The beach at Squantz Pond State Park, slightly north of Danbury, has been closed to swimmers because of the presence of blue green algae. The algae can emit toxins harmful to people and dogs. State environmental officials announced the state park\u2019s beach closing on Friday, before the weekend. Squantz Pond is essentially part of Candlewood Lake and in New Fairfield and Sherman. Officials are monitoring the waters to assess conditions and tests are being conducted on water samples from the Squantz Pond swim area to determine the level of toxins and when the area will be safe to reopen for swimming. The swimming area will be closed at least through the weekend. Indian Well open to swimmers Locally, testing shows the water at Indian Well State Park in Shelton is fine and it will be open for swimming this weekend. A complete list of water quality testing results at designated Connecticut state park beaches \u2014 showing which beaches are open and which are closed \u2014 can be found at www.ct.gov\/deep\/beachstatus. Storm water runoff is factor Blue-green algae, also known as cyanobacteria, occur naturally in lakes and ponds throughout Connecticut. These microscopic organisms often go unnoticed and cause no harm. However, when temperatures are high and high levels of phosphorus are carried into waters as a result of storm water runoff, a water body can experience nuisance blue-green algae blooms that may produce and release toxins. When blue-green algae blooms release toxins, people and pets using the water body for recreation can be affected. \u201cAs we do with all of the designated swim areas at state parks, the state Department of Energy and Environmental Protection will continue to monitor these waters and conduct tests to determine when it is safe to reopen the area for swimming,\u201d said DEEP Commissioner Robert Klee. \u201cAlthough the issue of blue green algae blooms is not new, there is now more research and understanding on the toxic effects of these blooms and public health concerns that they raise,\u201d Klee said. Can have negative effects People who recreate in waters when a blue-green algae bloom is present may be exposed to toxins by ingesting or inhaling water or skin contact. Potential health effects to such exposure could include: \u2014 Irritation of the skin, nose, eyes and respiratory tract. \u2014 Gastrointestinal upset such as vomiting or diarrhea upon ingestion. \u2014 Liver or nervous system effects, if relatively large amounts of the algae are ingested.