Supplemental Draft Environmental Impact Statement

March 2014 •

Report on wetland components of the EIS Paul H. Glaser, Ph.D.

General Comments 1. Distinguishing ombrotophic bogs from minerotrophic fens

A large proportion of the wetlands within the NorthMet site were classified as coniferous bogs, which the report states may include both ombrotophic (raised) bogs and minerotrophic fens. However, the EIS later states that peatlands were divided into ombrotophic (i.e. solely rain nourished) and minerotrophic (nourished by both precipitation and water that has percolated through mineral soil) classes using the criteria defined by Eggers (2011). Unfortunately, these criteria are not consistent with the scientific literature, which has developed a rigorous set of standards for distinguishing ombrotophic bogs from minerotrophic fens (see my specific comments on the Eggers memorandum).

Both the NorthMet EIS and Eggers (2011) memorandum assume that ombrotophic bogs can be distinguished by a nearly continuous cover of Sphagnum, the dominance of so-called bog indicator species (e.g. black spruce (Picea mariana) and ericaceous shrubs), and acidic surface waters. However, both the scientific literature stresses that no plant species are solely confined to raised bogs and therefore there are no bona fide "bog" indicator species. Ombrotophic bogs can only be distinguished by the absence of fen-indicator species, which are faithful indicators of minerogenic surface waters. The appearance of fen indicator species (e.g. northern white cedar Thuja occidentalis), bog birch ((Betula pumila var. glandulifera), balsam fir (Abies balasamea), alder (Alnus sp.), and willow (Salix) in the coniferous bog type at the NorthMet site clearly indicates that these peatlands are minerotrophic fens and not ombrotrophic bogs. This interpretation is further supported by the pH values recorded for surface water in coniferous bogs at the NorthMet site that all typical of a rich to extremely rich fen (see comments below).

This distinction between ombrotophic and minerotrophic peatlands is important since this ombrotrophy was used to evaluate the vulnerability of the NorthMet wetlands to mining activities. The key criteria for distinguishing ombrotrophic bogs from minerotrophic fens has been described in detail by Glaser et al (1981, 1990,1997; 2004ab), Glaser (1987, 1992ab,1997) and also Sjörs (1948, 1964) among many others. These criteria are::

a) landform type (3D morphology of a peat deposit): The interior of a raised bog is always higher than the peatland margins, whereas fens have flat or concave cross-sectional profiles,

b) the absence of fen indicator species These are species that cannot tolerate surface waters in which the pH is 4.2 or lower and Ca concentrations are 2 mg/l or lower. In northern Minnesota, northern white cedar Thuja occidentalis), alder (Alnus spp.), balsam fir Abies balsamea, bog birch (Betula pumila var. glandulifera), willows (Salix spp.), and Juncus stygius etc are common fen indicator species that never grow in an ombrotrophic bog. It should be kept in mind that there are no bog indicator species since all the species on bogs also

grow in fens and in fact many of the dominant species on omrotophic bogs (e.g. Picea mariana, Sphagnum spp. Ledum groenlandicum, Chamaedaphne calyculata etc can also be dominants on fens)

c) surface water chemistry (bogs consistently have surface waters with a pH <4.2 and Ca concentrations >2 mg/l, whereas fens have higher values).

d) hydrology (ombrotrophic bogs receive all their water and salts solely from the atmosphere, whereas minerotrophic fens also receive inputs of waters that have percolated through mineral soil).

These distinguishing characteristics have been documented for peatlands across northern Minnesota (Glaser et al. 1981, 1983,1990, 1997; Glaser 1987,1992a) and elsewhere across the circumboreal region of the northern hemisphere (Sjörs 1948, 1964: Glaser and Janssens 1986: Glaser 1992b, Glaser et al 2004ab; 2006). In addition, the linkage of this classification to groundwater hydrology (which provides direct confirmation of the ombrotophic/minerotrophic concept) was also documented for peatlands in Minnesota (e.g. Siegel and Glaser 1987; Siegel et al. 1995, 2006; Glaser et al. 1990, 1997) and elsewhere (e.g. Glaser et al. 2004). These criteria were adopted by the Minnesota Department of Natural Resources (2003: pp 215-221) description of native plant communities in northeastern Minnesota.

The "coniferous bog class" at the NorthMet site seems to be best described as a minerotrophic fen forest. It should be kept in mind that poor fens can also have a high cover of Sphagnum moss and appear similar to raised bogs but are distinguished by the appearance of a few fen indicator species and also their surface water chemistry, which has a pH of 4.3 or higher and Ca concentrations above 2 mg/l. In fact some of these coniferous bog sites seem to be extremely-rich fens based on the occurrence of extremely-rich fen indicators (e.g. Thuja occidentalis) and surface waters with a pH above 6.8. These particular sites seem to be similar to the spring-fen forests described for the Glacial Lake Agassiz peatlands in northern Minnesota (Glaser et al. 1990; Glaser 1987,1992b; see also MN-DNR 2003) and the Hudson Bay Lowland (Glaser et al. 2004a). Hydrogeological investigations have shown that these spring-fen forests are localized discharge zones for groundwater (Siegel and Glaser 1987, Glaser et al 2004a; 2006). In addition, these criteria have been directly linked to the hydrology of peatlands in northern Minnesota and elsewhere providing a confirmation of the ombtrophic/minerotrophic classification system (e.g. Siegel and Glaser 1987; Siegel et al. 1995; Glaser et al. 1990, 1997) and elsewhere (e.g. Glaser et al. 2004a).. The datasets that supports the NorthMet wetland classification does not allow an explicit critique of whether the wetlands within this site are ombrotophic bogs or minerotrophic fens. These data should have been reported for well defined vegetation plots so it would be possible to discern actual plant assemblages, the relative abundance of all species, and the linkage of species assemblages to surface water chemistry. The surface water chemistry from each vegetation plot should have been analyzed with a pH meter and major cations particularly Ca.

2. Hydraulic connectivity of ombrotrophic bogs to groundwater flow systems and potential sensitivity to dewatering operations at mine pit.

Even if ombrotophic raised bogs are present within the study area they may still be hydraulically connected to groundwater flow systems and sensitive to impacts from mine development unless they support perched water-table mounds (i.e. perched recharge mounds). Perched recharge mounds tend to develop over a localized confining stratum (e.g. clay layer) within an otherwise more porous deposit of sand and gravel, silty sand, or sandy silt (Todd & Mays 2004). Perched recharge mounds are likely to occur within wetlands of the NorthMet site but no convincing evidence is provided to support their presence. A convincing test would be water level measurements in piezometer nests installed above and below the hydraulic confining layers that demonstrate the existence of a perched water table mound. It should be kept in mind that water levels will quickly respond to precipitation events in any piezometer installed within an unconfined aquifer. It should also be kept in mind that, the magnitude of the pumping tests performed for the EIS is probably orders of magnitude lower than that of actual mine dewatering operations. 3) Sensitivity of wetlands to contaminant plumes propagating from rock waste or tailings deposits.

