River Tees Flooding & Flood Risk

The River Tees is one of the North of England’s most flood-prone rivers. It falls fast off Cross Fell in the North Pennines, then spreads across a wide, low floodplain through Barnard Castle, Croft, Yarm, Stockton and the tidal reach at Middlesbrough, and it carries a long, well-documented history of putting homes, businesses and roads under water. If you are bringing a site forward anywhere near the Tees, its flood behaviour will shape what the planners, the Environment Agency and your insurer expect from you. Unda’s flood risk consultants know this catchment well and prepare the flood risk work that goes with it. To talk a site through, call 01293 214444 or email enquiries@unda.co.uk.

No town shows the Tees’s temper better than Yarm. It sits inside a tight loop of the river, and on 31 January 1995 a Pennine cloudburst on top of melting snow drove the Tees clean over Yarm’s brand-new flood walls and down the High Street.

• A Pennine river with a wide floodplain. The Tees rises on Cross Fell and runs about 137 km to the North Sea at Teesmouth, draining roughly 1,800 km² through the Greta, Lune, Balder, Skerne and Leven.
• A designated Main River. The Environment Agency regulates the Tees for essentially its whole length, so the 8 metre byelaw margin and Flood Risk Activity Permits apply to work near it.
• Around 9,600 properties at risk. That is the number in the Tees catchment’s 1-in-100-year floodplain today, expected to rise to about 11,230 with climate change.
• Flashy at the top, tidal at the bottom. The river rises in hours off the moors, floods hardest at the meander towns, and turns tidal below the Tees Barrage at Stockton.

Check flood risk along the River Tees

The map below draws the River Tees in coral, with the Environment Agency’s live river gauges positioned along it, so you can click a gauge to see its latest level, its typical range and its record peak. Enter a postcode near the river to zoom in and screen that location against the Environment Agency’s flood data for rivers and sea, surface water, reservoirs and the flood zones used for planning. It is an indicative screening tool, not a flood risk assessment.

The River Tees in flood: a history

The Tees floods often, and the record is unusually well documented. The landmark event is still the flood of 31 January to 1 February 1995, when a sudden thaw in upper Teesdale met heavy rain over the Pennines. At Yarm the water reached the High Street and overtopped flood walls finished only two years earlier. At Broken Scar, above Darlington, the river hit 3.28 metres, the highest level on record there. The response was a strengthened Yarm scheme, its walls later raised by half a metre and fitted with more flood gates in 2002.

The year 2000 brought a run of floods in April, June, October and November. The June 2000 flood pushed the Tees at Low Moor, near Over Dinsdale, to 6.32 metres, still the record at that gauge, and water reached properties around Hartburn Avenue and Browns Bridge on the Stockton side.

The upper valley feels it first. At Barnard Castle the river runs fast and shallow off the moors, joined by Deepdale Beck on the town’s edge, and the riverside properties along The Sills, Thorngate and Bridge End are the first to be warned when Teesdale fills. Because so much of the catchment is steep upland, the Tees rises in hours rather than days, which leaves a short warning window and is exactly why the Environment Agency operates staffed flood gates at Yarm, Croft and Neasham rather than relying on walls alone. It is also why understanding flood return periods and annual probability matters so much on a river like this.

More recent storms have kept the pattern going. Storm Arwen closed the Yarm flood gates in November 2021 and put flood alerts on low-lying land such as the Teesdale Way at Croft. Storm Babet in October 2023 sent the Tees over its banks at Yarm again, with the gates locked around the High Street, and Storm Gerrit repeated the picture that December. Each event follows the same script. Heavy rain or snowmelt falls on the Pennines, the river rises fast through Teesdale, and the lower towns brace behind their defences.

Why does the River Tees flood?

The Tees floods because of what happens at its top end. The headwaters gather on the eastern flank of Cross Fell, the highest point in the Pennines, where annual rainfall tops 2,000 mm and the ground sheds water quickly. That gives the upper river a flashy, spate-driven regime: flows can climb past 100 m³/s during a Pennine storm and fall below 5 m³/s in a dry summer. High Force, where the Tees drops over the hard dolerite of the Whin Sill, is the visible sign of a steep, energetic upper catchment.

