MADISON, Wis. — Algae blooms have forced health officials to close five Madison-area beaches.

The Wisconsin State Journal reported Friday that the first tests of the season revealed blue-green algae blooms at beaches at BB Clarke, Olbrich and Warner parks and the Hudson Park lake access point. Health officials also have closed Fireman's Park in Verona as a precaution although regular monitoring hasn't started there yet.

Public Health Madison and Dane County, the city-county joint health department, is urging swimmers to check conditions before entering the water at any beach since algae levels can change quickly.

Blue-green algae blooms can make both pets and humans sick and can create dead zones in lakes after consuming all the oxygen in the water, killing off much of the remaining aquatic life.

The blooms result from fertilizer running off lawns and farm fields into lakes, ponds and rivers.