Wetlands in recharge zones (areas where surface waters move downward and recharge the underlying groundwater system) would be much less vulnerable to contaminant plumes transported through groundwater flow systems. However, all wetlands within the study area could still be vulnerable to contamination transported by runoff during the flush of spring runoff. This source of contamination would be greatest after winters with a deep winter snowpack and an abrupt spring thaw. 4) Mitigation Plans

Once again I am not happy with the mitigation plans. The NorthMet team seems to be committed to their previous plans to restore wetlands at the Zimm, Hinckley, and Aitken County sites. As I described before I think we are missing a golden opportunity to preserve and restore one of the most outstanding peatland complexes in northwestern Minnesota. This wetland complex is found in the Saint Louis River watershed and has been previously disturbed by drainage ditches, roadways, and a railroad crossing. However, it contains excellent examples of raised bogs, the most outstanding patterned fen in northeastern Minnesota, and populations of several rare, endangered or threatened plant species including Carex exilis, Rhynchospora fusca, Xyris montana, and Juncus stygius. Moreover, the site is presently tax-forfeit land and can be purchased, restored, and donated to the Minnesota DNR to be operated as a Scientific and Natural Area. The peatlands within this tract are more comparable to those of the NorthMet site with the principal exception of their larger size.

5. Monitoring Plan

This EIS recognizes the importance of monitoring wetlands for future impacts from mining operations given that: "Groundwater modeling cannot reasonably estimate potential indirect wetland effects; therefore, analog impact zones can provide a reasonable estimate of the extent of potential indirect wetland effects resulting from hydrologic effects. In addition, the evaluation of theoretical groundwater drawdown levels can help estimate what types of potential indirect wetland effects might occur. However, wetland hydrology is a complex mix of precipitation, surface runoff, and in some cases, groundwater. The response of complex natural systems to human disturbances can only be estimated. Therefore, monitoring of wetland hydrology and vegetation communities would occur to document the extent and magnitude of wetland responses (potential indirect effects) to human disturbances. The monitoring plan, developed as part of the Section 404 permit, would be based on those wetlands that have a high likelihood of indirect effects as a result of groundwater drawdown. Permit conditions would likely include an adaptive management plan to account for any additional effects that may be identified in the annual monitoring and reporting." The wetlands within the NorthMet site should be monitored by repeat sampling of permanent plots that are laid out prior to the onset of mine development. I would suggest using standardized relevé plots (100 m2 for nonforested sites and 400 m2 for forested sites) following the procedures described by Glaser et al. (1981; 1990) and adopted by the County Biological Survey of the Minnesota Department of Natural Resources. The vegetation within these plots needs to be documented prior to the onset of mine development in order to provide baseline data for evaluating any future changes that may be produced by mining operations. All species within the plot need to be identified (not just the dominant species) and assigned a semi-quantitative or quantitative measure of abundance and dispersion. In each plot water samples should be collected from the peat surface (if there is standing water) or shallow pits. These samples should be analyzed according to standardized procedures. It is strongly recommended that pH measurements should be made at the time of sampling or the end of each sampling day with a pH meter that has been calibrated with appropriate pH buffers. The water samples should then be filtered and acidified for analysis of cations (but not anions). In addition to the metals and anions most likely to be contaminants from mining operations these measurements also need to include Ca. I think the EIS statement would have been a much stronger document with respect to the wetland section if the vegetation data was also presented for relevé plots or randomized grid of sample points (I think the relevé approach is much more practical and would then be directly comparable to MN DNR database on native plant communities. I would also highly recommend some data on peat depths (which can be quickly compiled with a probe). The periodic re-sampling of these plots would provide the best and most cost-efficient

indicator for major impacts of mining operations on the wetlands in the NorthMet site. 6. Specific Comments (original text in black italics; my comments in red) 4.2.3.1.2 Hydrology, Wetland Vegetation, and Community Types Because of the general lack of interaction between the surficial and bedrock aquifers, the hydrology of many wetlands at the Mine Site is primarily supported by direct precipitation with some variable surficial groundwater components from the uplands. Organic and mineral soils at the Mine Site are typically perched over the dense till or a local sandy textured surficial aquifer, resulting in perched wetlands. [Please explain how a perched recharge mound could develop over a sandy textured aquifer. This statement does not seem reasonable according to the description of perched recharge mounds in Todd & Mays (2004] The primary method for water to move across the landscape towards the Partridge River is either by lateral flow that is either on the surface or within the subsurface soil. Surface flow laterally across the wetland complexes is negligible because of the flat slopes and surface roughness [What about during the flush of spring snowmelt when the winter snow pack melts? The meltwaters must drain downslope]. The wetlands on the site receive minimal surficial runoff from the upland areas because the soil texture allows rapid infiltration (Barr 2008h) [What about during the flush of spring snowmelt when the ground is still partially frozen?]. The bedrock has low primary permeability, so groundwater flow within the bedrock is through fractures or other secondary porosity features. Because of the low permeability of the bedrock, the interaction between the surficial deposits and the bedrock aquifers is assumed to be insignificant, according to Siegel and Ericson (1980) (Barr 2010d). Lateral flow within the soils is typically very slow. Fibric peat at the surface allows infiltration of surficial water; however, the more highly decomposed sapric peat has greatly reduced lateral and vertical hydraulic conductivity compared to the fibric peat. Therefore, water tends to stay perched and stored within the large peat complexes, which typically exhibit only subtle variations in the water tables over time [Have any perched water tables been documented by hydraulic head measurements from nests of piezometers?]. The silty sand or clay that typically underlies the organic soil has low hydraulic conductivity and, therefore, is a contributing factor that helps maintain the hydrology of the wetlands. The silty sands are sands mixed with clay and silt that are not permeable enough to be used as drainage sands [But there could still be significant infiltration and solute transport over time through both the peat strata and the silty sand. There is a difference between slow rates of flow and no flow. Please see papers on peatland hydrology from the Glacial Lake Agassiz peatlands and elsewhere (e.g. Siegel and Glaser 1987; Siegel et al. 1995; Reeve et al. 2000, 2001: Glaser et al 1997; Levy et al in press).

