Proposed Determination of the

U.S. Environmental Protection Agency Region 10

Pursuant to Section 404(c) of the Clean Water Act

Pebble Deposit Area, Southwest Alaska

July 2014

Region 10, Seattle, WA

www.epa.gov/bristolbay
July 2014

PROPOSED DETERMINATION OF THE 

U.S. ENVIRONMENTAL PROTECTION AGENCY REGION 10

PURSUANT TO SECTION 404(C) OF THE CLEAN WATER ACT

PEBBLE DEPOSIT AREA, SOUTHWEST ALASKA

U.S. Environmental Protection Agency

Region 10

Seattle, WA
Cover Photo Credits:

Main photo: Upper Talarik Creek (Joe Ebersole, EPA)

Thumbnail 1: Fishing boats at Naknek, Alaska (EPA)

Thumbnail 2: Sockeye salmon in the Wood River (Thomas Quinn, University of Washington)

Thumbnail 3: Salmon drying at Koliganek (Alan Boraas, Kenai Peninsula College)

Thumbnail 4: Age-0 coho salmon in the Chignik watershed (Jonny Armstrong)

Preferred citation: EPA (U.S. Environmental Protection Agency). 2014. Proposed Determination of the 

U.S. Environmental Protection Agency Region 10 Pursuant to Section 404(c) of the Clean Water Act, 

Pebble Deposit Area, Southwest Alaska. Region 10, Seattle, WA. 
Proposed Determination ES-1 July 2014

EXECUTIVE SUMMARY

The U.S. Environmental Protection Agency (EPA) Region 10 is requesting public comment on a proposed 

determination to restrict the use of certain waters in the Bristol Bay watershed for disposal of dredged 

or fill material associated with mining the Pebble deposit, a large ore body in southwest Alaska. EPA 

Region 10 is taking this step because of the high ecological and economic value of the Bristol Bay 

watershed and the assessed unacceptable environmental effects that would result from such mining. 

This proposed determination relies on clear EPA authorities under the Clean Water Act (CWA), and is 

based on peer-reviewed scientific and technical information. Its scope is geographically narrow and it 

does not affect other deposits or mine claim holders outside of those affiliated with the Pebble deposit. 

EPA Region 10 is taking this step pursuant to Section 404(c) of the CWA and its implementing 

regulations at 40 Code of Federal Regulations (CFR) Part 231.

Alaska’s Bristol Bay watershed (Figure ES-1) is an area of unparalleled ecological value, boasting salmon

diversity and productivity unrivaled anywhere in North America. As a result, the region is a globally 

significant resource with outstanding value. The Bristol Bay watershed provides intact, connected 

habitats—from headwaters to ocean—that support abundant, genetically diverse wild Pacific salmon 

populations. These salmon populations, in turn, maintain the productivity of the entire ecosystem, 

including numerous other fish and wildlife species.

The Bristol Bay watershed’s streams, wetlands, and other aquatic resources support world-class, 

economically important commercial and sport fisheries for salmon and other fishes, as well as a more 

than 4,000-year-old subsistence-based way of life for Alaska Natives. Each year Bristol Bay supports the 

world’s largest runs of sockeye salmon, producing approximately half of the world’s sockeye salmon. 

These sockeye salmon represent the most abundant and diverse populations of this species remaining in 

the United States. Bristol Bay’s Chinook salmon runs are frequently at or near the world’s largest, and 

the region also supports significant coho, chum, and pink salmon populations. Because no hatchery fish 

are raised or released in the watershed, Bristol Bay’s salmon populations are entirely wild. Bristol Bay is 

remarkable as one of the last places on Earth with such bountiful and sustainable harvests of wild 

salmon. One of the main factors leading to the success of this fishery is the fact that its aquatic habitats 

are untouched and pristine, unlike the waters that support many other fisheries.

Nearly 70% of the sockeye and large numbers of the coho, Chinook, pink, and chum salmon are 

harvested in commercial, subsistence, and recreational fisheries before they can return to their natal 

lakes and streams to spawn. Thus, these salmon resources have significant economic, nutritional, 

cultural, and recreational value, both within and beyond the Bristol Bay region. The Bristol Bay 

watershed’s ecological resources generated nearly $480 million in direct economic expenditures and 

sales and provided employment for over 14,000 full- and part-time workers in 2009. The Bristol Bay 

commercial salmon fishery generates the largest component of this economic activity, with an estimated 
Executive Summary

Proposed Determination ES-2 July 2014

value of $300 million (sales from fishers to processors) and employment for over 11,000 full- and parttime workers (EPA 2014: Chapter 5).

