Assessment of the EIS for Chatfield Reservoir Storage Reallocation regarding Amphibians and Reptiles

[Note added by SaveChatfield.org: On August 2, 2012, Joe Farah, the senior author of A Survey of the Reptiles and Amphibians of Chatfield State Park, gave a talk to a group of citizens concerned about the Chatfield Realloacation Project. Joe began his talk by noting that Appendix F (Species of Mammals, Birds, Reptiles, and Amphibians Known to Occur in the Project Area) of the Chatfield Reservoir Storage Reallocation Draft Integrated Feasibility Report and Environmental Impact Statement, included five amphibian and reptile species that do not occur in Chatfield State Park:

• Great Plains Toad – Anaxyrus cognatus
• Plains Spadefoot Toad – Spea bombifrons
• Short-horned Lizard – Phrynosoma hernadesi
• Western Fence Lizard – Sceloporus occidentalis
• Prairie Lizard – Sceloporus undulatus

Worse, Appendix F failed to include four species that do occur in Chatfield State Park:

• Western Terrestrial Garter Snake – Thamnophis elegans
• Common Garter Snake – Thamnophis sirtalis
• Milk Snake – Lampropeltis triangulum
• Northern Leopard Frog – Lithobates pipiens

The Northern Leopard Frog is a Colorado Species of Concern! Its main strongholds in the park occur in the riparian zones along the Platte River and Plum Creek, areas that would be most affected by increased water levels.

Appendix F and the Draft EIS can be downloaded here.

What follows is an excerpt from Joe's talk.]

. . .

Because the EIS that was conducted for this project is extremely flawed and thoroughly unsatisfactory as it pertains to the amphibians and reptiles, I have put together my own short assessment of how this project will affect those species based on my personal study of the herps of Chatfield State Park that began in 2007 and continues to this day. The study is published online and available to the general public, including those conducting the EIS.

My personal assessment is as follows:

Amphibians

The riparian zones along the Platte River and Plum Creek serve as critical habitats and breeding grounds for all of the amphibians in Chatfield State Park. The Northern Leopard Frog, Western Chorus Frog, Woodhouse’s toad, Bullfrog, and the Tiger Salamander occur in these parts of the park. The Woodhouse’s toad is a versatile and durable species that is able to live and breed in a variety of habitats and will not be affected too badly by the inundation of these habitats. The Bullfrog is similar in that it is able to live and breed in almost any aquatic situation. The problem with the Bullfrog is that it is a non-native species and is regarded as a destructive force in the ecosystem which out-competes native amphibians for food, and breeding sites. It is also known to prey directly on our smaller native frogs. The proposed flooding and alteration of the riparian zones would provide the Bullfrog with a greater advantage over our native species by creating more habitat that is suitable for them, but not the leopard frogs or chorus frogs.

The three amphibian species that will be most adversely affected by the increased water levels and loss of riparian habitats will be the Northern Leopard Frog, the Western Chorus Frog and the Tiger Salamander. These species all have limited suitable habitat in the park and the main strongholds for all three of these species are the areas along the Platte River and Plum Creek where they empty into the main reservoir. These areas are expected to be completely underwater at times which will eliminate the only habitats that these species are currently known to breed and over-winter. All three of these species will be dealt a major blow if the proposed water level increases are carried out. I expect that the Tiger Salamanders which are only know to occur in low numbers near the King Fisher Bridge area will be wiped out and will disappear from the park completely. The Western Chorus Frogs will lose their most significant breeding site which is comprised of small, temporary pools in the area around King Fisher Bridge. When this area becomes flooded they will be reduced to a single breeding population in the park which is comprised of a few small ponds near the Audubon Society Building off Wadsworth Blvd. Lastly, the Northern Leopard Frog which is considered a Species of Concern in Colorado will lose its most important habitat which is along Plum Creek where it empties into the main reservoir. This area will be underwater and will no longer provide the small, weedy oxbow ponds that this species is uses for breeding and over-wintering. This habitat is critical because it does not favor Bullfrogs and has allowed the Leopard Frog to persist in the park in the presence the larger, more aggressive invasive species.

As I mentioned earlier, amphibians are an important part of the food chain and ecosystem and the effects of losing these species would ripple out to other species that many people treasure, and for which many people visit the park each year.

Reptiles

Chatfield State Park is home to diverse and healthy population of some of Colorado’s most iconic species of reptiles. The Western Painted Turtle, which was recently named Colorado’s State Reptile exists in several ponds adjacent to the main reservoir and would be threatened in several locations by the proposed water level increases. These turtles rely on smaller, calmer ponds with adequate basking sites and stable shore lines. These turtles are only documented in 4 ponds in Chatfield, two of which will be flooded and gone under the proposed changes. Snapping turtles are a rarely seen but important species for the health of Chatfield’s aquatic ecosystems. These turtles are more adaptable than the painted turtle and are able to live in the main reservoir, but because of the expected raising and lowering of the water levels, it is likely that many of their eggs will die from drowning as waters rise and flood their nests around the main reservoir.

Chatfield Park is home to no fewer than eight species of snakes, all of which will be hurt by the proposed changes. There are three species of garter snake in the park and all three are intimately tied to wetlands areas and the Platte River and Plum Creek. These species feed heavily on Leopard Frogs and Chorus Frogs which would diminish considerably from habitat loss. They also overwinter in densities along the Platte River which will be flooded and no longer available. It is possible that mass die-offs will occur because of the loss of over-wintering sites. Another snake species which will suffer from the loss and change of habitats is the well-known Bull Snake. This species occurs throughout the park in a variety of habitats, but is most prolific along the rivers and wetlands areas. Adults of this species feed heavily on young waterfowl and their eggs such as ducks, which will be reduced to fewer nesting areas because of habitat loss. Also, the muddy areas that are expected to be created by the raising and lowering of the water levels do not favor this species and they will lose considerable habitat along the main reservoir.

Another, even better-known species that I fear will be negatively impacted by this project is the Western or Prairie Rattlesnake. This species occurs almost exclusively in the narrow strip of grassy habitat between Wadsworth Blvd and the main reservoir. My concern here is that when the water level is increased, it will push the recreation areas along the western side of the reservoir back up into this species small slice of habitat and that will result in more encounters with humans. Because this species poses a legitimate threat to people and their pets, it seems likely that rangers will have to remove these animals when they are seen. Currently they exist in relative seclusion but as the available space for recreation shrinks between Wadsworth Blvd and the main reservoir, it is likely that people will be in more frequent contact with these snakes. Because of their very limited range, it is very possible that the species will become extirpated from the park.

Other snake species such as the yellow-bellied racer are unlikely to be dramatically affected, but most will suffer at least some degree of habitat loss, and the only affects that I am able to envision are detrimental.

Overall, the water allocation project will have negative effects on the amphibian and reptile species that live in Chatfield State Park. These effects range in severity from potentially disastrous, possibly resulting in the complete elimination of certain species from the park, to minimal, but I am unable to see how this project will do anything positive for any species other than human beings. Even then, many of us will suffer the loss of our cherished wildlife and beloved hiking, fishing and recreational areas. Hopefully my criticism of the EIS as it pertains to the amphibians and reptiles will encourage you and others to voice your own criticism of the project to those who have the ability to stop it from happening.

Thank you.

Joe Farah