Question: The birthplacce of Ian Johnston is located on what river?

Context paragraphs:
White Oak Plantation: White Oak Plantation, also known as the William Johnson House, is a historic plantation house located near Charlotte, Mecklenburg County, North Carolina.  It was built about 1792, and is a two-story, Catawba River Valley School style brick dwelling.  The original Quaker plan interior has been converted to a center hall plan.  It has a gable roof overhang and a full-width, two-story gabled porch.  It was built by William Johnston, a captain in the North Carolina militia at the Battle of King's Mountain in 1780.

David Johnston (rugby union, born 1958): David Ian Johnston (born 20 October 1958) is a Scottish former rugby union player.  Johnston played 27 times at centre for the Scotland national rugby union team.  He was formerly a commercial property partner in Burness Solicitors.

Belfast: Belfast ( or ; from Irish: "Béal Feirste" , meaning "rivermouth of the sandbanks" ) is the capital and largest city of Northern Ireland, and the second largest on the island of Ireland.  On the River Lagan, it had a population of 333,871 in 2015.  Belfast was granted city status in 1888.

Robbie Johnston: Robert ("Robbie") Ian Johnston (born 21 August 1967 in Balclutha) is a former long-distance runner from New Zealand who competed twice at the Summer Olympic Games and once at the Commonwealth Games.  At the 1992 Summer Olympics in Barcelona he was ninth in his heat of the 5000m and did not advance to the final.  At the 1996 Summer Olympics in Atlanta he was 12th in his heat of the 10000m and did not advance to the final.  At the 1994 Commonwealth Games in Vancouver he did not finish the 10000m.

Smithfield, North Carolina: Smithfield is a town in Johnston County, North Carolina, United States.  In 2016, the estimated population was 12,266.  It is the county seat of Johnston County.  Smithfield is home to the Ava Gardner Museum and is situated along the Neuse River, where visitors enjoy the annual Smithfield Ham and Yam Festival, walks along the Buffalo Creek Greenway and the historic downtown district.  The town is located in North Carolina's famed Research Triangle and is approximately 29 mi southeast of downtown Raleigh.  The Raleigh-Durham-Cary Combined Statistical area has a population of over 2 million residents.

WKSX-FM: WKSX-FM is an oldies music formatted radio station located in Johnston, South Carolina, and is part of the Augusta, Georgia, radio market (mostly on the South Carolina side of the Savannah River).  The station is licensed by the Federal Communications Commission (FCC) to broadcast at 92.7 FM with an effective radiated power (ERP) of 1.8 kW.

WXK22: WXK22 (sometimes referred to as Sherman All Hazards) is a NOAA Weather Radio station that serves Sherman-Denison and surrounding areas near the Red River.  It is programmed from the NWS Fort Worth office with its transmitter located in Sherman.  It broadcasts weather and hazard information for Collin, Cooke, Denton, Fannin, and Grayson counties in Texas as well as Bryan, Carter, Johnston, Love, and Marshall counties in Oklahoma.  It also broadcasts hourly weather observations for the following locations: Sherman-Denison, Durant (Oklahoma), Gainesville, McKinney, DFW Airport, Paris, Wichita Falls, and Oklahoma City (Oklahoma).

Neuse River Trail: The Neuse River Trail is a 33 mi long paved greenway located in the Research Triangle region of North Carolina, running along the banks of the Neuse River from Falls Lake Dam to the town of Clayton.  The route passes through the jurisdictions of Raleigh, Wake Forest, Knightdale, and Clayton in Wake and Johnston counties.  The Neuse River Greenway trail is part of the Capital Area Greenway system as well as the Mountains-to-Sea Trail that crosses North Carolina from the Great Smoky Mountains to the Outer Banks.  Open to both cyclists and pedestrians, the Neuse River Trail is the longest greenway trail in North Carolina and the longest paved trail between northern Virginia and western Georgia.

Ian Johnston (cricketer): Robert Ian Johnston usually known as Ian Johnston (born 1 July 1948 in Belfast, Northern Ireland) is an Irish former cricketer.  A right-handed batsman and right-arm medium pace bowler, he played 15 times for the Ireland cricket team between 1979 and 1983, including three first-class matches and two List A matches.

Ian Johnston (doctor): Ian Johnston ("Walter Ian Harewood Johnston, 16 February 1930 – 19 March 2001") was one of the true pioneers of reproductive medicine in Australia.  He was a primary contributor to the development of human IVF (In vitro fertilisation) in Melbourne, Australia.  He was the Head of the Reproductive Biology Unit at the Royal Women's Hospital, Melbourne and was the founding President and Honorary Life Member of The Fertility Society of Australia.  Ian was known as the 'founding father of IVF in Australia'

Supporting paragraphs: Ian Johnston (cricketer) Belfast
Answer: River Lagan