The soils and hydrology at the Mine Site support stable wetland systems comprised in large part by open and coniferous bogs, as well as shrub carr/alder thickets dominated by alder and willows pecies, and forested wetland communities comprised of hardwood swamps and coniferous swamps. Most of the wetland vegetation present at the Mine Site (69 percent) is indicative of acid peatland systems (i.e., open and coniferous bogs) that are dependent on precipitation rather than groundwater for hydrologic inputs and reflect a perched water table. Potential effects are discussed in Section 5.2.3. [What was the pH and Ca concentrations of the surface waters in these peatlands? A raised bog, which is ombrotophic (solely nourished by rain) has a pH less than 4.2 and Ca concentrations less than 2 mg/l. In Minnesota raised bogs have surface waters with a very narrow range in pH (3.6-4.2), whereas the pH range for fens (4.3-7.3) barely extends into the basic range of the pH scale. Even rain water is typically acidic in Minnesota with a pH of about 5.0-5.6 (MPCA). Given the small size of the peatlands in the NorthMet site and the absence of any evidence that these peat deposits are mounded (with interior elevations higher than their margins) it appears that these peatlands are mostly poor fens (pH range of 4.3-4.8 and Ca concentrations of 3-8 mg/l) or even rich fens (pH 5.2-6.7). Pre-NorthMet Project Proposed Action wetland hydrology monitoring reports, to meet reporting requirements, have been compiled and document 5 years of pre-project planning and monitoring at the Mine Site (2005 to 2009). PolyMet has continued to conduct wetland hydrology monitoring at the Mine Site since 2009. Future wetland hydrology monitoring reports would be submitted in accordance with any permit issued. The degree of hydraulic connection between the wetland areas and adjacent unconsolidated deposits and bedrock at the Mine Site is expected to be variable, depending on the characteristics of the wetlands and the localized hydraulic conductivity and degree of bedrock fracturing. The hydraulic conductivity of the bedrock and surficial deposits have been estimated at the Mine Site by a variety of methods, including conducting aquifer tests and using grain-size distribution data from soil borings and ranges over several orders of magnitude. Data collected during a 30-day pumping test at the Mine Site showed a small amount of drawdown in the deep wetland piezometer nearest to the pumping well, but there was no detectable drawdown at other water table or deep wetland piezometers, indicating that the connection between the bedrock, unconsolidated deposits, and wetlands may be relatively weak. Virtually all water movement in peat wetlands occurs horizontally in the upper layers of peat. The deeper, more decomposed peat soils limit vertical seepage because of the low hydraulic conductivities (approximately 0.0028 ft/day) and the wetland hydrology is simply perched on the relatively impermeable peat layer.[Even though the hydraulic conductivity of the peat can be several orders of magnitude higher in the near-surface peat (acrotelm) than in deeper layers (catotelm) there could still be significant lateral or vertical flow and solute transport within the deeper peat. The assumption of "perched" conditions needs to be verified by profiles of pore-water chemistry and more detailed profiles for hydraulic head] Vertical seepage losses from wetlands without peat soils would only have the potential to occur in

isolated areas of contiguous, high hydraulic conductivity bedrock faults and fracture zones located under isolated areas of high hydraulic conductivity glacial till and aligned with wetlands containing high hydraulic conductivity soils (Barr 2010d; Barr 2011j). [What about wetlands underlain by sandy textured aquifers?] There is a surface drainage divide oriented generally from southwest to northeast near the northern border of the Mine Site. The majority of the Mine Site, approximately 80 percent, drains south to the Partridge River through extensive wetland complexes. The remaining 20 percent of the Mine Site drains north to the One Hundred Mile Swamp and the Partridge River or northeast to the Partridge River. The 2005 to 2009 wetland hydrology monitoring has determined the following (Barr 2010d): The four full years of monitoring wetland well data indicated that the large fluctuations in water levels exhibited within the majority of the wetlands are indicative of wetlands supported primarily by precipitation and local surface runoff. The hydrology of these wetlands tends to fluctuate in a pattern that closely mirrors weather patterns. The shrub swamp wetlands located near the downstream portion of the project generally show more stable water levels due to larger watershed areas and some apparent groundwater inflow. The groundwater flowpaths are generally short with recharge areas (uplands) located close to the discharge areas (wetlands). Surface water runoff and local groundwater contributions from uplands can cause increased mineral content within the water in adjacent wetlands. Wetlands that are solely dependent on precipitation for their hydrology are classified as ombrotrophic and would likely not be susceptible to effects from groundwater drawdown associated with mining operations (Eggers 2011a). Potential effects are discussed in Section 5.2.3. [I have not seen any definitive evidence presented that true "ombrotophic" raised bogs occur within the NorthMet site] There is a general lack of connectivity between the shallow water table in the wetlands and the deeper bedrock aquifer. The depth of soil and till overlying the bedrock ranges up to 33 ft, with bedrock outcrops present that alter local groundwater flowpaths. A pumping and isotope test conducted in 2006 indicated that the groundwater pumped during a 30-day pump test was derived from aquifer recharge rather than surface water seepage from surface water features such as the Northshore Mine Pit or wetlands. The variability of the bedrock and soil surface, along with the location of the surface water divide, creates localized, short, surficial groundwater flowpaths within the watersheds on the Mine Site [What isotopes were used as tracers? Tritium? I would like to see their data if it is available]. From 2005 to 2009, the maximum water level fluctuation was less than 12 inches in two wetlands (58 and 114) and between 12 and 18 inches in all other wetlands. Wells located in the southwest and south-central areas of the Mine Site show the greatest range of water table fluctuations, while wells in the northwest area of the Mine Site show the least fluctuation.The wetlands on the Mine Site