In February 2011, Northern Dynasty Minerals Ltd. (NDM) formally submitted information to the U.S. 

Securities and Exchange Commission (SEC) that put forth plans for the development of a large-scale 

mine at the headwaters of this pristine ecosystem (Figure ES-2). Their proposal outlines several stages 

of mine development, the smallest being a 2.0-billion-ton mine1 and the largest being a 6.5-billion-ton 

mine2 (Ghaffari et al. 2011, SEC 2011), both of which are larger than 90% of the known ore deposits of 

this type in the world (EPA 2014: Chapter 4).

The Pebble deposit is a large, low-grade, porphyry copper deposit (containing copper-, gold-, and 

molybdenum-bearing minerals) that underlies portions of the South Fork Koktuli River (SFK), North 

Fork Koktuli River (NFK), and Upper Talarik Creek (UTC) watersheds. Based on information provided by 

NDM to the SEC (Ghaffari et al. 2011, SEC 2011), mining the Pebble deposit is likely to involve 

excavation of the largest open pit ever constructed in North America, covering up to 6.9 square miles

(17.8 km2) and reaching a depth of as much as 0.77 mile (1.24 km) (EPA 2014: Chapter 6); for reference, 

the maximum depth of the Grand Canyon is approximately 1 mile. Disposal of resulting waste material 

would require construction of up to three mine tailings impoundments covering an additional 18.8 

square miles (48.6 km2) and waste rock piles covering up to 8.7 square miles (22.6 km2) (EPA 2014: 

Chapter 6) in an area that contains highly productive streams and wetlands. The volume of mine tailings 

and waste rock produced from the smallest mine proposed by NDM to the SEC (Ghaffari et al. 2011, SEC 

2011) would be enough to fill a professional football stadium more than 880 times, whereas the largest 

mine would do so more than 3,900 times.

In total, these three mine components (mine pit, tailings impoundments, and waste rock piles) would 

cover an area larger than Manhattan. Mine construction and operation would also require the 

construction of support facilities, including a major transportation corridor, pipelines, a powergenerating station, wastewater treatment plants, housing and support services for workers, 

administrative offices, and other infrastructure. Such facilities would greatly expand the “footprint” of 

the mine and affect additional aquatic resources beyond the scope of this proposed determination. 

Although NDM’s preliminary plans (Ghaffari et al. 2011, SEC 2011) could change, any mining of this 

deposit would, by necessity, require similar mine components, support facilities, and operational 

features.

Given the extent of streams, wetlands, lakes, and ponds both overlying the Pebble deposit and within 

adjacent watersheds, excavation of a massive mine pit and construction of large tailings impoundments 

and waste rock piles would result in discharge of dredged or fill material into these waters. This 

discharge would result in complete loss of fish habitat due to elimination, dewatering, and

 

1 Ghaffari et al. (2011) call the 2.0 stage mine the “Investment Decision Case,” which describes an initial 25-year 

open pit mine life upon which a decision to initiate permitting, construction, and operations may be based.

2 Ghaffari et al. (2011) call the 6.5 stage mine the “Resource Case,” which is based on 78 years of open pit 

production and seeks to assess the long-term value of the project in current dollars.
Executive Summary

Proposed Determination ES-3 July 2014

fragmentation	of	streams,	wetlands,	and	other	aquatic	resources.	In	addition,	water	withdrawal	and	

capture,	storage,	treatment,	and	release	of	wastewater	associated	with	the	mine	would	significantly	

impair	the	fish	habitat	functions	of	other	streams,	wetlands,	and	aquatic	resources.	All	of	these	losses	

would	be	irreversible.	

Based	upon	information	known	to	EPA	about	the	proposed	mine	at	the	Pebble	deposit	and	its	potential	

impacts	on	fishery	resources,	and	as	a	result	of	multiple	inquiries,	concerns,	and	petitions	to	EPA	to	use	

its	authorities	to	protect	these	fishery	resources,	EPA	decided	to	conduct	an	ecological	risk	assessment	

before	considering	any	additional	steps.	After	three	years	of	study,	two	rounds	of	public	comment,	and	

independent,	external	peer	review,	EPA	released	its	Assessment of Potential Mining Impacts on Salmon

Ecosystems of Bristol Bay, Alaska3	(Bristol	Bay	Assessment)	(EPA	2014)	in	January	2014.	The	Bristol	Bay	

Assessment	established	that	the	extraction,	storage,	treatment,	and	transportation	activities	associated	

with	building,	operating,	and	maintaining	one	of	the	largest	mines	ever	built	would	pose	significant	risks	

to	the	unparalleled	ecosystem	that	produces	one	of	the	greatest	wild	salmon	fisheries	left	in	the	world.	

