The most common planning tool used in Connecticut, for the conservation of vernal pool habitats, is the seminal “Best Development Practices, Conserving Pool-Breeding Amphibians in Residential and Commercial Developments in the Northeastern United States” (2002), authored by Drs. Aram Calhoun and Michael Klemens. What was somewhat surprising, especially with the several vernal pools identified and inventoried at the subject site, that the Calhoun and Klemens BDP, as it is often referred to, was not utilized for this site. We have seen the BDP used by the applicant’s wetlands consultants on numerous other development applications in the past few years.
 

The BDP, as it is often referred to, provides recommendations for the conserving of vernal pool habitats, their hydrology, their water quality, and their obligate amphibian species, such as wood frogs and spotted salamanders. Perhaps the most often used tool regards the “critical terrestrial habitat” or CTH which is the are within 100 feet and 750 feet from a vernal pool. The recommended practice is to maintain or restore a minimum of 75% of the zone in contiguous (i.e., unfragmented) habitat, preferably forest. Manicured lawns, impervious surfaces and the like are not considered CTH habitat.

 

As can be seen in the attached figure produced by the applicant and annotated by REMA, neither of the two remaining vernal pools in the immediate vicinity of the proposed warehouse development will conserved and for slightly different reasons. First, we point out that our calculations are “conservative” because we included the first 100 feet (or the VPE, vernal pool envelope) in the CTH, which means that the percentages of disturbance with in the CTHs would be higher, by several percentage points.

 

Second, Vernal Pool 4 will suffer in the long-term, with a cascade effect to other vernal pools, especially Vernal Pool 6, due to the reduction of the populations from the impediment to migration and dispersal to be realized by the access driveway, with 24-7 heavy truck traffic. Reduction of breeding amphibians in Vernal Pool 4 will affect the physical characteristics of the wetland/pool system, degrading water quality (see additional discussion below).

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The elimination of Vernal Pool 7, with its robust spotted salamander population, will adversely affect the viability of Vernal Pool 6 and also Vernal Pool 4. Metapopulation dynamics play a very important role in the long-term sustainability of the vernal pool obligate amphibian populations. A metapopulation, which is the sum of the local amphibian populations that utilize the vernal pools, is very important especially since the high hydrologic variability of individual pools, some of which may dry up for several years during a sustained drought, are recolonized from those pools that remain wet during droughts.

 

Two factors come into play when considering metapopulation dynamics and the lost of Vernal Pool 7. One, Vernal Pool 7 is deeper, and can sustain sufficient hydrology for breeding during droughts, allowing for the recolonization of Vernal Pool 6, which has a much drier hydrologic regime. Two, with the elimination of Vernal Pool 7, and the physical barrier that would be in place due to the development, Vernal Pool 4, which has an intermediate hydrology between the other two pools, could no longer be a source pool for the recolonization of Vernal Pool 6. Over time, Vernal Pool 6 will cease to be a productive vernal pool, and just be an ecological sink. Eventually the vernal pool obligates will cease to breed here.

 

In conclusion, neither Vernal Pool 4, nor Vernal Pool 6 are considered “conserved” in the long-term, as the result of the proposed development. Alternatives should be sought that avoid filling Vernal Pool 7, while providing connectivity between these three vernal pools (i.e., VP4, VP6, and VP7).