exhibit stable year-to-year water levels and elevations. Water levels in all wells fluctuated in direct response to precipitation events, with the exception of one well in 2008 and 2009 and one well in 2009. These two wells showed stability indicative of contributing discharge from the larger upstream watersheds [These results are not surprising. Water levels in piezometers installed in unconfined aquifers should respond rapidly to precipitation events regardless of whether they are located in zones of recharge, discharge or lateral flow.] The hydrographs in the monitored black spruce and tamarack dominated wetlands (coniferous bogs) exhibited a stable water table with some fluctuations indicative of saturated, precipitation-driven hydrology (i.e., rapid response to precipitation with mid summer drawdown). [Evapotranspirational losses would be limited by the xeromorphic features of the conifer trees and ericaceous shrubs] The coniferous bog communities have a tree canopy of black spruce and tamarack with occasional balsam fir, [If the peatland has balsam fir and more than the occasional tamarack it is probably not a true ombrotophic (raised) bog] while stunted forms of these species may exist in open bog communities. White cedar and deciduous swamp birch are also occasionally found in this community [Northern white cedar never grows in a true raised bog! This species is a calciphile (calcium-loving plant) and is considered an indicator of an extremely-rich fen in Minnesota; The so-called swamp birch (Betula pumila var. glandulifera?) is also a fen indicator species and never grows in the true raised bog]. Shrubs are usually ericaceous (belonging to the heath family) species such as leatherleaf, bog-Labrador tea, and cranberry. Sphagnum moss comprises an almost continuous mat with interspersed, non dominant forbs such as bunchberry and blue bead lily along with sedges and grasses [This community seems typical of a fen] Hydrologically, this complex is characterized by a relatively stable year-to-year water table (Barr 2006e; Barr 2010d). All but one of the coniferous bogs identified at the Mine Site are rated as high-quality in accordance with the MnRAM for Evaluating Wetland Functions. This wetland has some fill and therefore was rated as moderate quality. Wetlands hydrology can be driven by precipitation, or by groundwater, or a combination or both. Wetlands identified as open bogs or coniferous bogs under the Eggers and Reed (1997) classification system can be further subcategorized as either ombrotrophic (hydrology and mineral inputs entirely from direct precipitation) or somewhat minerotrophic (some degree of mineral inputs from groundwater and/or surface water runoff). This is important because ombrotrophic bogs would likely not be affected by groundwater drawdowns associated with proposed mining operations, whereas more minerotrophic bogs would have a higher likelihood of being affected (Eggers 2011a) [There seems to be confusion regarding the relationship of ombrotrophic raised bogs to groundwater flow systems. Siegel and Glaser and their co-workers have repeatedly published direct evidence that raised bogs (in addition to fens) are directly connected to groundwater flow systems in the underlying mineral sediments both in large peat basins (Siegel & Glaser 1987, Siegel et al, 1995;

Glaser et al. 1990, 1997; 2004ab, 2006) and smaller peatlands (McNamara et al 1992). These publications demonstrate that peatland development (to bog or fen) is determined by the local hydrogeologic setting rather than surface processes as suggested here (e.g. see Glaser et al 1997, 2004b, 2006). Ombrotophic raised bogs can therefore be susceptible to alterations of groundwater flow and solute transport as was demonstrated in the Lost River bog-fen complex in northern Minnesota (Glaser et al 1990 but also see Siegel et al. 1995). In addition, this report does not provide direct evidence for the occurrence of ombrotrophic raised bogs within the NorthMet site. The EIS needs to specify that some peatlands at this site have the following features: 1) are in fact mounded (i.e. raised) 2) contain no fen indicators 3) have surface waters with a pH less than 4.2 and Ca less than 2 mg/l Otherwise a discerning reader might assume that the conifer bog class represents poor fens. 4-181 Bog rush (Juncus stygius var. americanus) is listed as a species of special concern in Minnesota and as an RFSS in the Superior National Forest. Within Minnesota, bog rush is distributed across the northern and northeastern Arrowhead counties in large patterned peatlands and calcareous fens. It was first documented in St. Louis County in 1886 (Bell Museum of Natural History 2011). It is generally not a dominant species; even in ideal, large-patterned peatland settings, it occurs in isolated colonies with scattered individuals (MDNR 2011m). Bog rush is a perennial graminoid species that occurs in full sun, and, generally, it is restricted to narrow wet zones of bogs and fens where it can exploit small gaps in surrounding vegetation. Since it often grows in calcareous fens, it is influenced in some way by mineralized groundwater. It flowers and bears fruit in mid to late summer (eFlora 2011). Threats to J. stygius var. americanus include climate warming, water diversion (since it cannot compete well without vegetation gaps caused by inundation), and invasion of non-native species. Juncus stygius is a fen indicator species and never occurs on an ombrotophic bog. It is characteristic of poor-fens located around the marginal fringes of raised bogs and poor fen water tracks. (see Glaser 1992bc). It is widespread across the boreal region of North America but usually in very small and highly localized disjunct populations. The principal exception is on the Kenai Peninsula of south-central Alaska where Juncus stygius is widespread (but again growing in small localized populations). Page 4-433: Bogs in the federal lands consist of leatherleaf and bog Labrador-tea, with scattered speckled alder, swamp birch, tamarack, and, in some areas, cattail and sedges. Sphagnum moss was observed to cover 80 to 90 percent of the bogs.

Other species encountered during the field work include: black spruce, tamarack, blueberry, small fruited bog cranberry, willows, purple pitcher plant, marsh cinquefoil, cottongrass, round sundew, starflower, bunchberry, and Solomon’s sea l(AECOM 2011a). These peatlands are clearly minerotrophic fens and not ombrotrophic bogs. Alders, swamp birch, catails etc are fen indicator species and in fact alders are most abundant at peatland margins (laggs) or in non-peat wetlands. In addition: willows (Salix), marsh cinquefoil (Potentilla fruticosa?) are restricted to minerotrophic fens. Poor fens with high cover of Sphagnum are common across northern Minnesota and elsewhere. 4-450 Wetlands on Tract 1 consist primarily of early successional coniferous swamps, shrub wetlands, and open water wetlands. Hay Lake, Rice Lake, an unnamed lake, and the Pike River are the dominant water features. Large bogs dominate much of the east-central portion of Tract 1.Several wetlands were created or enlarged due to impoundment of streams by beaver dams. Raised water levels resulted in stands of dead and dying spruce along portions of the Pike River(AECOM 2011b). Bogs within Tract 1 are dominated by leatherleaf and bog Labrador-tea, with scattered young speckled alder, bog birch, tamarack, and in some areas, narrow-leaved cattail and sedges.Sphagnum and club moss often cover 80 to 90 percent of the bog. Scattered (less than 5 percent) black spruce (some dead) and immature tamarack are found in the tree layer. Lowbush blueberry, small-fruited bog cranberry, bog rosemary, and small willows are also common. Other species encountered include cottongrass, wild iris, wild raspberry, bunchberry, and northern bog orchid (AECOM 2011b). The description of the "conifer bog" class includes fen indicator species and therefore represents ether a poor or rich fen forest or a mixture of a raised bog with the poor fen plant assemblages along its margins. The fen indicator species listed are alders, bog birch, catails and other taxa (Iris and raspberry). The presence of Sphagnum, black spruce and shrubs of the Ericaceae is not indicative of a raised bog because these species have broad ecological tolerances and can be dominants in both bogs and fens. The wording of this paragraph may be misleading since the aerial photograph of this area presented in Figure 4.3.2-1 (Tract 1 Hay Lake Lands) contains a wetland in sections #17 and 20 that has the radiating forest patterns typical of a raised bog that may have been burned in part. However this polygon is classified as conifer swamp in Figure 4.3.3-3. (also see comments below) Figures 4.3.2-3 Tract 2 Lake County North Lands and Track 3 Wolf Lands 1

