Toby HullSouth East Rivers Trust

March 2015

The Constraints of Connecting Habitat and Fish Passage in an

Urban Environment

Outline

• Introduction to the Hogsmill River• Introduction to the CRF Project• Constraints encountered with the project (challenges)• Solutions and Outcomes (opportunities)• Conclusion

Hogsmill River

- Urban catchment in South London- Joins the Thames at Kingston- 1st non-tidal tributary of the Thames- 6.5 miles long- Technically a chalk stream (but flashy

urban characteristics)- Poor water quality - Appeared in Millais’ “Ophelia”

Hogsmill River

Hogsmill River

Hogsmill River

- Highly modified channel- 15 obstructions between the source

in Ewell and the Thames at Kingston- Fragmenting already heavily

degraded habitat- WFD status – Poor with Fish and

Macrophytes driving classification

CRF Hogsmill River Connectivity Project

Aim: To provide fish passage along the entire river in order to improve WFD status towards

achieving Good Ecological Potential (GEP)

Objective: Removal or modification of all obstructions/barriers to passage and

connectivity

£350k

Flood Defence & Historic Relics

Bridge Footings

Utilities

Spatial Constraints

Spatial & Flood RiskConstraints

GaugingData

“if it can be thought, it can be done,

a problem can be overcome” E. Bucchianeri, Brushstrokes of a Gadfly

Where there’s a will (& some money) there’s a way…

Different solutions, different ways of delivering:

Contractors, in-house, volunteers

• Flood Risk (real or perceived)• Surrounding Land Use

• Utilities• Bed & Bank Stabilisation• Migrating Knick-Points

Constraints = Compromise

Rock Ramp

Concrete

ConcreteConcreteConcrete

Concrete

Concrete

Concrete

BeforeClose-to-Nature Pool PassAfter

Baffles

Composite Solution

Additional Benefits

Additional Benefits

• Habitat Improvements• Flood Risk Reduction

• Water Quality Improvements• Partnership Working• Community Interest

Additional Benefits

Lessons Learnt

“There are no secrets to success. It is the result of preparation, hard work and

learning from failure” Colin Powell

“Failure is success if we learn from it” Malcolm Forbes

Summary• There are a lot of constraints…

Irremovable Structures

Utilities/Services

Surrounding Land UseSpatial Channel MorphologyFlood Risk

AccessRiver Characteristics (flow regime)

Working ‘wet’ in-channelWeather

Knowledge

Public Perception (‘waterfalls’)

Flood Risk (perceived)

Fish Swimming Capabilities

TimeData Collection

Budgets

Infrastructure

Summary• There are a lot of constraints…

• But persevering, we’ve always found a solution, even if there is compromise

• This may mean that we concentrate on fish passage and not full connectivity but this does move the river towards GEP (being as good as it can be within the constraints).

• We’ve learnt a lot along the way and have had lots of help from others

• Also had lots of fun along the way!

Thank you for your attention