Monroe County public health officials may have found a better way to determine if and when the county's beaches should be closed to swimming.

The county has long used a model that considers several factors, including recent rainfall, algae levels, the Genesee River's flow into Lake Ontario, and water cloudiness. The model has been refined over the years, officials say, but there are still times when the beaches are closed unnecessarily.

But in 2010, county health officials began working with the US Geological Survey to develop a new, computerized model. Last month, the USGS released a report showing that during the 2012 beach season, the computer model was considerably more accurate than the county's existing model.

"Nowcasting," as it's called, incorporates a range of variables and uses real-time data pulled from weather data systems or entered into a computer or device at the beach. The computerized model analyzes the data and makes recommendations whether to close the beach, says Brett Hayhurst, a hydrologist at the USGS office in Ithaca.

Charlie Knauf, environmental health project analyst for the Monroe County Department of Health, says initial results from the model are promising. It has the potential to help health officials avoid unnecessarily closing a beach to swimming, he says, or leaving it open when it should be closed.

"We would minimize the risk to the public and maximize the recreational opportunity," Knauf says.

But the switch needs the approval of the local Board of Health and the county administration. Knauf says he wants to present the nowcasting system to the board at the end of the winter.

The local Board of Health may choose to implement the system, Knauf says, or it may opt for another year of side-by-side comparisons.