Nearly one third of neglected and abused children in Lancashire are already at risk of significant harm by the time social services step in.
The Local Government Association warns that "huge increases" in demand across England have outpaced funding, putting vulnerable youngsters and their families at risk.
The latest Department for Education statistics show 15,415 children were judged to be in need of support after being referred to the council's social services in 2018-19 – equivalent to 62 in every 1,000 young people.
Of these, 31 per cent were made the subject of a child protection enquiry, which the British Association of Social Workers says indicates a juvenile is at crisis point.
This compares to none when records began in 2009-10.
Mental health was the most common concern for children referred to social services, mentioned in 63 per cent of assessments, followed by domestic violence, which featured in 59 per cent.
Social workers may record more than one factor during an assessment.
Councillor Judith Blake, chair of the LGA's children and young people board, said: "Councils want to make sure that children can get the best, rather than get by.
"Yet funding pressures are coinciding with huge increases in demand for support because of problems like hardship and family conflict, which is making it increasingly difficult for them to do that.
"No family is immune to life's challenges, and every family should feel safe in the knowledge that if they need it, help is there to get things back on track.
"If councils are to give children and families the help they need and deserve, it is vital they are fully funded. This is not just children's services, but the breadth of support councils can provide, from public health to housing."
Families of youngsters in need may simply be given advice or referred to services that can help, such as counselling or after-school clubs.
But when social workers suspect a child is suffering or is at risk of harm they will make what is known as a Section 47 enquiry, to determine if they need to intervene.
If they conclude the child is at risk, they must then decide whether to put a protection plan in place.
In Lancashire, 19 per cent of vulnerable children were under protection plans during 2018-19, compared to six per cent nine years earlier.
By law, the measures must be reviewed within three months, and once every six months after that.
But reviews were not carried out in time for five per cent of the area's 937 youngsters subject to a plan for longer than three months.
Across England, the number of children referred to social services and seen by a social worker rose slightly, from 705,000 in 2017-18 to 708,800 in 2018-19.
Fewer children are now subject to protection plans, at 52,300 – down three per cent from last year.
A government spokesperson said: "We are working to strengthen families and tackle the causes of need – from mental health and addiction to domestic abuse. We are also providing an extra £1 billion for local councils to deliver social care.
"We are also cracking down on exploitation of young people by criminal gangs and supporting councils in their duty to care for unaccompanied asylum-seeking children, alongside providing more investment in mental health support."