The landscape in this aerial photograph is marked by flutes (or drumlins) with wetlands in intervening flutes (sections 34, 35 and 3 and 2) However, the wetlands marked are probably swamp forests and not bogs Fig 4.3.2-4 Wolf Lands 2 (looks like conifer swamp.....not a bog Page 5-227-8 The Mine Site contains localized heterogeneous vertical and horizontal hydraulic conductivities within each soil unit, which also makes the MODFLOW model less effective. Hydraulic conductivities between the different deposits range from 0.00026 to 31 ft/day (PolyMet 2013b).Because there is such a wide range in hydraulic conductivity within the natural geologic formations at the Mine Site, each model layer would contain widely variable hydraulic conductivities. How can an earlier section of the s EIS be so certain that fracture-flow through fractures, joints, or other discontinuities in the bedrock is not likely to be important within the study area? These data are suggestive that such features may affect the hydrology of the wetlands within the NorthMet site. Thus, it was not feasible to model the expected effects of mine dewatering on wetlands in a meaningful way. Prior to conducting the analysis to identify indirect wetland effects resulting from changes in hydrology, bog wetlands within and surrounding the Mine Site were reclassified as either ombrotrophic or minerotrophic. This classification was not supported by the data included within this memorandum with regard to fen indicator species and or the surface water chemistry. This distinction is important because ombrotrophic bogs would likely not be affected by groundwater drawdowns associated with proposed mining operations, whereas more minerotrophic bogs would have a higher likelihood of being affected (Eggers 2011a). Unless the bogs were in fact perched (which is probable but not supported by data included within this memorandum) they would still be connected to underlying groundwater flow systems and could be affected by drawdown. 3. Using the wetlands identified in step 2, wetlands were categorized into minerotrophic(groundwater-fed) and ombrotrophic (precipitation-fed) wetlands using guidance in the Corps Memorandum (CEMVP-OP-R) Distinguishing Between Bogs That Are Entirely Precipitation Driven Versus Those with Some Degree of Mineral Inputs from Groundwater and/or Surface Water Runoff (Eggers 2011b) and evaluating the potential for indirect effects resulting from construction of the water containment system.

The NorthMet EIS does not provide reliable criteria for separating ombrotrophic bogs from minerotrophic fens. The key criteria for distinguishing bogs are a) landform type (surface elevations are always higher toward the interior of a peat deposit than at the peatland margins), b) the absence of fen indicator species, c) surface waters with a pH ≤ 4.2 and Ca concentrations ≤2 mg/l. In contrast, several fen indicator species (e.g. alder, willow, bog birch etc) were listed as components of the "coniferous bog" type within the NorthMet site. The report seems to rely on high cover values for Sphagnum and black spruce, which can characterize poor fens as well as bogs. In addition, it should be kept in mind that most fens have acidic surface waters but fen waters consistently have a pH higher than 4.2 (typically 4.3-6.8 for poor to rich fens). If the authors of this report wish to lump raised bogs and poor fens within the same class they should say so explicitly and not make erroneous inferences about hydrology such as ombrotrophy. The scientific literature is very explicit about this matter and they can check some of the references at the end of this critique. Pg. 5-229 The estimated deposition from fugitive dust emissions was used to identify wetlands that have the potential for water quality changes (e.g., potential for water chemistry changes related to sulfide dust deposition).The estimated deposition from fugitive dust emissions was used to identify a threshold for a negative effect on vegetation. The estimated inputs of the dust, metals, and sulfur to wetlands were evaluated for significance to potential changes in water quality. The receptors of interest were the wetlands that were not identified as directly affected. Dust deposition could have potential impact on both ombrotophic bogs and minerotrophic fens depending on the chemical and mineralogical composition of the dust........either as acidifying agents (in fens) or by the supply of inorganic solutes and nutrients (bogs). Also, overland transport of solutes derived from dust is possible during the flush of spring snowmelt. 5-243 Ombrotrophic coniferous bogs and open bogs were notincluded in the total wetland acreage because their hydrology is supported by precipitation and is not dependent on the size of the watershed. This assumption would only be valid if the bogs in question were perched recharge mounds (which is not documented within this EIS). Otherwise ombrotophic bogs would be connected to groundwater flow systems and responsive to transient and long-term changes in the hydrology of the watershed. Page 5-243 Open and coniferous bog wetlands within and surrounding the Mine Site were

subcategorized as either ombrotrophic (hydrology and mineral inputs entirely from direct precipitation) orminerotrophic (some degree of mineral inputs from groundwater and/or surface water runoff) to determine if the bogs would be affected by groundwater drawdown. Ombrotrophic bogs would likely not be affected by groundwater drawdowns associated with proposed mining operations, whereas more minerotrophic bogs would have a higher likelihood of being affected. This assumption may or may not be valid for the reasons stated above What are multiple analog impact zones? 5-272 For minor groundwater drawdown (ranging from 0.5 to 2 ft), no substantial wetland community changes were identified. Groundwater drawdown would be expected to have a greater effect on smaller than larger wetlands. 5-273 Groundwater modeling cannot reasonably estimate potential indirect wetland effects; therefore ,analog impact zones can provide a reasonable estimate of the extent of potential indirect wetland effects resulting from hydrologic effects. In addition, the evaluation of theoretical groundwater drawdown levels can help estimate what types of potential indirect wetland effects might occur. However, wetland hydrology is a complex mix of precipitation, surface runoff, and in some cases, groundwater. The response of complex natural systems to human disturbances can only be estimated. Therefore, monitoring of wetland hydrology and vegetation communities would occur to document the extent and magnitude of wetland responses (potential indirect effects) to human disturbances. The monitoring plan, developed as part of the Section 404 permit, would be based on those wetlands that have a high likelihood of indirect effects as a result of groundwater drawdown. Permit conditions would likely include an adaptive management plan to account for any additional effects that may be identified in the annual monitoring and reporting. I agree completely 5-274 Another potential impact to consider is the effect of trace metals (e.g. Ni, Mb etc) on nitrogen fixation and methanogenesis since Ni and Mb are key components of the enzymes regulating the N and CH4 cycles in anoxic peat profiles!

5-284 The amount of groundwater discharge to surface water and wetlands between the mine features and the Partridge River would be expected to be minimal relative to the amount of groundwater discharge to the Partridge River itself.