In	simple	terms,	the	infrastructure	necessary	to	mine	the	Pebble	deposit	jeopardizes	the	long‐term	

health	and	sustainability	of	the	Bristol	Bay	ecosystem.	

The	Bristol	Bay	Assessment	characterizes	the	significant	ecological	resources	of	the	region	and	

describes	potential	impacts	on	salmon	and	other	fish	from	large‐scale	porphyry	copper	mining	at	the	

Pebble	deposit.	The	Bristol	Bay	Assessment	evaluated	these	impacts	using	three	mine	scenarios	that	

represent	different	stages	of	mining	at	the	Pebble	deposit,	based	on	the	amount	of	ore	processed.	

 Pebble	0.25	stage	mine	(approximately	0.25	billion	tons	of	ore	over	20	years)	

 Pebble	2.0	stage	mine	(approximately	2.0	billion	tons	of	ore	over	25	years)	

 Pebble	6.5	stage	mine	(approximately	6.5	billion	tons	of	ore	over	78	years)	

Ghaffari	et	al.	(2011)	indicate	that	the	total	mineral	resources	at	the	Pebble	deposit	are	now	believed	to	

be	approximately	12	billion	tons	of	ore.	Thus,	it	is	expected	that	development	of	a	mine	at	the	Pebble	

deposit	would	ultimately	be	much	larger	than	the	0.25	stage	mine	and	could	exceed	the	6.5	stage	mine.	

NDM	has	stated	to	the	public	that	“the	Pebble	deposit	supports	open	pit	mining	utilizing	conventional	

drill,	blast	and	truck‐haul	methods,	with	an	initial	mine	life	of	25	years	and	potential	for	mine	extensions	

to	78	years	and	beyond”	(NDM	2011).	This	statement,	along	with	others	to	investors,	indicates	that	NDM	

is	actively	considering	a	mine	size	between	2.0	and	6.5	billion	tons.	

Nevertheless,	EPA	also	assessed	the	impacts	of	a	much	smaller	mine	footprint	in	the	Bristol	Bay	

Assessment.	The	0.25	stage	mine	is	based	on	the	worldwide	median	size	porphyry	copper	deposit	

(Singer	et	al.	2008).	Although	this	smaller	size	is	dwarfed	by	the	mine	sizes	that	NDM	put	forward	to	the	

SEC	(Ghaffari	et	al.	2011,	SEC	2011),	its	impacts	would	still	be	significant.	

																																																													

3	For	more	information	about	EPA’s	efforts	in	Bristol	Bay	or	copies	of	the	Bristol	Bay	Assessment,	see	

http://www.epa.gov/bristolbay.	
Executive Summary

Proposed Determination ES-4 July 2014

In total, the Bristol Bay Assessment estimates that habitat losses associated with the 0.25 stage mine 

would include nearly 24 miles (38 km) of streams, representing approximately 5 miles (8 km) of 

streams with documented anadromous fish occurrence and 19 miles (30 km) of tributaries of those 

streams (EPA 2014: Chapter 7). Total habitat losses would also include more than 1,200 acres (4.9 km2) 

of wetlands, lakes, and ponds, of which approximately 1,100 acres (4.4 km2) are contiguous with either 

streams with documented anadromous fish occurrence or tributaries of those streams. For the largest 

mine that NDM put forward to the SEC (the 6.5 stage mine), stream losses would expand to 94 miles

(151 km), representing over 22 miles (36 km) of streams with documented anadromous fish occurrence 

and 72 miles (115 km) of tributaries of those streams (EPA 2014: Chapter 7). Total habitat losses for the 

6.5 stage mine would also include more than 4,900 acres (19.8 km2) of wetlands, lakes, and ponds, of 

which approximately 4,100 acres (16.6 km2) are contiguous with either streams with documented 

anadromous fish occurrence or tributaries of those streams.

