Inspectors have warned a budget-cutting council against reducing education spending given that a quarter of its schools are underperforming at key stages 1, 2 and 3.
The inspection agency Estyn has praised support for school improvement in Powys, but says the authority must address falling achievement in all three key stages. It has also warned that budget cuts should be avoided to help schools meet the challenge.
Powys is planning a 2.5 per cent cut to the delegated schools budget in 2006-07, prompting threats of industrial action by the classroom union NASUWT Cymru to protect jobs.
Geraint Davies, its secretary, said: "According to Powys's own estimates, that would lead to the loss of 70 jobs. Such swingeing cuts would also badly affect the standards agenda, and Estyn's report underlines that even further."
Last year, Powys was in the top four local authorities for all key improvement indicators, with pupils performing above national averages for a number of years.
But in a report on the council's school improvement work, Estyn has criticised the "unsatisfactory performance" of just over a quarter of schools at KS1-3, saying they do not match the achievement of similar schools elsewhere in Wales.
Inspectors said there were:
* more schools than expected in the bottom quarter in KS1 and 2, and in the proportion of pupils gaining five A*-G grades at GCSE
* more schools than expected below the median in KS3; and
* fewer schools than expected in the top quarter at KS3 and in the proportion of pupils gaining five A*-G grades at GCSE.
The council said it will prepare an action plan for improvement but that much of the action needed has already been taken.
Councillor David Jones, board member responsible for schools, said: "We have accepted the recommendations and will use the findings to strengthen an already successful service."
Overall, the LEA was praised for its support for school improvement, having a clear strategy, an effective system for monitoring the work of schools, and for targeting those in greatest need of help.
In 2003, two Powys schools were found to have serious weaknesses but have been removed from the list. The report says heads rate highly the quality of the authority's support, while leadership of the service was said to be strong. But Estyn said secondaries get less support than primaries, and underdeveloped scrutiny procedures need attention.