Cow Green Reservoir, built between 1967 and 1971 near the source, regulates the flow by releasing water in dry spells so it can be abstracted downstream. It was designed for water supply rather than flood storage, though, and it does little to hold back a major spate. Below the moors the river slows and meanders across a broad floodplain, and this is where the flood risk concentrates. Yarm sits inside one of the largest meander loops, and the wide, flat land around it has built natural levees over centuries of overbank flooding, a reminder of why floodplains matter to anyone developing near a river.

The tributaries add their own risk. The River Skerne runs straight through the middle of Darlington and joins the Tees just south of the town, so the same heavy rainfall that swells the main river backs the Skerne up through the built-up centre. It is a good example of why a riverside site here needs its flood risk read against both the Tees and its feeders, not the main channel alone.

• Broken Scar, above Darlington. Normally runs between 0.54 and 2.50 metres; reached its record 3.28 metres in the January 1995 flood.
• Low Moor, near Over Dinsdale. Drains 1,264 km² upstream, carries a mean flow of about 20.82 m³/s, usually sits between 0.31 and 4.50 metres, and peaked at 6.32 metres in June 2000.
• The Tees Barrage at Stockton. Opened in April 1995 between Stockton and Thornaby, it impounds around 18 km of former tidal estuary, holding a steady level above it and separating the freshwater river from the tidal reach below.
• A tidal lower river. Below the barrage the Tees is close to sea level, so flood risk there comes from high tides and surge as much as from rainfall.

Which areas does the River Tees put at risk?

The Environment Agency estimates that about 9,600 properties, along with key infrastructure, lie within the Tees catchment’s 1-in-100-year floodplain, a figure expected to rise to roughly 11,230 as the climate changes. Risk is not spread evenly. It clusters at the meander towns and the tidal lower reach. The Environment Agency runs discrete Flood Warning Areas for the most exposed communities and a catchment-wide Flood Alert for the lower river.

At Yarm the warning area covers the High Street and adjoining streets, Yarm School and Goose Pastures. At Barnard Castle it takes in Deepdale Gardens, Bridge End Flats along The Sills, Banners Mill and Thorngate. Croft, Neasham and Yarm all have flood gates that the Environment Agency closes ahead of a rising river. A site in one of these warning areas is very likely to sit in Flood Zone 2 or 3, which is what triggers the need for a site-specific assessment.

The lower, tidal river carries a different kind of risk. Stockton, Thornaby and Middlesbrough sit on low, largely clay ground beside the estuary, drained by a set of urban becks such as Marton West Beck, Ormesby Beck, Spencer Beck and Blue Bell Beck that were straightened, confined and culverted as Teesside grew. On sites like these the flood risk is a mix of the tidal Tees, surface water that struggles to drain off flat ground, and the becks themselves, which is why a drainage strategy usually matters as much as the flood risk assessment. If your site sits near any of these reaches, the town’s own flood story matters, and you can read more on our area guides for Darlington, Middlesbrough and County Durham.

Is the River Tees a Main River — and what that means for your site

The River Tees is a designated Main River for essentially its whole length, which puts it under Environment Agency control. That has direct consequences for anyone working near it. A Flood Risk Activity Permit is normally needed for works in, over, under or within 8 metres of a Main River bank, and the Environment Agency is a statutory consultee on planning applications the river affects. Many of the smaller watercourses that feed the Tees, such as the urban becks through Middlesbrough and Darlington, are ordinary watercourses instead, regulated by the lead local flood authority and by riparian owners rather than the Environment Agency. The distinction decides who you deal with and which consents you need: a Main River is the Environment Agency’s responsibility, while an ordinary watercourse falls to the lead local flood authority and the landowner.

