GIS Analysis of Cove Wash for Potential Adverse Contamination from Uranium Mines

 

 

(Photos by USACE, 2000)

 

 

1.0 Introduction

 

In 2005, the first tribal law to ban uranium mining on tribal lands was ratified on the Navajo Nation.  This legislative action is an initial step by the tribe to identify issues resulting from mining practices.  Water quality is one of the appalling issues rising for the need of water resources remediation.  Accordingly, this report will assess water quality for a study area along the Cove Wash where radioactive constituents were detected in the streams and wells downstream from abandoned uranium mines in northeastern Arizona.

 

2.0 Objective

Over a course of 30 years, Cove Chapter advocated for the health of the miners, millers and their families but today they strive to restore their water resources that support their way of life.  Five of the water sampling sites will be analyzed using the ArcGIS spatial analysis tools to understand the distribution of radioactive elements downstream near the irrigable tracts in Cove.  This report aims to reveal the need for potable water which will contribute to other issues if the contaminated water resources are not dealt with timely. 

 

3.0 Methods

 

The water quality data was compiled from two sources: the Army Corps of Engineers Los Angeles District archives and the Navajo Water Quality website.   The sampling data was entered into the Microsoft Excel spreadsheet and then converted into a DBF file to establish the sampling points as a vector data (*.shp).  The Navajo Nation boundary was downloaded from the U.S. Census Bureau website.  The mines, streams and State Soil Geographic (STATSGO) data were acquired from the Southern Arizona Data Service Program website.  The STATSGO coverage was clipped to study area polygon, and its attribute table was related to the following tables using the map identification number (MUID): component, woodland, forest and plant communities.  Five 10m digital elevation models (DEM) were downloaded from the Arizona Regional Image Archives (ARIA) and then mosaiced using the Raster Calculator.   The mosaic raster was clipped using Cove boundary (*.shp) into a rectangle array of cells and then converted into a hillshade using the spatial analysis tools.  Furthermore, the fill, flow direction, flow accumulation, streamlink and watershed grids are applied for surface analyses.  Each GIS data are projected using the NAD 1983 - UTM Zone 13N Geographic Coordinate System.  The 1997 orthoimage of the Cove community was obtained from the Terra Server website using the Photoshop at the Map and Geographic Information Center.  The grids and aerial will be use to analyze the land use in the selected area.

 

4.0 Background

The arid terrain of Cove is a prime sedimentary deposit for uranium ore and other radioactive metals.  These sandstone uranium deposits are found near the surface and explain why it is preferred mining rather than the other depository with minimal innovation.  Cove community endured uranium mining activities from the late1940’s thru late 1960’s when the mining companies established to supply uranium and vanadium to the U.S. nuclear weapons program during the Cold War (Shuey and Brown, 2004).  Only 32 uranium mines on the rugged terrain west of the Cove are identified as Geographic Position System (GPS) reference points by the Bureau of Mineral Mine (Southern Arizona Data Service Program, 2004) (MAP 1).  However, the Navajo Abandoned Mine Land Reclamation Program (NAMLRP) identifies 229 uranium mines in Cove (Richardson, 1991).  These mines were abandoned exposing levels of radioactivity when the uranium mining companies declared bankruptcy.  In 1995, the NAMLRP was given the task to reclaim the uranium mines across the reservation.  The NAMLRP Shiprock field office has reclaimed 95% of the mines west of Cove after more than 35 years of exposure but a number remain open in the area near or at the mesa cliffs (Yazzie, 2006).  The NAMLRP recommended reclaiming the mines but were not primarily concerned with the water resources adjacent to the mines. The NAMLRP GPS data of reclaimed mines was not immediately available.

 

5.0 Results

The study area is approximately  3.8 square miles (2432 acres) where five water samples were collected by the U.S. Army Corp. of Engineers in 1999: Chapter House, Well 309, Area 4, Area 1 and Pipe Mine (MAP 2).  Another well (maroon dot on the map) was drilled by the Navajo Tribal Utility Authority (NTUA) but capped it after testing for radioactive constituents posing health risks to the community.  The headwater of Cove Wash begins southwest of Cove Chapter near the reclaimed and open uranium mines on the northeastern end of the Lukachukai Mountains.  The Area 4 is located about 1.45 miles up gradient of Well 309 and downstream from the Pipe Mine at the confluence of the two northern tributaries.  The spring, rain and snow runoffs feed Cove Wash which perhaps trickles even in late summer.

X

Y

Units

Structure

Elevation

Field Type

109.19

36.58

Meters

Cove Chapter

5,998

Well

109.22

36.56

Meters

Well # 309

6,305

Well

109.23

36.54

Meters

Area 1

6,481

Stream

109.23

36.54

Meters

Area 4

6,522

Stream

109.25

36.53

Meters

Pipe Mine

7,404

Mine

         Table 1: GPS Reference Points of sampling sites (U.S Army Corps of Engineers, 2000).

5.1 Analysis of Water Quality

The U.S. Army Corps of Engineers (USACE) conducted water quality assessment of several mining districts on the Navajo reservation.  Cove Chapter is part of the Four Corners district where the USACE collected 17 water quality samples from streams, windmills, mines, springs and wells in 1999 (US EPA, 2000).  The Geiger Lab tested the water samples for radioactive elements at Northwestern University.  The following charts list six of the radioactive elements traced in the water samples from the study area:

Radioactive Elements (picocuries/liter)

Location

Lead

210

Radium

226

Radium

228

Uranium

234

Uranium

235

Uranium

238

Chapter House

.50

1.46 *

.591

.09*

0.0*

0.0*

Well # 309

.97

.441*

.651

45.0

.707*

38.0

Area 1

.24

1.59*

.2154

26.0

--

51.31

Area 4

.34

2.93*

.644

74.6

3.130*

71.1

Pipe Mine

11.7

14.4

.636

36.6

2.25*

28.9

EPA Standards

.047

5.0

.21

20.0

20.0

20.0

                                    Table 2: Water Quality Data (Navajo Water Quality Monitoring, 2004).                   

