification and an ortho grade dissolved oxygen profile.
The bottom of the lake is composed of sandy-clay and clay-silt. The Porcupine River begins at Porcupine Lake at an elevation of 277 m and flows northeast under Ontario Highway 101 out of the lake at the community of Porcupine. It continues to flow northeast where it joins with the left tributary, the North Porcupine River. It then flows southeast through the Township of Hoyle and again under Ontario Highway 101 where it reaches its mouth at the northwest corner of Night Hawk Lake at an elevation of 247 m.
The length of the Porcupine River from its outlet at the northeast end of Porcupine Lake to its mouth at Night Hawk Lake is approximately 35 km in total. The North Porcupine River tributary originates at Bigwater Lake and flows eastward for approximately 25 km to its confluence with the Porcupine River.