"We would like to see a little bit of transparency from the Environment Agency. This affects our lives, we want to make sure they do a proper job."
Dredging forms part of the Somerset Levels and Moors Flood Action Plan, commissioned by Environment Secretary Owen Paterson and made possible by additional Government funding.
The £100 million, 20-year plan to protect the Levels proposes a new tidal barrier at Bridgwater and raising the levels of key roads to prevent communities such as Muchelney being cut off again.
The start of the dredging follows months of extreme weather, which saw the country's largest pumping operation on the Somerset Levels and Moors.
Millions of tonnes of water were pumped off the Levels every day by 40 permanent and 25 temporary pumps.
The Environment Agency has insisted that dredging would not have prevented the flood crisis in Somerset, which left dozens of homes submerged.
But Mr Sadler said: "We expect flooding in Somerset but not for the extent and duration that we had this winter. If dredging on the rivers had been done, for example, Curry Moor would have been flooded for three weeks, not three months.
"Dredging would have made a huge difference. If the river had been wider and deeper, it would have taken a lot more water."
Flood waters in Somerset have only recently subsided, allowing residents to return home, roads to reopen and dredging to begin.
John Osman, leader of Somerset County Council, said: "We have contributed a significant amount of money to the pot for dredging and so we are extremely pleased to see the first dredging activity taking place.
"It is vital that our flood-hit communities know this activity is taking place to give them some reassurance, but dredging is only part of the solution. The Somerset Moors and Levels Flood Action Plan is key to reducing the risk of flooding in the future and we will work hard to win the funding necessary to deliver it."
Paul Leinster, chief executive of the Environment Agency, said dredging was part of a plan to help protect Somerset from future flooding.
"Today is an important milestone in the work to reduce the risk of flooding to people, property and land in Somerset and we welcome the additional money from Government that has allowed us to undertake this further dredging," he said.
"We are committed to dredging as part of the joint action plan, which includes other measures such as supporting farmers and making some temporary flood risk management measures permanent. We will continue to work closely with Defra, Somerset County Council and other partners to reduce the impact of future floods."
Some of the material removed by dredging will be used by the Environment Agency for flood bank repairs and construction to further improve "flood resilience" in the area.
Across the country, the Environment Agency is working to repair defences damaged over the past three months of extreme weather.
Around 6,500 homes and businesses were flooded in the crisis - though flood schemes protected more than 1.4 million properties and nearly 1,000 square miles of farmland.
