THE FOREST SERVICE'S BLACK RIVER LAND EXCHANGE AND GROUNDWATER: DATA, LACK OF DATA, AND THE NEPA PROCESS

Very often an environmental document must be completed with less than adequate data. This shortcoming is not always obvious at the time. However, public response to these documents may make the omission abundantly clear.

The Black River land exchange could result in a housing development on the private land of 258 single family homes in a sparsely populated area near Greer, AZ. The NEPA process progressed and an EA was prepared, and the reasonably foreseeable development scenario studied involved pumping the Coconino, or C aquifer with a single well at the rate of 200 gpm. In support of this, a report was prepared which included a Theis analysis, concluding that impacts would be minimal.

The Forest Service (FS) was sued by environmental groups over the perceived inadequacy of the NEPA process. The proponent also argued that costs of pumping from C aquifer depths would be prohibitive. U.S. District Judge Murgula ordered that the FS analysis should have included the effects of pumping the local shallow aquifer with 258 individual wells and that an EIS should have been prepared.

In response to the court order, R.D. Congdon prepared a modeling report showing potential impacts of pumping from 258 shallow wells. No data was available for the shallow aquifer, so a range of hydraulic parameters was used to demonstrate the potential effects. A total pumping rate of 80 gpm was applied; 0.31 gpm per lot. Conceptual analytical and MODFLOW models were utilized. The Draft EIS was released to the public and comments about modeling without data were submitted by informed citizens and groundwater professionals.

In order to effectively respond to the criticism, it was necessary to obtain some local hydraulic conductivity (K) data. A contractor was employed by the Forest Service to conduct three slug tests in the water table aquifer; one at a FS well and two at private wells. The data showed an average K of 13.4 ft/d. The modeling report was amended with this data to refine the predictions. This made completion of the Final EIS possible.

Land exchange proposals in the arid southwest are now facing tough groundwater questions from an anxious public. Much time and energy may be spared by obtaining aquifer parameters in the beginning which enables the preparation of reports that may withstand these new challenges.