Officials say sewage overflow contaminated a Belmar beach's water with unsafe levels of bacteria, forcing its closure.

According to test results released Wednesday, bacteria counts at the "L" Street Beach came in well over twice the safe swimming standard.

The beach is not one of the major Atlantic Ocean beaches, it's a river beach on the Shark River, but it's the state's only closed beach right now.

The New Jersey Department of Environmental Protection says "sewage overflow from surcharging sanitary system discharged into storm drain" is the cause of the closure.

Test results taken over the last 10 days show a spike in contaminants found in the water. 

Swimming is banned in the water and could be for the next few days.

The contamination is measured by colony forming units, CFUs, or the concentration of bacteria in about 100 ml of water.

Normal and safe water for swimming has about 104 CFUs per 100 milliliters.

This beach had just 30 on May 21, spiking to 270 two days ago, nearly three times what's recommended.

The owner of one of the businesses along the river says health officials expect the sewage to wash out with the tide likely within the next few days.

Test results could be released later today that will determine when this beach is reopening.

New Jersey state officials perform weekly testing at 217 stations near public swimming beaches to identify potential bacteria hot spots.