Significant quantities of groundwater are not expected to discharge to the wetlands because of the very low hydraulic conductivities of the underlying peat layers. The leakage/seepage analysis could not indicate or suggest that an effect or adverse effect would occur on wetlands; however, the analysis only indicated those areas that could be conservatively assumed to have a potential indirect effect due to changes in groundwater (PolyMet 2013b). But over longer timescales (e.g. decades) the effect of solute transport could be significant. (e.g. see Siegel, D.I., A.S. Reeve, P.H. Glaser and E. Romanowicz. 1995. Climate-driven flushing of pore water in humified peat . Nature 374: 531-533)

5-298 Wetland hydrology is a complex mix of precipitation, surface runoff, and, in some cases, groundwater. Despite the use of augmentation to mitigate effects, the response of complex natural systems to human disturbances could only be estimated. Therefore, monitoring of wetland hydrology and vegetation communities would be the most appropriate way to document the extent and magnitude of wetland responses to the NorthMet Project Proposed Action. I agree Figure 5.3.1-1 Tracts 1, 2 and 3 Roads Tract 1 - Hay Lake Lands The northeastern boundary of this tract cuts across the crest of a well developed raised bog (=radiating forest patterns):

7. Conclusions This critique raises a number of problems with regard to the wetland section of the NorthMet EIS that can best be resolved by implementing the monitoring plan outlined in section 6 under General Comments. A representative network of relevé plots would be the most effective, economical, and robust approach to monitor any future effects of mining activities on the wetlands within the NorthMet site. This plan would also resolve issues with regard to the occurrence of ombrotrophic peatlands at this area. Any significant impact by mining activites to these wetlands will also produce noticeable changes in the vegetation assemblages within these relevé plots. In order to be most effective it is essential that there plots are established prior to the onset of minining activities and monitored at frequent intervals thereafter by expert botanists.

Eggers 2011

3. Indicator Species of Ombrotrophic Bogs. The MnDNR classification system for native plant communities includes a table of 25 species that are indicators of ombrotrophic bogs. The rationale for this section is not valid. Please note that the MnDNR field guide to the plant communities in northeastern Minnesota explicitly separates bogs from fens by the absence of fen indicator species (MnDNR 2003). No plant species are solely restricted to raised bogs. All of the plant species that grow on bogs also grow on fens and in fact can attain dominance on fens. Examples include Picea mariana (black spruce), Ledum groenlandicum (Labrador Tea), Chamaedaphne calyculata (letherleaf), and various species of Sphagnum. As a result there are no "ombrotrophic bog indicator species" and the reputed "ombrotophic indicators" used in this memorandum cannot distinguish ombrotrophic bogs from minerotrophic fens solely on the basis of their presence or dominance. In the scientific literature ombrotophic bogs are distinguished from minerotrophic fens based on the presence or absence of fen indicator species and different ranges in surface water chemistry. Fen indicator species only occur on peatlands that have surface waters with a pH higher than 4.2 and Ca concentrations higher than 2 mg/l. and are therefore classified as fens. Typical fen indicators include Thuja occidentalis (northern white cedar), Betula pumila var glandulifera (bog birch), Alnus spp (alders), Salix spp (willows) and Juncus stygius that are mentioned as present in the "conifer bog" class within the NorthMet site. In contrast, ombrotophic bogs consistently have surface waters with a pH between 3.6 to 4.2, calcium concentrations less than 2 mg/l, and peat landforms with convex profiles in cross section (i.e. surface elevations that are always higher in the interior of the landform than at the margins. Fen indicator species never grow on such bog sites (although bog landforms larger than 20 km2 can enclose

localized strips of fen called fen water tracks). These criteria produce reliable results that have been field checked by measurements of vegetation assemblages and surface water chemistry (pH, Ca, and specific conductance) across Minnesota and elsewhere across the circumboreal regions (see references). More importantly, they have also been checked by profiles of hydraulic head and pore-water chemistry that document a close linkage between the peatland vegetation assemblages and groundwater flow systems across the Glacial Lake Agassiz region of northern Minnesota (see publications of Glaser and Siegel) and elsewhere (Glaser et al 2004b). These criteria are also consistent with those used by the Minnesota DNR County Biological Survey in the classification of plant communities in northeastern Minnesota [see pages 27, 215-221 in Minnesota Department of Natural Resources (2003) Field Guide to the Native Plant Communities of Minnesota: the Laurentian Mixed Forest Province, Ecological Land Classification Program, Minnesota County Biological Survey, and Natural Heritage and Nongame Research Program, MNDNR , Saint Paul, MN].

MEMORANDUM SUBJECT: Distinguishing Between Bogs That Are Entirely Precipitation Driven Versus Those with Some Degree of Mineral Inputs from Groundwater and/or Surface Water Runoff The authors of this report did not consult the scientific literature on this important subject and therefore reached erroneous conclusions on both the criteria for distinguishing ombrotophic (i.e. solely rain nourished) from minerotrophic (nourished by both rain and waters that have percolated through mineral soil) peatlands and the status of peatlands within the NorthMet site. This subject has been well documented in the scientific literature, which was not referenced in this memorandum. "I noted percent areal cover of Sphagnum mosses – a major factor in distinguishing bogs from other wetland types. I also identified dominant plant species (Table 1)." Please note that this factor is not suitable for distinguishing ombrotophic bogs from minerotophic fens since Sphagum can attain high cover values in poor fens and also in certain spring fen forests, which are located in discharge zones for groundwater (Siegel & Glaser 1987; Glaser et al. 1990, 2004a; Glaser 1987, 1992b). No plant species are solely restricted to ombrotrophic raised bogs and in fact many common bog plants of Minnesota (e.g. Picea mariana, Sphagnum, Chamaedaphne calyculata etc) can also be dominants on fens as well as bogs. Thus the reliance on conjectured "bog-indicator species" represents a false assumption that leads to erroneous results. A good field botanist can usually separate an ombrotophic bog site from a minerotrophic fen site by the presence or absence of fen indicator plants. These species are faithful indicators of the surface water chemistry and inferred hydrology of a peatland site (and this relationship has been rigorously tested by work across northern Minnesota (Siegel & Glaser 1987, Glaser et al 1981,1990, 1997), the Hudson Bay lowland (Glaser 2004b) and elsewhere. However, vegetation surveys on boreal peatland should always be supported by reliable data on the surface water chemistry particularly pH and Ca concentration since these factors have been shown to be most closely related to the vegetation gradient of raised bogs, poor fens, rich fens and extremely rich fens. Another serious problem were the references to water chemistry. The pH range of a true ombrotophic raised bog varies within the narrow range of 3.6-4.2 across northern Minnesota (Glaser et al. 1981, 1990, 1997; Glaser 1987,1992) and also North America (Glaser & Janssens 1986; Glaser 1992b, Glaser et al. 2004a) and the circumboreal zone (e.g. Sjörs 1948, 1964). In contrast, the data tables presented in this report clearly indicate that the sampled peatlands are fens and not bogs. First, the sampled sites all contain fen indicator species. Second, the

