ENVIRONMENTAL DOCUMENT AND
FINDING OF NO SIGNIFICANT AND NOT MORE THAN
MINOR OR TRANSITORY ENVIRONMENTAL IMPACT
[MCDV9802.EAF]
Modifications to Ongoing Hydrologic Data Collection in the
McMurdo Dry Valleys, Antarctica
I. FINDING
The National Science Foundation (NSF) has prepared an Initial Environmental Evaluation (IEE) and an Environmental Assessment (EA) as a combined environmental document, for modifying ongoing hydrologic data collection in the McMurdo Dry Valleys, Antarctica. Based on the analyses in the environmental document (IEE/EA), the NSF Office of Polar Programs (OPP) has determined that implementation of Alternative A is not a major federal action which would have a significant effect on the human environment, within the meaning of the National Environmental Policy Act (NEPA) of 1969. The action is not one which would have more than a minor or transitory effect on the antarctic environment, within the meaning of the NSF's implementing regulations for the Protocol on Environmental Protection to the Antarctic Treaty. Therefore, an environmental impact statement and/or a comprehensive environmental evaluation will not be prepared.
The selected alternative, A, provides for continuing hydrologic studies in the McMurdo Dry Valleys. In addition, new data will be collected about the movement of glacial snowmelt through the alluvium using temporary sampling wells, and an alternate stream will be identified to carry out tracer experiments in the event the flows in the Taylor Valley streams become too low. These modifications are consistent with the NSF's efforts to promote scientific investigations and improve data quality while protecting the antarctic environment.
/s/ Polly Penhale for II. PURPOSE AND NEED FOR THE PROPOSED ACTION
The National Science Foundation/Office of Polar Programs (NSF/OPP) proposes to modify the hydrologic data collection associated with the McMurdo Long-Term Ecological Research (MCM-LTER) project BM-042-M (formerly S-042M), now underway in Taylor Valley of the McMurdo Dry Valleys, Antarctica. The modification is two-part and includes placing temporary sampling wells in Taylor Valley stream channels and conducting a tracer experiment in Miers Stream in the Miers Valley (See Attachment 1 for locations).
Hydrologic data collection by the MCM-LTER program has been occurring in the Dry Valleys since 1990. Research has included stream gauging, relic stream reactivation, and stream tracer experiments. NSF/OPP has considered the environmental effects of these activities in previous environmental assessments: Continued Implementation of Hydrologic Investigations in the Dry Valleys, Antarctica – Project S-042 (1994) and Hydrologic Data Collection, McMurdo Dry Valleys, Antarctica (1995). The proposed work will provide quantitative measurements obtained under controlled conditions that can be used to develop models applicable to other areas within the Dry Valleys.
Sampling Wells in the Taylor Valley
The streams in the Dry Valleys are the major linkages between the glaciers and the lakes, and processes in the streams strongly influence how the lakes respond to changes in climate and meltwater inputs from the glaciers. The streams are comprised of two zones; the main channel with surface water flow and the hyporheic zone, which is the saturated zone underneath and adjacent to the main channel. Because the streams flow through sandy alluvium with high porosity, the exchange of water between the main channel and the hyporheic zone is rapid when compared with temperate streams, and the chemistry of the stream water is controlled by biogeochemical processes in the hyporheic zone (See Attachment 2). The lower limit of the hyporheic zone is controlled by the depth to the permafrost, which increases from 5 to 10 cm at the beginning of November to 50 to 60 cm at the end of January. Thus, the hyporheic zone increases in size and depth through the austral summer. Interactions between the main channel and the hyporheic zone have been studied by conducting tracer experiments and by collecting water samples from both zones.
Temporary sampling wells would be installed in the hyporheic zone at either Von Guerard Stream or Green Creek in the Fryxell Basin of Taylor Valley. These wells will be used to collect water samples from the hyporheic zone in January, before, during, and after a tracer experiment. The wells will be constructed of 2-inch polyvinyl chloride (PVC) pipe and will be screened at specified depths to collect water from that depth of the hyporheic zone. The wells will be installed in a line (transect) across the channel with 3-6 wells per transect. There will be 3-4 transects in the stream. The choice of streams will be decided based on the flow conditions; if it has been a cold summer with low flow then the wells will be installed in Green Creek, which is shorter and has a longer period of flow in cold summers than Von Guerard Stream.