To put these numbers in perspective, stream losses for just the 0.25 stage mine would equal a length of 

more than 350 football fields and the 0.25 stage mine wetland losses would equal an area of more than 

900 football fields. Although Alaska has many streams and wetlands that support salmon, individual 

streams, stream reaches, wetlands, lakes, and ponds play a critical role in protecting the genetic 

diversity of Bristol Bay’s salmon populations. Individual waters can support local, unique populations 

(Quinn et al. 2001, Olsen et al. 2003, Ramstad et al. 2010, Quinn et al. 2012). Thus, losing these 

populations would erode the genetic diversity that is crucial to the stability of the overall Bristol Bay 

salmon fisheries (Hilborn et al. 2003, Schindler et al. 2010, EPA 2014: Appendix A).

These stream, wetland, and other aquatic resource losses also would reverberate downstream, 

depriving downstream fish habitats of nutrients, groundwater inputs, and other subsidies from lost 

upstream aquatic resources. In addition, water withdrawal, capture, storage, treatment, and release at 

even the 0.25 stage mine would result in streamflow alterations in excess of 20% in more than 9 miles 

(nearly 15 km) of streams with documented anadromous fish occurrence. These streamflow changes 

would result in major changes in ecosystem structure and function and would reduce both the extent 

and quality of fish habitat downstream of the mine to a significant degree. The impacts from the larger 

mine sizes NDM has forecasted would be significantly higher. The 2.0 and 6.5 stage mines would result 

in streamflow alterations in excess of 20% in more than 17 miles (27 km) and 33 miles (53 km), 

respectively, of streams with documented anadromous fish occurrence (EPA 2014: Chapter 7).

The CWA is a law essential for EPA’s mission, which is to protect and restore the environment and public 

health for current and future generations. Section 404(c) of the CWA authorizes EPA to prohibit, restrict, 

or deny the use of any defined area in waters of the United States for specification as a disposal site 

whenever it determines, after notice and opportunity for public hearing, that the discharge of dredged 

or fill material into the area will have an unacceptable adverse effect on fishery areas (including 

spawning and breeding areas). EPA has used its Section 404(c) authority judiciously and sparingly, 

having completed only 13 Section 404(c) actions in the 42-year history of the CWA.
Executive Summary

Proposed Determination ES-5 July 2014

As a first step in the regulatory process pursuant to Section 404(c), EPA Region 10 coordinated with 

NDM, the Pebble Limited Partnership (PLP),4 and the State of Alaska to provide them an opportunity to 

submit information that demonstrated either that no unacceptable adverse effects would result from 

discharges associated with mining the Pebble deposit or that actions could be taken to prevent 

unacceptable adverse effects on fishery areas. EPA Region 10 met with both NDM/PLP and the State of 

Alaska and extended the time period for both to submit this information. 

Both NDM/PLP and the State of Alaska submitted information that raised scientific and technical issues,

most of which had been previously raised in public comments on the Bristol Bay Assessment. However, 

this information did not demonstrate to the satisfaction of EPA Region 10 that no unacceptable adverse 

effects on fishery areas will occur should the disposal of dredged or fill material associated with mining 

the Pebble deposit proceed.

Therefore, EPA Region 10 has decided to take the next step in the Section 404(c) review process, 

publication of this proposed determination. As part of a Section 404(c) proposed determination, the EPA 

Regional Administrator must identify a defined area, known as the disposal site, where its prohibitions 

or restrictions would apply. In this case, the proposed geographic boundaries of the potential disposal 

site are the waters within the mine claims held by NDM subsidiaries, including PLP, that fall within the 

SFK, NFK, and UTC watersheds (Figure ES-3). EPA Region 10 focused on this area because it determined 

that it best represents the smallest geographical area where the discharge of dredged or fill material 

associated with mining the Pebble deposit is most likely to occur.

To protect important fishery areas in the SFK, NFK, and UTC watersheds from unacceptable adverse 

effects, EPA Region 10 recognizes that losses of streams, wetlands, lakes, and ponds and alterations of 

streamflow each provide a basis to issue this Section 404(c) proposed determination.

Given the proposals made by NDM to develop 2.0- and 6.5-billion-ton mines at the Pebble deposit 

(Ghaffari et al. 2011, SEC 2011) and EPA’s evaluation of the 0.25-billion-ton mine (EPA 2014), the 

Regional Administrator has reason to believe that mining of the Pebble deposit at any of these sizes, 

even the smallest, could result in significant and unacceptable adverse effects on ecologically important 

streams, wetlands, lakes, and ponds and the fishery areas they support.

Accordingly, the Regional Administrator proposes that EPA restrict the discharge of dredged or fill 

material related to mining the Pebble deposit into waters of the United States within the potential 

disposal site that would, individually or collectively, result in any of the following.