                                     *No sufficient health risk

                                    -- No data

 

The Uranium 235 and 238 isotopes are above the Maximized Contamination Level required by the EPA water quality standards at the four sampling sites upstream of the Chapter House.  These radioactive elements are known to be carcinogenic and responsible for kidney damage. The USACE reports a high health risk for human consumption at these sites, both stream and well.  The test also indicates the radioactive constituents are possibly moving downstream toward the Cove community.

 

5.2 Analysis of Land Use

            The vegetation and watershed are considered to determine land use within the study area.  The irrigable tracts are located downstream of the (stream) sampling sites, Area 1 & 4, near Well 309 along Cove Wash (MAP 3).  An estimated 12.7 acres of irrigable tracts represents much of the land use that generates sustenance and cash crops like corn and hay.  These fields are irrigated by snowmelt and precipitation runoffs into Cove Wash from higher elevations where reclaimed and open mines exist.    The two community schools and several residences are located on the east end of the tracts which all use water services provided by the NTUA.

In general, there are two types of vegetation cover: shrub/grassland and mixed woodland (MAP 4).  The shrub/grassland covers majority of the study area that is used as rangeland if not irrigated.  The mixed woodland is composed of pine, juniper and pinyon at higher elevations.  The irrigation is occurring near the transition line of the vegetation between the two stream sampling sites but the shrub/grassland is ideal farming area.

The watershed grid with flow accumulation show three sub-watersheds that contribute runoff flows into Cove Wash (MAP 4).  Two of these sub-watersheds are located at the headwaters of Cove Wash.  The flow accumulation illustrates the flow is downstream which is represented by gradation of blue line (darker blue = higher accumulation flow) within the brown colored sub-watershed.  The irrigation tracts are situated within the brown colored watershed.  Finally, the NTUA capped well and Well 309 are located in different sub-watersheds which explain there is definitely a link between the surface water and groundwater.  However, a hydrologic assessment of the catchment is required to examine the surface and sub-surface flows to determine how water in different sub-watersheds mix to produce radioactive compositions along Cove Wash within the selected area.

 

6.0 Conclusion

The analyses of water quality and land use demonstrate a glimpse of the potential adverse water sources in the study area.  For that reason, these sources must be delineated and monitored in order to ensure the EPA water quality standards for human consumption are met.  In addition, the monitoring will also improve water available for agriculture and wildlife.  If contaminated water infiltrates into the soil, the vegetation uptake the water, then it is grazed by livestock and wildlife, and used by the community for communal gatherings and rituals.  This cycle must end to restore the communal health of Cove by ensuring potable water.

 

Future Work

The Cove water quality needs to be addressed.  For further assessment, the communal water uses should be defined other than water utility services.   A communal participation is highly recommended to observe water quality of natural springs and streams in the area.  Accordingly, the community members should identify their water source(s) that they use for domestic and agriculture.  Therefore, a plan for water quality monitoring can be developed to provide the community better access to potable water.

 

Acknowledgements

Thanks to Mr. Glynn Alsup of USACE for sharing the Cove water quality assessment data.

 

Data Dictionary

 

 

Data

Source

Projection

Water Quality

USACE & EPA

GCS_North_American_1983

Navajo Nation Boundary

US Census Bureau

GCS_North_American_1983

Mines, streams, wells & STATSGO

SADSP

GCS_North_American_1983

10m DEMs

ARIA

GCS_North_American_1983

1997 Orthoimage

Terra Server

GCS_North_American_1983

 

References

Arizona Regional Image Archives.  Website: http://aria.arizona.edu/search/search.aria?path=-110&row=36&sensor=DEM

 

The Map and Geographic Information Center (1997).  Aerial Photography of Cove, Arizona.  Centennial Science & Engineering Library, University of New Mexico, Albuquerque, NM 87131-0001

 

Richardson, Kerry. (1991). Report on the 4th Indigenous Uranium Forum. Southwest Indigenous Uranium Forum.  Website: http://www.sonic.net/~kerry/cove.html

 

 

Shuey and Brown. (2004). Joint Statement before the National Research Council Committee to Assess the Scientific Information for the Radiation Exposure Screening and Education Program. Navajo Education Center, Window Rock, AZ.

 

 

Southern Arizona Data Service Program. (2004). GIS data: Bureau of Mine Minerals, Vegetation, Streams, etc .  Website: http://sdfsnet.srnr.arizona.edu/index.php?page=datamenu&lib=1&sublib=14

 

 

U.S. Environmental Protection Agency, Army Corp of Engineer & Navajo Abandoned Mine Lands Reclamation Program. (2004). Abandoned Mine Lands and Navajo Nation: Red Valley Chapter Screening Assessing Report, Apache County, Arizona and San Juan County, New Mexico. USACE Los Angeles, Los Angeles, CA.

 

U.S. Environmental Protection Agency & Army Corps of Engineers. (2000). Project Atlas: Abandoned Uranium Mines Project AZ, NM, UT – Navajolands 1994-2000. U.S Army Corps of Engineers, Los Angeles, Los Angeles, CA.

 

U.S. Environmental Protection Agency & Army Corps of Engineers & Geiger Group (2000).  The Navajo Nation Water Quality Monitoring Program.  Northwestern University.  Website: http://www.chem.northwestern.edu/~geigerf/nav/index.html

 

Yazzie, M. (April 2006). NAMLRP Interview.

 

 

 

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