surface water chemistry of these sites are all well within the range of rich fens (pH > 5.2). In fact one site is clearly an extremely-rich fen indicative of a groundwater discharge zone. Granted that the method for determining pH (pH strips) was crude. But there can be no way such a peatland can be considered a "classic" example of an ombrotophic raised bog! In retrospect, the members of the wetland working group should have consulted the scientific literature on northern peatlands in Minnesota as well as the treatment of the acid peatland system in the Minnesota Department of Natural Resources (2003). Field Guide to the Native Plant Communities of Minnesota. The Laurentian Mixed Forest Province. Ecological Land Classification Program, Minnesota County Biological Program, MNDNR, Saint Paul,MN pp. 215-221. This treatment defines the pH range of raised bogs as less than 4.2 and also explicitly states that bogs are recognized by the absence of fen indicator species. The system of identifying wetland vegetation types by the presence of plant indicator species may work admirably for wetlands that are not for raised bogs. It is impossible to distinguish ombrotrophic bogs peatlands on the basis of reputed "ombrotophic indicator species." All the species that occur on bogs also grow on fens and some of these species (Picea mariana, Sphagmum, and various ericaceous shrubs) can be dominants on both ombrotophic and minerotrophic peatlands. Raised bogs can only be distinguished only by their landform type, absence of fen indicator species, and surface water chemistry with respect to pH (≤4.2) and Ca concentration (≤2 mg/l). One of the problems with data used in this memorandum and the NorthMet EIS is that the species lists and water chemistry samples were not confined to standardized plots. Thus it is not possible to rule out that the indicators of minerotrophy are outliers confined to the margins of the wetland as suggested in this memorandum. However, based on the pH values listed (which are all well within the range of a rich fen) I suspect that true ombrotrophic peatlands were not sampled for the NorthMet EIS. Caveats: As pointed out in this memorandum the vegetation and water chemistry measurements of peatlands in the NorthMet site were presumably not sampled (or at least reported) according to rigorous standardized methods. The vegetation survey was limited to species lists observed on meanders through specific map polygons and did not employ standardized plots or randomized sample points. Thus the author of this memorandum was uncertain how to evaluate the presence of fen-indicator species on sites that were reputedly identified as ombrotophic raised bogs. In addition, pH strips offer only a coarse measurement of the acidity of the peatland waters. A properly calibrated pH meter should have been used to make these measurements (with calibrations using pH buffers (4.0 and 7.0) performed before and after each measurement). Analyses should also have been conducted for Ca, which is the major cation balancing charge in most natural waters and has been shown to be the most important chemical indicator (along with pH) for distinguishing ombrotrophic from

minerotrophic peatland as well as ranges of poor fen, rich fen, and extremely-rich fen. As discussed in the following paragraph, cover classes reflecting dominance and abundance of ombrotrophic species are more informative compared to a simple presence/absence test. For our purposes, I do not advocate that the presence of species other than those on the MnDNR list of ombrotrophic indicator species rules out ombrotrophic conditions for the plant community as a whole. Rather, dominance and abundance of ombrotrophic species should be applied. There are several reasons for this. One, I recorded all plant species observed including single individuals. Therefore, the presence of a non-ombrotrophic species may have been a single individual plant. Second, some of the species recorded were on the edge or border with uplands or a disturbance (e.g., road). Third, microtopography, including upland “islands” and inclusions of other wetland communities, occur within each polygon resulting in a mosaic of plant associations. Fourth, some polygons are many acres in size so some degree of lumping is unavoidable given the scale and complexity of the Polymet site. Drawing lines across peatland mosaics to delineate breaks between plant communities is a purely artificial exercise that, out of necessity, must include some degree of generalization. Drawing smaller and smaller polygons to tease out patches of different plant communities is not warranted or practical, in my opinion. These assumptions may be reasonable for classifying vegetation assemblages into arbitrary groupings but are not scientifically sound for inferring the hydrologic status of peatlands. An ombrotophic raised bog sensu stricto will not contain any fen indicator species. The occurrence of these fen indicator species unfailingly represents a source of minerogenic water carrying bases from a mineral source that raise the pH of the surface waters above 4.2. The fact that all the pH measurements reported in this memorandum are well within the rich fen range for boreal peatlands indicates that all the peatlands within the NorthMet site are in fact minerotrophic fens and not ombrotophic bogs. It could be that the source of these minerotrophic waters is highly localized within a peatland (e.g. in an internal water track) or only occur at the wetland margins. However, given the small size of these peatlands and the frequency of occasional rock outcrops it seems more likely that these peatlands are in fact rich fens with variable peat thickness. Specific examples illustrate that caution should be used before reading too much into the presence of non ombrotrophic species. For example, Wetland 77 is dominated by tamarack and Labrador tea and has several other MnDNR ombrotrophic bog indicator species. I also recorded two minerotrophic species (cattail [Typha sp.] and blue flag iris [Iris versicolor]). However, the cattail and iris were in the bottom of a dry stream channel that was approximately 2.5-3.0 feet

below the Sphagnum layer, a different microhabitat. The result of deleting the cattail and iris is that 4 of the remaining 5 plant species are MnDNR indicators of ombrotrophic conditions. There is no such thing as an ombrotophic bog species! All the species that grow on raised bogs also grow on fens. In addition the dominant species on ombrotrophic raised bogs can also be dominants on minerortrophic fens This fact has been well established in the scientific literature from the time of Du Rietz and Sjörs (not to mention the classic seminal monograph on raised bogs by C.A. Weber (1902). Furthermore, the pH of the surface waters for this plot was 6, which is well within the fen range and could only be that high if the site was supplied by minerogenic waters with sufficient bases to neutralize the organic acids generated by decaying Sphagnum (e.g. see Siegel et al. 2006). I should add that tamarack can tolerate the acid, nutrient poor environments on raised bogs but it tends to be dominant only in fens. Speckled alder (Alnus incana ssp. rugosa) and bog birch (Betula pumila) are identified by MnDNR(2003) as indicators of minerotrophic conditions in acid peatlands (e.g., “Northern Poor Conifer Swamp,”[APn81], page 221). Both of these species were present in two of the wetlands field inspected (885, 780 )that were dominated by ombrotrophic species and had the most acidic conditions (pH 5.0, 5.25 and 5.5). Wetland 885 was discussed in the field as being a classic example of an ombrotrophic bog. The presence of speckled alder and bog birch in these cases could have been a single or a few individuals, or could have been individuals along the border with uplands, or could have been a microhabitat within the overall ombrotrophic bog. In any event, the presence of these species should not preclude a determination that the plant community as a whole is ombrotrophic. The pH range (5.0-5.7) indicates that this peatland is a rich fen. Alnus incana and Betula pumila var glandulifera are fen-indicator species that never grow on ombrotrophic sites and therefore indicate that this peatland is a rich fen. At best the sampling plan could be considered inadequate to properly classify this site but all the evidence suggests it is a typical rich fen forest. In summary, the parameters used to classify the field inspected wetlands as ombrotrophic or nonombrotrophic were the dominance of Sphagnum mosses, presence of MnDNR ombrotrophic indicators pecies and water chemistry data. Lesser weight was given to the water chemistry data because of the limitations of the testing methods and the few samples taken. These criteria are inadequate to distinguish ombrotrophic from minerotrophic peatlands and are inconsistent with the scientific literature on this topic. Given the uncertainties with respect to sampling (with regard to both the vegetation and the water chemistry) I would strongly recommend re-doing the ground surveys using standardized procedures for both the vegetation and water chemistry) if

