Moves to build up to half a million new homes across the West Midlands are in danger of being pushed through with no regard to the dangers of building close to rivers and streams in a region notorious for flooding, a government watchdog claimed yesterday.

The Environment Agency said it was deeply concerned that a 20-year strategy to meet a housing shortage did not consider either flood risk or the practicalities of supplying the infrastructure necessary to carry water to the new communities.

Giving evidence on the opening day of a public inquiry into revisions to the Regional Spatial Strategy, Environment Agency regional sustainable development manager Sharon Palmer revealed that the West Midlands remains the only region in England yet to adopt a flood risk policy – even though millions of pounds worth of damage was caused by torrential downpours in Worcestershire, Warwickshire and Shropshire during 2007.

Ms Palmer said most people would find it “remarkable” that the spatial strategy, which sets out proposals for at least 365,000 new homes by 2026, did not take flooding into consideration and that specific policies to deal with water-related risks were unlikely to be developed until 2011.

She added: “We find it unacceptable that we have to wait for two years until such a policy appears in the spatial strategy.”

The West Midlands Regional Assembly, responsible for drawing up the spatial strategy, was behaving in a way that did not contribute to sustainable development, she said. The environment was being dealt with in isolation and not being considered alongside economic and social drivers.

The first session saw conservation groups hit out at the spatial strategy, in particular a move by the government to increase the number of new homes to 445,000 – almost twice the number currently envisaged.

Gerald Kells, regional policy officer for the Campaign to Protect Rural England, warned that green belt land was at risk of being swallowed up.

The West Midlands was in danger of losing both its “tranquillity and landscape”, two factors that made the region a place where people wanted to live.

Mr Kells said the spatial strategy started from a position of sanctioning an unrealistic number of new homes and then attempted to identify sites for development while “optimistically assuming intractable environmental and infrastructure issues can be resolved”.

The review of the spatial strategy relied too much on a mechanistic approach to housing numbers with inadequate consideration of how the provision of infrastructure would be funded.

The result, he warned, would be to encourage building new housing in rural areas which would lead to more population migration from West Midlands cities to the countryside.