The O'Donnel River is about 40 kilometres long and flows south from its headwaters and then west into Atlin Lake. The gold placers occur midway along its length at the abandoned town of O'Donnel which is about 34 kilometres southeast of the community of Atlin and road accessible from Atlin.

The river flows over limestones of the upper Mississippian to Permian Horsefeed Formation (Cache Creek Complex) and cherts and argillites of the Mississippian to Triassic Kedahda Formation (Cache Creek Complex). Immediately east of the creek is a large body of quartz diorite of the Early Tertiary McMaster stock (Geological Survey of Canada Open File 1565). There are no lode gold showings in the area.

The occurrence was discovered in 1898 during the initial discovery years in Atlin but received little or no work thereafter until 1913 when the Canadian Alaska Exploration Co. discovered a pay streak 3 to 5 metres above the creek bed. It was worked by both underground and hydraulic methods intensively for about seven years. Sporadic small-scale operations were done until 1939, and recently seismic surveys were done in 1973 and 1974. Approximately 200,770 grams of gold were recovered from the creek between 1898 and 1945 (Bulletin 28). Aitken (1959) said that "this creek was never worked for a profit" (Geological Survey of Canada Memoir 307).

In 2019, a program of GPS elevation surveying, prospecting, hand trenching and small-scale test sluicing was completed on O'Donnel River in an effort to locate and assess channel gravels. Prospecting included hand panning and assessing the various gravel banks and other similar exposures on the northern and southern parts of the property. Preliminary work on the southern part of the property encountered two possible ground sluice cuts, one drift, one shaft and several old hand pits and trenches. Exposed gravels were panned but no gold was recovered. A large amount of clay exists along much of the exposed face of the west bench and it is felt that the best placer potential lies about 40-80 metres west of the current bank exposures. Given the limited likelihood of hand testing being able to access basal gravels along the west bank in the southern part of the property, exploration efforts shifted to the northern part of the property. Preliminary work on the northern part of the property encountered two ground sluicing cuts and the remnants of an old water flume system but no drifting or shafting was noted, suggesting that the majority of the bench deposit remains untouched and intact in this area. Although interesting amounts of gold averaging approximately 1 ounce every 19.5 cubic metres were encountered from a 1.5 metre thick pay layer, the resultant pay to stripping ratio of as little as 1 to 18.3 to as much as 1 to 22.3 makes these grades currently uneconomic. Further work is warranted to test whether the test results represent a low grade portion of the deposit and grades improve along strike (Assessment Report 38819).