The wells will be installed in the first week of January 1999. At this time, the hyporheic zone will extend to a depth of 45 cm. The transects will be located in a stream reach without many large rocks. The wells will be installed by drilling a 1.5 inch hole through the saturated alluvium with a hand auger. If a large rock is encountered while drilling, a new location will be chosen. The hyporheic zone material has the consistency of wet sand at this time in the summer. The wells will be sampled by pumping water with a hand pump, either a peristaltic or vacuum pump, and will be flushed before collecting the sample. The well casings will be removed at the end of January by pulling them out of the saturated alluvium.
Stream Tracer Experiments in the Miers Valley
Tracer experiments are used to determine the rates of hydrologic and biogeochemical processes in streams, and have been used in many temperate streams and twice in the dry valleys (Runkel et al, 1998, McKnight et al, 1998). The dry valley stream tracer experiments have involved injection of a conservative tracer solution (LiCl or LiBr) into the stream for a period of hours (3 hours in Huey Creek in 1992 and 1.5 hours in Green Creek in 1995). In addition to the conservative tracer, a reactive solute has been added to measure rates of biogeochemical processes. In Green Creek in 1995, K2HPO4 and NaNO3 were added and the rates of PO4 and NO3 uptake by the stream algal mats were measured. Both nutrients were assimilated by the algal mats, and there was no detectable increase in nutrient concentration at the outlet to the lake during the experiment. A follow-up experiment is planned for the 1998/99 season.
In the Taylor and Wright Valleys, the inter-annual variation in stream flow is large, as much as an order of magnitude between years. There is a possibility that the year for which the tracer experiment is planned will behave as a cold summer, with low flow. Further, because of the number of personnel needed to conduct the experiment, it is necessary to schedule the experiment as part of the SIP planning process. Previous tracer experiments have been conducted in Green Creek at low flow (12 L/sec) when Von Guerard Stream had already ceased to flow. In the 1997/98 season, the tracer experiment was cancelled because of low flow. Tracer experiments are not planned every year and represent a substantial investment of personnel and resources for the MCMLTER. Therefore, it would be useful to have an alternate stream site for conducting tracer experiments. The processes occurring in the hyporheic zone are generally occurring in all dry valley streams because of their common geomorphic features.
Issues related to the proposed actions include:
III. ALTERNATIVES
Alternative A: Continue hydrologic studies in the Dry Valleys and include the proposed modifications
Alternative A continues the data collection and field monitoring activities ongoing in the McMurdo Dry Valleys and includes installing the proposed, temporary sampling wells in the Taylor Valley and conducting tracer experiments in the Miers Valley in the event stream flows are too low in the Taylor Valley streams. As is required with the ongoing activities, results of the proposed actions would be evaluated at the close of the season and reported to the NSF/OPP. The report will include:
Alternative B: No Action.
In this alternative, no sampling wells would be installed in the Taylor Valley and no stream tracer study would be conducted in the Miers Valley. Only the actions currently planned by the MCM-LTER program and approved by the NSF/OPP would take place.
IV. ENVIRONMENTAL EFFECTS AND MITIGATING MEASURES
Sampling Wells
Physical impacts to the streambed
The installation of the wells will result in some disruption of the streambed from trampling by research personnel. There will be disruption from any unsuccessfully drilled holes, but these are expected to fill in as the wet sand slumps into the hole. There will be disruption from trampling when the wells are visited for sampling. There is a risk that it will not be possible to remove the PVC well casings at the end of January. The casings could become frozen into the hyporheic zone if a cold period occurs in the middle of January. If this is not followed by a warmer period then the casings would be frozen into the streambed.
