Question: Turnford Brook flows through a borough that covers how many square miles ?

Context paragraphs:
Farleys Brook: Farleys Brook is the name of a minor watercourse in Hucknall, Nottinghamshire.  It rises in a pool within a copse close to the M1 motorway at the foot of the Misk Hills.  It flows Southeastwards through the Misk Meadows, Pennine View, and Nabbs Lane Estates, where several parks and open spaces are centred on flood prevention lagoons.  The Brook flows past Hucknall Aerodrome and into Bulwell Hall Park, following the A611 Hucknall Bypass.  Farleys Lane Spring rises in the Brook close to this point and a deep pool is formed which is used for paddling and bathing.  The Brook flows into the River Leen at Moorbridge, Bulwell.

Trona Pinnacles: The Trona Pinnacles are an unusual geological feature in the California Desert National Conservation Area.  The unusual landscape consists of more than 500 tufa spires (porous rock formed as a deposit when springs interact with other bodies of water), some as high as 140 ft , rising from the bed of the Searles Lake (dry) basin.  The pinnacles vary in size and shape from short and squat to tall and thin, and are composed primarily of calcium carbonate (tufa).  They now sit isolated and slowly crumbling away near the south end of the valley, surrounded by many square miles of flat, dried mud and with stark mountain ranges at either side.

Borough of Broxbourne: The Borough of Broxbourne is a local government district and borough in Hertfordshire, England.  Its council is based in Cheshunt, other towns include Broxbourne, Hoddesdon and Waltham Cross.  The eastern boundary of the district is the River Lea.  The borough covers 20 sqmi in south east Hertfordshire having a population of about 96,000.

Kathiawar Agency: The Kathiawar Agency, on the Kathiawar peninsula (Saurashtra lying between 20° 41′ and 23° 8′ N. and 68° 56′ and 72° 20′ E.; extreme length about 220 miles, greatest breadth about 165 miles, area about 23,445 square miles, and its 1001 population 2,645,805) in the western part of the Indian subcontinent, was a political unit of some 200 small princely states under the suzerainty of the Bombay Presidency of British India, now part of Gujarat state.  About 1,245 square miles, with 173,436 persons, belonged to the Gaikwar; about 1,298 square miles, with 128,559 persons, to Ahmadabad District; about 20 square miles, with 14,614 persons, to the Portuguese possession of Diu; while the vast remainder (area 20,882 square miles and population 2,329,196) was the territory forming the Political Agency.

Microclimate: A microclimate is a local set of atmospheric conditions that differ from those in the surrounding areas, often with a slight difference but sometimes with a substantial one.  The term may refer to areas as small as a few square meters or square feet (for example a garden bed or a cave) or as large as many square kilometers or square miles.  Because climate is statistical, which implies spatial and temporal variation of the mean values of the describing parameters, within a region there can occur and persist over time sets of statistically distinct conditions, that is, microclimates.  Microclimates can be found in most places.

Minsterley: Minsterley is a village and civil parish in Shropshire, England.  In the 2011 census, its population was 1,777.  Minsterley lies one mile south-west of Pontesbury and 10 miles south-west of Shrewsbury.  East from Minsterley along the A488, is the larger village of Pontesbury and to its south the hill range, the Stiperstones.  The Rea Brook flows nearby and the smaller Minsterley Brook flows through the centre of the village.

Turnford Brook: Turnford Brook is a minor tributary of the River Lea.  The brook flows through the Borough of Broxbourne for approximately 3 mi .

Spital Brook: Spital Brook is a minor tributary of the River Lea which rises in Hoddesdonpark Wood in the county of Hertfordshire, England.  Spital Brook flows eastwards from Hoddesdonpark Wood, passing through Barclay Park, the former Hoddesdon Common, on its journey to the Lea, while an unnamed parallel stream to the south has been diverted to form ornamental waterbodies located within the former parkland of Broxbournebury.  The stream crosses the Roman road, Ermine Street, before going under the A10 and Cock Lane.  The original crossing place or ford of Spital Brook in Cock Lane remains and the original route it took ran parallel to the brook in a north-south direction.  The brook passes through its namesake area, Spital Brook and marks the traditional boundary between the two parishes of Hoddesdon and Broxbourne.  The stream runs parallel to the Lea Valley Lines by Broxbourne Station until it meets the River Lea close to Broxbourne Riverside, the former Broxbourne Lido.

Bradfield, Norfolk: Bradfield is a village within the civil parish of Swafield , in the English county of Norfolk.  The village is 7.6 mi south south east of Cromer, 18.1 mi north north east of Norwich and 135 mi north east of London.  The village lies 3.1 mi north north west of the town of North Walsham.  The nearest railway station is at Gunton for the Bittern Line which runs between Sheringham, Cromer and Norwich.  The nearest airport is Norwich International Airport.  As with some Norfolk villages, Bradfield stretches across many square miles and merges into other villages on the edges.Bradfield Cricket Club has roots dating back to the late 1800s when a group of farm workers were allowed to play cricket on one of Bradfield Hall Farm fields.  Over the years the ground has developed and now boasts one of the best playing surfaces and outfields in the whole of the Norfolk Cricket Alliance

Greasby Brook: Greasby Brook is a tributary of Arrowe Brook, in Wirral, Merseyside.  The brook starts near to Dawlish Road in Thurstaston.  The brook flows through Thurstaston Common and around the western side of Greasby, before converging, firstly, with Newton Brook, and then with Arrowe Brook between Greasby and Saughall Massie.  Arrowe Brook then joins the Birket at Moreton.  The Birket, in turn, discharges into the West Float at the site of the former Wallasey Pool.

Supporting paragraphs: Turnford Brook Borough of Broxbourne
Answer: 20 sqmi