Until the summer of 2004 I never imagined that swimming pools, the source of countless hours of childhood fun, could be so deadly for frogs and other small animals. My interest in this issue stems from personal experience brought to my attention by friends.

In June of 2004 good friends, who had recently built an in-ground swimming pool on their wooded lot near Baltimore, Maryland, called to let me know frogs were dying in their pool. Nearly every day between one and several frogs and toads were removed from their pool - some were alive but others were dead in the skimmer basket. One morning, after a warm rainy night, an astonishing 53 frogs and toads were found in the pool. Of the 53 animals that were found, 18 were dead and 35 were still alive. Most of the live animals that were removed were obviously impaired from being exposed to pool chemicals. I spoke with other friends with swimming pools who also said frogs are regularly found in their pools. In addition to frogs, there was the occasional mole, mouse, baby bird, opossum, turtle, salamander, squirrel, bat, chipmunk, and more.

As a wildlife biologist, I found this information troubling and decided to find out more about this issue. I wondered if any research had been done on this topic. Is this a local issue or is it widespread? Did the animals die from drowning or from the chemicals?  In addition to the environmental impact, decomposing organic material (animals or their waste) uses up chlorine, raising the risk of chlorine lock, which is timely and costly to fix.  

A Google search turned up very little. A librarian with a science agency searched several scientific databases but could not find one paper addressing this issue.

How many frogs and other small animals are dying in a given year? The figure is likely at least 50 million but could be much, much higher. The number of beneficial insects, such as pollinators, that die in swimming pools is likely approaching a billion or more. The estimate is based on the fact that there were 4.6 million in - ground pools, 3.5 million above ground pools and 6 million spas (hot tubs) in the United States in 2004 (Association of Pool and Spa Professionals 2004). The estimate is derived from the number of in-ground pools times 10 animals for each pool plus another 4 million animals for the above ground pools and spas.

While the mortality figure is difficult to calculate with current information, the numbers of dead animals are likely increasing, as the swimming pool construction market is very strong. The unprecedented economic boom of the 1990s helped fuel what was probably the most robust growth period the swimming pool and hot tub industry has ever experienced. The statistics for new housing starts and new in-ground pool construction, track almost perfectly. (Association of Pool and Spa Professionals 2005).  Suburban sprawl suggests that the new swimming pool construction is happening closer to the natural habitats of amphibians and other animals making newer pools potentially even more harmful.  

The accounts from friends and others about this issue compelled me to try and do something. The products already on the market all had shortcomings.  One product was designed to clip onto an in-pool ladder rail - unfortunately many ladder rails attach to the deck outside of the pool wall so it would not work.  Another product was difficult to keep from falling into the pool. A third product was designed for larger animals, primarily pets.

We decided to build our own frog saving device, which became know as the Froglog. The Froglog was placed in our friend’s pool in early August 2004. For the first few days we did not find any dead animals in the pool; however, we could not tell how effective the device was since there was no way to know how many animals had fallen in. In addition, amphibian movement was slowing as the summer progressed and rainfall had decreased. To better document the efficiency of the Froglog, a funnel trap (similar to a minnow trap) was placed at the top of the device to catch all the animals that climbed up and out of the pool.

The Froglog was in the pool with the funnel trap for 23 days between August 14^th and September 9^th 2004. During this period, 47 American toads (Bufo americanus) and 3 green frogs (Rana clamitans) were removed alive from the funnel trap. Two dead American toads were found in the skimmer basket. During this brief test period, the Froglog was 94% effective at allowing trapped amphibians to climb out of the pool.

Since the results of this first test with the homemade Froglog were encouraging, six more Froglogs were built and given to other friends with swimming pools. The feedback was positive. One Froglog user, who was contacted in late August of 2005, stated that she had not found one dead frog or any other small animal since installing the Froglog at the beginning of the summer. Typically she would average six frogs a week in her pool early in the season.  Another user noted a drastic reduction in animals found in the pool and noted far fewer crickets and other bugs were found in the pool. One user of the Froglog figured out that turning the skimmer to cycle off at night was a key factor in allowing the animals to find the Froglog before getting drawn into the skimmer.

The summers of 2004 and 2005 were spent testing and modifying the Froglog. The Froglog went on sale to the public in the late summer of 2005. A patent is pending on the device.

The company is interested in working with the pool industry and conservation community on promoting pool owners to conserve native animals. The company is also looking to work with scientist to document and better understand this issue as little research has been done on this topic.   

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