The effects of trampling will be minimized by walking away from the stream banks and by approaching the wells on a temporary trail located perpendicular to the streambed. The trail and transects will be located so as not to disturb algal mats.
Duration of the sampling wells
The sampling wells will be used for one season and the casings will be removed at its closure. The hyporheic zone freezes from the surface down during the cold periods. The depth of this freezing will be monitored by the investigators to estimate whether the well casings may become frozen in by periodically probing the ground with a metal rod while they are on-site. If the ground becomes hard to probe, the casings may be removed earlier than planned. A ratchet device will be employed to make it easier to pull the wells out. If the cold period is very cold or sustained and the ratchet device does not dislodge the well casings, then the casings will be left in place and removed in early January during the subsequent season, when the hyporheic zone has thawed again. This activity will be incorporated into the regular stream flow monitoring program.
Long-term and cumulative effects
No long-term effects are expected. The holes would fill with wet sand after the PVC well casings are removed and the ground warms. No foreign materials will be left behind, and the ground will eventually return to its natural state.
Stream Tracer Experiments
Duration and frequency of tracer experiments
The impacts are associated with the establishment of a temporary field camp in Miers Valley and the helicopter support of the camp. The duration of the field camp will be 5-7 days, and the follow-up visits will be accomplished as day trips from the Lake Hoare camp. This will minimize the disruption associated with the temporary camp. The camp will be established at the site of the previous New Zealand huts in Miers Valley. This location will limit the spread of disturbed landscape. Any disruptions caused by helicopters will be minimized by using one, marked landing site. One tracer experiment would take place during any scheduled year and would last for a period of hours depending on stream conditions.
Location of stream where experiments are conducted
As previously discussed, the proposed tracer experiments would be conducted on Miers Creek in the Miers Valley in the event that flows are too low in the Taylor Valley creeks. The Miers Valley has been an area of active research in the dry valleys beginning in 1967. Research programs of the Japanese, Italian, U.S. and New Zealand programs have been conducted in Miers Valley. In the 1980s the New Zealand program conducted stream research in Miers Valley. Two stream gauges were installed, a V-notch weir and a flume, both made of wood. There is substantial information available about these streams. The climate in Miers Valley is milder than in Taylor Valley, and during the years of low flow in Taylor Valley there has been substantial flow (about 3 cfs or 70 L/sec) in the stream in Miers Valley.
Selection of constituents to be used as tracers and their concentrations
Only dissolved constituents naturally present in the streams will be used for the experiments. A solution containing a conservative tracer (LiCl or LiBr) and the nutrients nitrate and phosphate will be added within the hyporheic zone. Investigators will then follow the transport and biological uptake of the nutrients with respect to the tracers as they are exchanged in the stream channel. The concentration and duration of the tracer will be limited so that the input of the tracer is a small percentage (<1%) of the annual input of that constituent into Lake Miers. This will be determined based upon the stream flow in Miers Stream at the time.
Long-term and cumulative effects
No negative or long-term effects are expected. The quantity of tracer used will be insignificant compared to the average, total annual input to the receiving lake or stream. No known tracer experiments are planned by the USAP or any other national antarctic program working in the McMurdo Dry Valleys.
V. CONSULTATION WITH OTHERS
National Science Foundation/Office of Polar Programs
Antarctic Support Associates
INSTAAR:
REFERENCES
Environmental Assessment (Continued Implementation of Hydrologic Investigations in the Dry Valleys, Antarctica), 17 November 1994.
Environmental Assessment (Hydrologic Data Collection, McMurdo Dry Valleys, Antarctica), 14 November 1995.
APPENDICES OR ATTACHMENTS
MCDV9802.ATT.ppt is a Microsoft Powerpoint file that contains the following:
Dennis Peacock, Head
Antarctic Science Section
Ms. Joyce Jatko
Environmental Officer
Polly Penhale
Program Manager, Antarctic Biology and Medicine
Terry Johnson
Environmentalist
Diane McKnight
Principal Investigator for BM-042-M
In order to view these attachments, it would require downloading to your machine and calling up in Powerpoint.
Go to: