Petrified Forest National Park Puerco sewage lagoons: Suggestions for rehabilitation; Final report

Nowak, Erika

Background Petrified Forest National Park Puerco Sewage Lagoons Suggestions for Rehabilitation Final Report February 2003 Erika Nowak, Wildlife Biologist USGS Southwest Biological Science Center Colorado Plateau Field Station, Box 5614 Northern Arizona University Flagstaff, Arizona 86011 (520) 556-7462 X 239 Petrified Forest National Park is currently undertaking a project involving the rehabilitation of sewage treatment facilities at several developed areas. One facet of the project includes installing vault toilets at the Puerco Pueblo Tour Stop. Thus, the sewage lagoons serving Puerco Pueblo will no longer be needed and are scheduled to be removed. The lagoons were originally installed near the Puerco River floodplain in the 1960's but never reached expected capacity use. Presently only one of the lagoons is active, and the other two are dry but occasionally hold water after precipitation events. These lagoons tend to retain water due to compacted soil and/or existing rubberized linings. To promote biodiversity in the park, management staff is interested in rehabilitating the area to provide more habitat for wildlife. Specifically, park resource managers and consulting biologists are proposing the creation of ephemeral wetland habitat (pools) from or around the old lagoons. Due to the current paucity of persistent breeding sites for amphibians in the park and to the importance of these animals as environmental indicators (Drost et al. 1999), we recommend that the sewage pond area be specifically rehabilitated to create two types of amphibian breeding habitats, and a secondary goal of this rehabilitation will be to provide an additional reliable water source for wildlife. Herpetofauna surveys were conducted at Petrified Forest National Park between 1997 and 2002 (Drost et al. 1999, Nowak and Hart 2002, Nowak 2002). All seven species of amphibians found in the park were detected within one mile north and south of the Puerco River and sewage lagoons. It is likely that all species occur here because this area at least occasionally contains two types of critical breeding habitats for amphibians. Ephemeral pools (defined in this report of having a hydroperiod of less than 30 days) are one type of important breeding habitat for amphibians in this area. This type of habitat, generally found in depressions in low-lying areas or artificial ponds, is scattered throughout Petrified Forest in average summer rain years (Drost et al. 1999). Species utilizing these pools, especially spadefoot toads, have fast larval development times, sometimes as little as three weeks from egg to terrestrial form (Woodward 1983, Wilbur 1987). At least one species of spadefoot toad (New Mexico spadefoot, Spea multiplicata) was found breeding in ephemeral pools immediately adjacent to the sewage lagoons during the surveys (Drost et al. 1999, pers. obs.). Plains spadefoot toads (S. bombifrons) were heard calling nearby in or near the Puerco River. A more rare type of habitat at Petrified Forest is relatively permanent breeding pools (defined as having a continuous hydroperiod of at least 60 days). Such pools are critical to the successful reproduction of species that take one to two months or more to develop from eggs into terrestrial forms, e.g. toads (Bufo spp.) and tiger salamanders (Ambystoma tigrinum) (Woodward 1983, Wilbur 1987). Regional draw-down of the water table and grazing-induced alterations of watercourses (e.g. Abruzzi 1995, Orodho et al. 1990) have likely decreased the availability of natural water sources to the point that amphibians with these longer larval stages now rely on artificial water sources for breeding (Drost et al. 1999, pers. obs.)....

Petrified Forest National Park Puerco sewage lagoons: Suggestions for rehabilitation; Final report

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