Question: How long is the river which University Oval, Adelaide is located on?

Context paragraphs:
River Torrens: The River Torrens is the most significant river of the Adelaide Plains and was one of the reasons for the siting of the city of Adelaide, capital of South Australia.  It flows 85 km from its source in the Adelaide Hills near Mount Pleasant, across the Adelaide Plains, past the city centre and empties into Gulf St Vincent between Henley Beach South and West Beach.  The upper stretches of the river and the reservoirs in its watershed supply a significant part of the city's water supply.  The river's long linear parks and a constructed lake in the lower stretch are iconic of the city.

Absa Puk Oval: The Absa Puk Oval, formerly known as the Fanie du Toit Sports Complex and the University Oval is a cricket ground in Potchefstroom, South Africa.

Adelaide University Cricket Club: The Adelaide University Cricket Club is an amateur cricket club based in Adelaide, South Australia.  It is an affiliate of the Adelaide University Sports Association and plays in the Premier League of the South Australian Cricket Association.  Although the club is associated with the University of Adelaide, players do not have to be students.  Home matches are played at University Oval.

University of Wollongong Titans: The University of Wollongong Titans (or UOW Titans) is an Australian rugby league football team based in Wollongong.  The club are a part of Country Rugby League and competes in the Illawarra Rugby League premiership.  The club plays out of University Oval, Wollongong.  The Titans wear red, navy and white jerseys.  An earlier team from the University of Wollongong were nicknamed the "Books".

Umpire Decision Review System: The Umpire Decision Review System (abbreviated as UDRS or DRS) is a technology-based system used in the sport of cricket.  The system was first introduced in Test cricket, for the sole purpose of reviewing controversial decisions made by the on-field umpires as to whether or not a batsman/batswoman had been dismissed.  The system was first tested in an India v Sri Lanka match in 2008, and was officially launched by the International Cricket Council (ICC) on 24 November 2009 during the first Test match between New Zealand and Pakistan at the University Oval in Dunedin.  It was first used in One Day Internationals (ODI) in January 2011, during England's tour of Australia.  The ICC initially made the UDRS mandatory in all international matches, but later made its use optional, so that the system would only be used if both teams agree.  The ICC has agreed to continue to work on the technology and will try to incorporate its use into all ICC events.

Kensington Oval, Dunedin: The Kensington Oval, formerly known as the South Dunedin Recreation Ground, is a park and sports ground in Kensington, Dunedin, New Zealand.  It is also known as just The Oval, although this name has become less common in recent years due to the potential confusion with the University Oval in the north of the city.

University Oval, Adelaide: University Oval, referred to by the University of Adelaide, Adelaide University Sports Association and various other groups, is a part of Park 12 in the Adelaide Parklands located across the River Torrens opposite the University of Adelaide.  Park 12 is bounded by North Terrace, Frome Road, Sir Edwin Smith Avenue and King William Road

Adelaide University Football Club: The Adelaide University Football Club Inc. (AUFC) is a South Australian based amateur Australian rules football club that hasn't won a Division 1 flag since 1999.  It is an affiliate of the Adelaide University Sports Assoc. and plays in the SAAFL.  The club promotes itself as the largest amateur football club in Australia.  The club trains on Beautiful University Oval located across the river from the University which forms part of Park 12, and Park 10 in the portion of the Adelaide Parklands between the University and North Adelaide.  It is one of the most decorated clubs in the University's history.  The Club has played in every season of the SAAFL competition, won 23 Division 1 premierships, had 8 Division 1 medallists, 48 state players, 4 All-Australian captains (McLeod, Muir, Rofe, J.F. Sangster), and the first AAFC Carnival medallist to play for S.A. (Paul Rofe).

University Azzurri FC: University Azzurri Football Club is an Australian semi-professional football club based in Darwin, the Northern Territory.  Founded in 1999 as University Rangers, the club merged with Nakara Azzurri in 2010 to form University Azzurri.  The club currently competes in the NorZone Premier League, with matches played at University Oval.  The club maintains affiliation with Charles Darwin University.

University Oval, Sydney: University Oval is a cricket ground at the University of Sydney, in Sydney, Australia.  The first recorded match on the ground was in 1898, when it was the venue for a game between the Australian Universities and A. E. Stoddart's XI.  The ground has also hosted a Women's Test match between Australia and New Zealand.

Supporting paragraphs: University Oval, Adelaide River Torrens
Answer: 85 km