Question: What river separates the bourough where Edgar Wood designed his home?
Context: The River Foyle (from Irish: "an Feabhal" ) is a river in west Ulster in the northwest of the island of Ireland, which flows from the confluence of the rivers Finn and Mourne at the towns of Lifford in County Donegal, Republic of Ireland, and Strabane in County Tyrone, Northern Ireland.  From here it flows to the city of Derry, where it discharges into Lough Foyle and, ultimately, the Atlantic Ocean.  The length of the River Foyle (total) is 129 km (80ml).  The river separates part of County Donegal from parts of both County Londonderry and County Tyrone.  The district of County Donegal that borders the western bank of the River Foyle is traditionally known as the Laggan.  This district includes the villages of St. Johnston and Carrigans, both of which are nestled on the banks of the river. Mansiri Himal is a small, high subrange of the Himalaya in north-central Nepal, about 100 km northwest of Kathmandu.  The Marsyangdi River separates the Mansiri from the Annapurnas to the southwest, then an upper tributary "Dudh Khola" separates "Peri Himal" to the northwest.  On the east side, the "Burhi (Budhi) Gandaki" separates the Mansiri from "Ganesh Himal", "Serang" or "Sringi Himal" and "Kutang Himal".  All these streams are tributary to the Gandaki. Halecroft is a Grade II* listed building in Hale, Greater Manchester (grid reference [ SJ78728636] ).  The building was designed by architect Edgar Wood and was built in 1890; it is an example of Wood's work influenced by the Arts and Crafts Movement.  It is one of 11 Grade II* listed buildings in Trafford.  Halecroft is two storeys high with a one storey 20th century extension. Royd House is a Grade I listed building in Hale, Greater Manchester.  It was designed by architect Edgar Wood as his own home and was built between 1914 and 1916.  The building is regarded as one of the most advanced examples of early twentieth century domestic architecture.  It is one of six Grade I listed buildings in Trafford. West Hudson is the collective name of the municipalities of Kearny, Harrison and East Newark located west of the Hackensack River and east of the Passaic River in Hudson County in northeastern New Jersey.  The Passaic River separates it from Newark and Belleville, and the Hackensack River separates it from Jersey City, the county seat.  Residential districts are concentrated along the banks of the Passaic, while along the Hackensack there is more industry, brownfields, or protected areas of the New Jersey Meadowlands known as the Kearny Meadows or the Kearny Marsh Williamson is a city in Mingo County, West Virginia, United States, along the Tug Fork River.  The population was 3,191 at the 2010 census.  It is the county seat of Mingo County, and is the county's largest and most populous city.  Williamson is home to Southern West Virginia Community and Technical College.  The Tug Fork River separates Williamson from South Williamson, Kentucky. Blaketown is a suburb to the west of Greymouth on the West Coast of New Zealand.  The Grey River separates Blaketown from Cobden, and the Blaketown Lagoon separates it from the centre of Greymouth. The Robert and Esther Armstrong House, also known as Pleasant Hill, is a historic building located in Cedar Rapids, Iowa, United States.  This is the last of two documented houses that regionalist artist Grant Wood designed in its entirety in the city.  There are 14 documented houses that he designed, at least in part, between 1925 and 1933.  He took on the work to help support himself and his mother.  Like his artwork, his house designs evolved from more classical styles to the more simpler lines of vernacular forms.  In addition, he used local materials to construct the house, including the exterior limestone quarried at Stone City for this house.  In addition, Esther Armstrong, local builder Bruce McKay and Wood scoured the countryside looking for design ideas.  They settled on two Pennsylvania-style fieldstone structures, from which Wood designed this home.  He also served as interior decorator as well.  The house was listed on the National Register of Historic Places in 1989. Waddy Butler Wood (1869 - January 25, 1944) was a prominent American architect of the early 20th century and resident of Washington, D.C. Although Wood designed and remodeled numerous private residences, his reputation rested primarily on his larger commissions, such as banks, commercial offices, and government buildings.  His most famous works include the Woodrow Wilson House and the Main Interior Building. Trafford is a metropolitan borough of Greater Manchester, England.  With an estimated population of about 233,300 in 2015, it covers 41 sqmi and includes the towns of Altrincham, Partington, Sale, Stretford and Urmston.  The borough was formed on 1 April 1974 by the Local Government Act 1972 as a merger of the municipal boroughs of Altrincham, Sale, and Stretford, the urban districts of Bowdon, Hale and Urmston and part of Bucklow Rural District.  All were previously in Cheshire, apart from Stretford and Urmston which were in Lancashire.  The River Mersey flows through the borough, separating North Trafford from South Trafford.  Historically the Mersey also acted as the boundary between the historic counties of Lancashire and Cheshire.
Answer: The River Mersey