The river rises in country east of Mount Dale and flows north-west to Mundaring Weir, where it is dammed.

O'Connor (formerly the Helena River Reservoir) a range of named creeks that occur in State Forest no 71 and 13: In higher ground the Helena River passes mainly through State Forest or reserve.

At Darlington, and the locality of Helena Valley there is housing and agriculture on its banks before it emerges out on to the Swan Coastal Plain.

Due to this, restrictions in the Helena River catchment have been made to not allow activities that affect the quality of the Pipehead Dam – despite being adjacent to the built up areas within the Shire of Mundaring on the north side of the Helena River catchment.

[1][2] The bridges design and strength were relevant to higher water flow prior to the construction of the Pipehead Dam, as significant flooding occurred in the early and mid twentieth century.