Tens of thousands of patients were waiting for routine treatment at United Lincolnshire Hospitals Trust in August, figures show.
The figures come as a leading health charity says the NHS is grappling with "really serious challenges", as typical winter pressures are to be made worse by the cost-of-living crisis and Covid-19.
NHS England figures show 71,266 patients were waiting for non-urgent elective operations or treatment at United Lincolnshire Hospitals NHS Trust at the end of August – up from 69,941 in July, and 50,800 in August 2021.
Of those, 7,166 (10%) had been waiting for longer than a year.
The median waiting time from referral at an NHS Trust to treatment at United Lincolnshire Hospitals Trust was 18 weeks at the end of August – the same as in July.
Nationally, 7 million people were waiting to start treatment at the end of August.
Siva Anandaciva, chief analyst at the King's Fund, a health charity, said the NHS is struggling with "crumbling buildings and outdated equipment, long waiting lists for care, high levels of Covid-19 and growing staff shortages."
"Successive governments’ refusal to confront the worsening health and care workforce crisis and their chronic underinvestment in NHS buildings and infrastructure has created this mix of problems.
"This winter, typical seasonal pressures on NHS services will be amplified by Covid-19 and a cost-of-living crisis that could impact on people’s physical and mental health," she added.
Separate figures show 1.5 million patients in England were waiting for a key diagnostic test in August – the same as in July.
At United Lincolnshire Hospitals Trust, 19,156 patients were waiting for one of 12 standard tests, such as an MRI scan, non-obstetric ultrasound or gastroscopy at this time.
Of them, 9,415 (49%) had been waiting for at least six weeks.
NHS Providers, which acts on behalf of health organisations in England, said the level of pressure across the health system "remains concerning".
It pointed to recent news of a shortage in blood supplies as creating delays for non-urgent operations.
Other figures show cancer patients at United Lincolnshire Hospitals Trust are not being seen quickly enough.
The NHS states 85% of cancer patients urgently referred by a GP should start treatment within 62 days.
But NHS England data shows just 55% of patients urgently referred by the NHS who received cancer treatment at United Lincolnshire Hospitals Trust in August began treatment within two months of their referral.
That was up from 51% in July, but down from 65% in August 2021 last year.
A Department of Health and Social Care spokesperson said: “This level of performance is not what patients expect and we must do better for them.
"The Deputy Prime Minister has set out her ABCD priorities – easing pressures on ambulances, clearing the Covid backlogs, supporting the care sector so patients can leave hospital and improving access to doctors and dentists.
“The public can support the NHS this winter by getting their flu jabs and Covid booster vaccines if eligible.”