For a development site, sitting near a Main River usually means a flood risk assessment is expected. A site-specific flood risk assessment shows the local planning authority and the Environment Agency that the development will stay safe for its lifetime, allowing for climate change, without pushing flood risk onto anyone else. Where the national flood maps are too coarse for a riverside site, that often means hydraulic modelling to pin down levels, and it can mean compensatory flood storage to replace any floodplain the development takes up.

On a Tees-side site that work runs through a familiar set of questions. It sets finished floor levels above the modelled flood level for the design event, adds the climate change allowance the Environment Agency now requires so the assessment holds good over the development’s life, and keeps access and escape usable when the river is high. It checks that raising one part of the floodplain does not push water onto a neighbour, and that surface water from the new hard surfaces is controlled rather than shed straight into the river. Get those points right early and they shape the layout; leave them late and they can force an expensive redesign or an Environment Agency objection. Our guide to when you need a flood risk assessment sets out the triggers in full.

Managing flood risk on the River Tees: policy and contacts

The Tees sits in the Northumbria River Basin District, and the Environment Agency’s River Tees Catchment Flood Management Plan sets the catchment-scale strategy, dividing the river into eight sub-areas by their flood character. Day to day, surface water, groundwater and ordinary watercourses are the responsibility of the lead local flood authorities the river passes through. North Yorkshire Council covers the upper and middle reaches around Croft and Neasham, Durham County Council and Darlington Borough Council hold the centre, and Stockton-on-Tees Borough Council and Middlesbrough Council take the lower tidal river. Each holds a Strategic Flood Risk Assessment that maps local flood risk in detail, and our town guides go into the local policy for Darlington, Middlesbrough and County Durham.

• Live river levels. Check the river’s gauges on the Environment Agency service (River Tees at Yarm and River Tees at Barnard Castle), the National River Flow Archive gauges at Low Moor and Broken Scar, or our own live river levels map.
• Screen a location. Try our free flood risk map, the ground conditions and soakaway map, and, for drainage design, the drainage calculators and BRE 365 infiltration calculator.
• Flood warnings. Sign up for Environment Agency flood warnings and call Floodline on 0345 988 1188. The River Tees at Yarm warning area shows how localised the service is.
• In a flood emergency. Call 999 if life is in danger, and 105 for power cuts.

How Unda helps with flood risk on the River Tees

We are flood risk and drainage consultants who understand how the River Tees behaves: the flashy Pennine response at the top, the meander flooding through Yarm, and the tidal risk below the barrage. We turn that into the reports a planning authority, a lender or an insurer will accept. We have prepared flood risk assessments and drainage strategies for sites across floodplains like the Tees, and we read each site against its own reach rather than a national map.

Our chartered consultants use the Environment Agency’s own modelling data and climate change allowances, engage the Environment Agency and the lead local flood authority early where a site needs it, and write in plain terms a planning officer can act on. If a clean, site-specific assessment can show your plot is safe, we say so and keep the report proportionate; where the risk is real, we set out the mitigation that makes the scheme work. If you are working on a site near the Tees, talk to one of our experienced flood risk consultants about what your application will need.

Flood risk and drainage services for sites near the River Tees

A development near the Tees can call for several different reports, and it helps to be clear that they answer different questions. A flood risk assessment, a sequential or exception test and a drainage strategy are three distinct reports. They often travel together in a planning submission, but they address separate things: whether the site is safe from flooding, whether the development should be located here, and where the surface water goes.

• Flood risk assessment for planning. The core report for a development near the Tees — see our flood risk assessment for planning service, framed by the NPPF and its planning practice guidance.
• Assessments for property purchase and insurance. Independent reports for buyers, owners and lenders through our flood risk survey for property purchase and flood risk assessment for insurance.
• Drainage strategies and SuDS. Surface-water design that keeps discharge within limits on flat, clay Teesside ground — see our sustainable drainage strategy and, at detailed design, the work to discharge a drainage condition.
• Sequential and exception tests. The locational justification the NPPF requires, through our sequential and exception test reports.
• BREEAM and groundwater. A BREEAM flood risk assessment for the Pol 03 credit, and a groundwater flood risk assessment where a high water table is in play.

River Tees flood risk: your questions answered