 

4 PLP was created in 2007 by co-owners NDM and Anglo American PLC to design, permit, construct, and operate a 

long-life mine at the Pebble deposit (Ghaffari et al. 2011). Anglo American PLC withdrew from the partnership in 

late 2013; since 2013, NDM has been the sole partner in PLP.
Executive Summary

Proposed Determination ES-6 July 2014

1. Loss of streams

a. The loss of 5 or more linear miles of streams with documented anadromous fish5 occurrence; or

b. The loss of 19 or more linear miles of streams where anadromous fish are not currently 

documented, but that are tributaries of streams with documented anadromous fish occurrence; 

or

2. Loss of wetlands, lakes, and ponds. The loss of 1,100 or more acres of wetlands, lakes, and ponds 

contiguous with either streams with documented anadromous fish occurrence or tributaries of 

those streams; or

3. Streamflow alterations. Streamflow alterations greater than 20% of daily flow in 9 or more linear 

miles of streams with documented anadromous fish occurrence.

These restrictions derive from the estimated impacts resulting from the discharge of dredged or fill 

material associated with construction and routine operation of a 0.25 stage mine at the Pebble deposit, 

as evaluated in the Bristol Bay Assessment (EPA 2014).

EPA Region 10’s evaluation of relevant portions of the Section 404(b)(1) Guidelines (40 CFR Part 230) 

further demonstrates that discharge of dredged or fill material resulting in the level of adverse effects 

identified in the proposed restrictions could result in unacceptable adverse effects on fishery areas.

Degradation of these aquatic resources would be even more pronounced given extensive cumulative 

impacts at successive stages of mine expansion (i.e., 2.0 and 6.5 stage mines or larger) at the Pebble 

deposit, including elevated instream copper concentrations sufficient to cause direct toxicity to fish. 

Toxic effects on fish would include fish kills; reduced survival, growth, and/or reproduction; and 

reduced sensory acuity, which is important to salmon for locating natal streams, finding food, and 

avoiding predators.

EPA Region 10 recognizes it has underestimated potential adverse effects on resources within the SFK, 

NFK, and UTC watersheds from mining the Pebble deposit for several reasons. This evaluation does not 

include footprint impacts associated with all of the components necessary to construct and operate such 

a mine (e.g., a major transportation corridor, pipelines, a power-generating station, wastewater 

treatment plants, housing and support services for workers, administrative offices, and other 

infrastructure). It also does not rely upon impacts resulting from potential accidents and failures as a 

basis for its findings. There is a high likelihood that wastewater treatment plant failures would occur,

given the long management horizon expected for the mine (i.e., decades). There is also real uncertainty 

as to whether severe accidents or failures, such as a complete wastewater treatment plant failure or a 

tailings dam failure, could be adequately prevented over a management horizon of centuries, or even in 

perpetuity, particularly in such a geographically remote area subject to climate extremes. If such events 

 

5 Anadromous fish are those that hatch in freshwater habitats, migrate to sea for a period of relatively rapid 

growth, and then return to freshwater habitats to spawn. For the purposes of these restrictions, anadromous fish 

refers to coho or silver salmon (Oncorhynchus kisutch), Chinook or king salmon (O. tshawytscha), sockeye or red 

salmon (O. nerka), chum or dog salmon (O. keta), and pink or humpback salmon (O. gorbuscha).
Executive Summary

Proposed Determination ES-7 July 2014

were to occur, they would have profound ecological ramifications. By not relying on potential accidents 

and failures, EPA Region 10 has employed a conservative analysis of adverse effects.

Known compensatory mitigation techniques are unlikely to offset impacts of the nature and magnitude

described in the proposed restrictions. Compensatory mitigation is the concept of improving stream or 

wetland health in other parts of the watershed to compensate for stream or wetland destruction or 

degradation in a separate area. Compensatory mitigation efforts typically involve restoration and 

enhancement of waters that have potential for improvement in ecological services. However, the waters 

of the Bristol Bay watershed are already among the most productive in the world. EPA Region 10 sees 

little likelihood that human activity could improve upon the high-quality natural environment in the 

Bristol Bay watershed that nature has created and that has thus far been preserved. Compensation 

methods proposed by PLP, including placement of instream structures, stream fertilization, and 

construction of spawning channels, have typically had only variable, local, or temporary effects, were 

designed for use in degraded watersheds, or resulted in adverse, unintended consequences (EPA 2014: 

Appendix J).

