Walton crews plug up outflows to protect dune lakes (PHOTOS and CNN VIDEO)

The beaches were buzzing with beach-goers Monday as bulldozers and dump trucks re-contour and plug up the flow between the area's coastal dune lakes and the Gulf of Mexico.

The dams are part of Walton County's Action Plan, which will "keep the oil from reaching the coastal dune lakes," said Ronnie Bell, of C.W. Contracting.

The action plan was approved by Florida's Department of Environmental Protection on Friday. Shortly after, large trucks carrying tons of sand could be seen travelling caravan-style through Grayton Beach. To see photos of the caravan, click here.

Crews worked throughout the weekend on area beaches and around the lakes.

The coastal dune lakes are a unique feature of Walton County. Some of the lakes are connected to the Gulf by narrow channels called outflows.

The outflows are being fitted with several defensive barriers. "The first line of defense," Bells said, is a narrow sand dam near the shoreline. Then a larger 5- to 7-foot-tall sand dam rises further away from the shoreline, followed by four layers of booming.

Western, Big and Little Redfish lakes are almost complete, he said. Camp, Deer and Eastern lakes were finished over the weekend.

The county may have seen its first sign of oil, in the form of "quarter-size clots" of tar balls on Friday and Saturday, according to a Sheriff's Office oil update.

Besides racing the clock to complete the project before oil comes ashore, all the children running around and not paying attention to the earth movers on the beach have the workers a little "stressed," said Billy McKee, environmental manager for Public Works divisions.

"It is hard to operate the machines in the sand," McKee said "So we are asking parents to watch children carefully around the heavy machines and give them plenty of room."

To see more photos of the weekend work on the beach and kids playing near the boom, click here.

To read a Kentucky TV station's report out of Seaside, click here.