The Texas Conservation Plan has not slowed oil and gas well development in dunes sagebrush lizard habitat

Introduction

The dunes sagebrush lizard (DSL; Sceloporus arenicolus) is an imperiled species whose distribution is restricted to shinnery oak (Quercus havardii) sand dunes in the Mescalero Sandhills of eastern New Mexico and the Monahans Sandhills of West Texas, USA (Degenhardt et al., 1996; Fitzgerald & Painter, 2009). This area is within the Permian Basin, which is the focus of extensive and intensive oil, gas, and infrastructure development that degrades or destroys the species’ habitat (Sias & Snell, 1998; U.S. Fish and Wildlife Service, 2010). The species’ perilous conservation status has been recognized since at least 1982, when the U.S. Fish and Wildlife Service (FWS) first established S. arenicolus as a candidate for listing under the U.S. Endangered Species Act (ESA) (U.S. Fish and Wildlife Service, 2010). After episodes in and out of candidate status, the FWS proposed to list the species as endangered in 2010 (U.S. Fish and Wildlife Service, 2010). That proposal was withdrawn in 2012, in large part because of voluntary conservation agreements in New Mexico and Texas that the FWS believed offered adequate protections for the species (U.S. Fish and Wildlife Service, 2012).

The agreements for New Mexico and Texas are structured very differently, but both are based on the voluntary conservation component of section 10(a)(1)(A) of the ESA. For non-listed species, these include Candidate Conservation Agreements (CCAs) and CCAs with Assurances (CCAAs; for brevity, we refer to both agreements as the “CCA/As”). CCAs are agreements between FWS and one or more public or private parties that stipulate the actions enrollees will take or will avoid to conserve a species, which may preclude the need for listing under the ESA. CCAAs are similar to CCAs, but apply only to non-federal parties and include assurances that enrollees will not face ESA restrictions beyond those described in the CCAA if the covered species is listed in the future. (Federal agencies are not eligible for CCAAs because they cannot be exempted from the duty to avoid jeopardizing listed species under section 7(a)(2).) Parties in New Mexico drafted a CCA (for federal entities) and complementary CCAA (for non-federal entities) to protect lesser prairie-chicken (Tympanuchus pallidicinctus) and S. arenicolus habitat in December, 2008. These CCA/As include strong requirements to avoid the lizard’s shinnery oak sand dune habitats (U.S. Fish and Wildlife Service et al., 2008; U.S. Fish and Wildlife Service and the Center for Excellence in Hazardous Materials Management, 2008), which reflect the practices of the Bureau of Land Management in their Range Management Plan for the species (BLM, 2008). However, the CCA/As also direct oil and gas wells into interstitial habitats (between the large sand dune blowouts that the species uses) that provide connectivity among core dunes habitats.

In contrast to the New Mexico CCA/As, the Texas Conservation Plan (TCP) for the DSL—which is a CCAA with a tailored name—does not include avoidance requirements (Texas Comptroller of Public Accounts, 2011). Instead, the TCP offers only guidance to attempt to avoid habitat; there is no requirement for enrollees to avoid developing oil and gas wells in lizard habitat. Even though the same legal instrument underlies the agreement of each states—section 10(a)(1)(B) of the ESA—the differences in the details means we expect different conservation outcomes for S. arenicolus.

The objective of this study was to test whether voluntary conservation agreements for the DSL in New Mexico and Texas may have been effective at reducing oil and gas development in the species’ habitat. We hypothesized that the New Mexico CCA/As have produced a noticeable reduction of new oil and gas wells approval in DSL habitat, but that the TCP did not produce such a reduction. Our predictions were:

Methods

Results

The well data supported our predictions. We observed that the rate of new well approval was much lower within the DSL habitat than outside of the DSL habitat after the adoption of the CCA/As in New Mexico (Figure 1); however, the rate of new well approvals was no different inside versus outside of DSL habitat after the adoption of the TCP in Texas (Figure 2). The trends visible in the plots are supported by the generalized linear model statistics (Table 1).

Figure 1. The New Mexico Candidate Conservation Agreement (CCA) and CCA with Assurances (together, CCA/As), which have strong avoidance requirements, result in a rapid decline of new well approvals in dunes sagebrush lizard habitat after their adoption in 2008.

The plot shows the number of wells approved by the State of New Mexico per year (dots), inside and outside of the lizard’s habitat (yellow and purple, respectively). Fitted lines are from a simple least-squares model of the form number_wells ~ year + in_CCAA_area, split by pre- and post-CCA/A. Figure CC-BY Defenders of Wildlife 2018, available at https://doi.org/10.6084/m9.figshare.6226721 (Malcom & Moskwik, 2018).

Figure 2. The Texas Conservation Plan (TCP), which lacks strong avoidance requirements, has no apparent effect on new well approvals in dunes sagebrush lizard habitat versus outside of habitat after the TCP was adopted in 2012.

The plot shows the number of wells approved by the Texas Railroad Commission per year (dots), inside and outside of the lizard’s habitat (yellow and purple, respectively). Fitted lines are from a simple least-squares model of the form number_wells ~ year + in_TCP_area, split by pre- and post-TCP. CC-BY Defenders of Wildlife 2018, available at https://doi.org/10.6084/m9.figshare.6226964.v2 (Malcom & Moskwik, 2018).

Discussion

Conserving the DSL requires protecting its remaining habitat in both New Mexico and Texas: if the species is lost from either state then representation (Shaffer & Stein, 2000)—both in terms of unique genetic contributions (Chan et al., 2009; Chan et al., 2013) and geographical distribution—will be lost. Our analyses indicate that the CCA/As in New Mexico have significantly reduced oil and gas development, one of the most notable direct threats to the DSL and its habitat. In contrast to New Mexico, the data show that the TCP has had no effect on the rate of new well approval inside DSL habitat in Texas. This research highlights how the details of voluntary conservation agreements, even those authorized under the exact same provision of law, can lead to markedly different outcomes.

The decline in the number of new oil and gas wells approved each year in New Mexico after the CCA/As were adopted reflect the avoidance requirements in those agreements. The number of new wells approved in the DSL’s range in New Mexico is not zero since the CCA/As were enacted because the agreements allow well siting in interstitial habitat. While this reduces the direct effects of development, it likely harms connectivity (U.S. Fish and Wildlife Service, 2008) and may have secondary effects on landscape characteristics that influence DSL life history (Ryberg et al., 2015).

Because the TCP does not require avoidance of DSL habitat loss, i.e., there is no mechanism protecting the habitat, we expected to not see any effect of the TCP. The data supported our prediction, and even hint that the rate outside DSL habitat decreased faster than inside. Had the State of Texas incorporated strong avoidance requirements of the New Mexico CCA/As into the TCP, then our analysis may have shown that voluntary conservation efforts were sufficient to protect the DSL.

Data availability

In addition to obtaining the data as described in the manuscript, the raw oil and gas well data associated with this article can also be found on OSF: https://osf.io/hkvsu/ (Malcom, 2018).

Software availability

Software available from: https://github.com/jacob-ogre/DSL_well_approvals.

Archived software at time of publication: https://osf.io/hkvsu/ (Malcom, 2018).

License: BSD 2-Clause "Simplified" License.