Mine alternatives with lower environmental impacts at the Pebble deposit are not evaluated in either 

the Bristol Bay Assessment or this Section 404(c) proposed determination. If these proposed 

restrictions are finalized, proposals to mine the Pebble deposit that have impacts below each of these 

restrictions would proceed to the Section 404 permitting process with the U.S. Army Corps of Engineers. 

Any such proposals would have to meet the statutory and regulatory requirements for permitting under 

Section 404. 

After evaluating available information, EPA Region 10 has reason to believe that unacceptable adverse 

effects on fishery areas (including spawning and breeding areas) could result from the discharge of 

dredge or fill material associated with mining the Pebble deposit. Further, it has not been demonstrated 

to the satisfaction of EPA Region 10 that no unacceptable adverse effect(s) will occur.

EPA Region 10 is soliciting public comment on all issues discussed in this proposed determination, 

including likely adverse impacts on fishery resources, mitigation measures to potentially address these 

impacts, and other options to restrict or prohibit potentially harmful discharges of dredged or fill 

material associated with mining the Pebble deposit. All comments will be fully considered as EPA Region 

10 decides whether to withdraw the proposed determination or forward to EPA Headquarters a 

recommended determination to restrict the use of certain waters in the SFK, NFK, and UTC watersheds 

in southwest Alaska as disposal sites for the discharge of dredged or fill material associated with mining 

the Pebble deposit. Should EPA Region 10 make a recommended determination, EPA Headquarters will 

then determine, based on the recommended determination, public comments received on the proposed 

determination, and all other available, relevant information, whether to issue a final determination 

under Section 404(c).
Executive Summary

Proposed Determination ES-8 July 2014

Figure ES-1. The Bristol Bay watershed, composed of the Togiak, Nushagak, Kvichak, Naknek, Egegik, and Ugashik River watersheds and 

the North Alaska Peninsula. Only selected towns and villages are shown on this map.
Executive Summary

Proposed Determination ES-9 July 2014

Figure ES-2. The Nushagak and Kvichak River watersheds.
Executive Summary

Proposed Determination ES-10 July 2014

Figure ES-3. The potential disposal site delineated in the proposed determination. 
Executive Summary

Proposed Determination ES-11 July 2014

References

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Ecosystems of Bristol Bay, Alaska. Final Report. EPA 910-R-14-001A-C. Washington, DC. 

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Preliminary Assessment of the Pebble Project, Southwest Alaska. Document 1056140100-REP-R0001-

00. February 15. Prepared for NDML by WARDROP (a Tetra Tech Company), Vancouver, BC.

Hilborn, R., T. Quinn, D. Schindler, and D. Rogers. 2003. Biocomplexity and fisheries sustainability. 

Proceedings of the National Academy of Sciences of the United States of America 100:6564–6568.

NDM (Northern Dynasty Minerals Ltd.). 2011. News Releases—February 23, 2011, Northern Dynasty 

Receives Positive Preliminary Assessment Technical Report for Globally Significant Pebble Copper-GoldMolybdenum Project in Southwest Alaska. Available: 

http://www.northerndynastyminerals.com/ndm/NewsReleases.asp?ReportID=595724. Accessed: 

June 27, 1014.

Olsen, J. B., S. J. Miller, W. J. Spearman, and J. K. Wenburg. 2003. Patterns of intra-and inter-population 

genetic diversity in Alaskan coho salmon: implications for conservation. Conservation Genetics

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bears. Evolutionary Ecology Research 3(8):917−937.

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asynchrony at fine spatial scales: a case history of sockeye salmon (Oncorhynchus nerka) population 

structure in Alaska, USA. Canadian Journal of Fisheries and Aquatic Science 69:297–306. 

Ramstad, K. M., C. A. Woody, and F. W. Allendorf. 2010. Recent local adaptation of sockeye salmon to 

glacial spawning habitats. Evolutionary Ecology 24(2):391–411.

Schindler, D. E., R. Hilborn, B. Chasco, C. P. Boatright, T. P. Quinn, L. A. Rogers, and M. S. Webster. 2010. 

Population diversity and the portfolio effect in an exploited species. Nature 465:609–612.

SEC (Securities and Exchange Commission). 2011. Northern Dynasty Minerals Ltd. February 24, 2011 

Filing. Available: 

http://www.sec.gov/Archives/edgar/data/1164771/000106299311000722/0001062993-11-

000722-index.htm. Accessed: June 20, 2014.

Singer, D. A., V. I. Berger, and B. C. Moring. 2008. Porphyry Copper Deposits of the World: Database and 

Grade and Tonnage Models. Open-File Report 2008-1155. USGS, Menlo Park, CA.