the distinction between bogs and fens sensu stricto are important for the NorthMet EIS. At best, the occurrence of these fen indicator species and pH values well within the range typical of rich fens should raise red flags about the use of ombrotrophy in this report. References

Glaser, P.H. 1983. Vegetation patterns in the north Black River peatland, northern Minnesota. Canadian Journal of Botany 61: 2085-2104.

Glaser, P.H. 1987. The ecology of patterned boreal peatlands of northern Minnesota: A community profile. U.S. Fish & Wildlife Service Biological Report 85(7.14), 98 pp.

Glaser, P.H. 1992a. Raised bogs in eastern North America: regional controls on species richness and floristic assemblages. Journal of Ecology 80: 535-554.

Glaser, P.H. 1992b. Vegetation and water chemistry. In H.E. Wright, Jr. and B.A. Coffin (eds.), Patterned Peatlands of Northern Minnesota, University of Minnesota Press, Minneapolis, pp. 15-26

Glaser, P.H. 1992. Rare vascular plants in the patterned peatlands of northern Minnesota. In H.E. Wright, Jr. and B.A. Coffin (eds.), Patterned Peatlands of Northern Minnesota, University of Minnesota Press, Minneapolis, pp. 59-69.

Glaser, P.H. and J.A. Janssens 1986. Raised bogs in eastern North America: transitions in landforms and gross stratigraphy. Canadian Journal of Botany 64: 395-415.

Glaser, P.H., G.A. Wheeler, E. Gorham, and H.E. Wright, Jr. 1981. The patterned peatlands of the Red Lake peatland, northern Minnesota: vegetation, water chemistry, and landforms. Journal of Ecology 69: 575-599.

Glaser, P.H., J.A. Janssens, and D.I. Siegel 1990. The response of vegetation to hydrological and chemical gradients in the Lost River Peatland, northern Minnesota. Journal of Ecology 78: 1021-1048.

Glaser, P.H., Siegel, D.I., Romanowicz, E.A., and Shen, Y.P. 1997. Regional linkages between raised bogs and the climate, groundwater, and landscape features of northwestern Minnesota. Journal of Ecology 85: 3-16

Glaser, P.H., D.I. Siegel, A.S. Reeve, J.A. Janssens, and D.R. Janecky 2004a. Tectonic drivers for vegetation patterning and landscape evolution in the Albany River region of the Hudson Bay Lowlands. Journal of Ecology 92: 1054-1070.

Glaser, P.H., B.C.S. Hansen, D.I. Siegel, A.S. Reeve, and Morin P.J. 2004b. Rates, pathways, and drivers for peatland development in the Hudson Bay Lowlands, northern Ontario. Journal of Ecology.92: 1036-1053.

Glaser, P.H., D.I. Siegel, A.S. Reeve, and J.P. Chanton. 2006. The hydrology of large peat basins in North America, In Peatlands: Basin Evolution and

Depository of Records on Global Environmental and Climatic Changes Martini, I.P., Matinez Cortizas, A., and Chesworth, W. (eds.) Elsevier, Amsterdam.

McNamara, J.P., D.I. Siegel, Glaser, P.H., and R.M. Beck 1992. Hydrologic controls on peatland development in the Malloryville wetland, New York (USA). Journal of Hydrology 140: 279-296.

Minnesota Pollution Control Agency (htpp://www.pca.state.mn.us/index.php

Reeve, A.S., D.I. Siegel, and P.H. Glaser. 2000. Simulating vertical flow in large peatlands. Journal of Hydrology 227: 207-217.

Reeve, A.S., D.I. Siegel, and P.H. Glaser. 2001. Simulating dispersive mixing in large peatlands. Journal of Hydrology 242: 103-114.

Siegel, D.I. and P.H. Glaser 1987. Groundwater flow in a bog-fen complex, Lost River peatland, northern Minnesota. Journal of Ecology 75: 743-754

Siegel, D.I., A.S. Reeve, P.H. Glaser and E. Romanowicz. 1995. Climate-driven flushing of pore water in humified peat . Nature 374: 531-533

Siegel, D. I., P. H. Glaser, J. So, and D. R. Janecky 2006, The dynamic balance between organic acids and circumneutral groundwater in a large boreal peat basin. Journal of Hydrology 320: 421–431.

Sjörs, H. (l948). Myrvegetation i Bergslagen. Acta Phytogeographica Suecica, 21, 1-299.

Sjörs, H. (l950). On the relation between vegetation and electrolytes in North Swedish mire waters. Oikos, 2, 241-258.

Sjörs, H. (l963). Bogs and fens on Attawapiskat River, northern Ontario. Museum of Canada Bulletin, Contributions to Botany, 186, 45-133.

Todd, D.K. and L.W. Mays (2004) Groundwater Hydrology. 3rd edition. Wilely & Sons, NY.

Weber, C. A. (1902), U¨ ber die Vegetation und Entstehung des Hochmoors von Augstumal im Memeldelta mit vergleichenden Ausblicken auf andere Hochmoore der Erde, Paul Parey, Berlin.

Winter, T.C. 1999. Relation of streams, lakes, and wetlands to groundwater flow systems. Hydrogeology Journal (1999) 7:28–45.

Winter, T.C. J.W. Harvey, O.L. Franke, and W.M. Alley 1998. Ground Water And Surface Water A Single Resource, USGS Circular 1139.

Comments by Paul Glaser on Indirect Wetland Impacts at the Mine Site (memorandum from Barr Engineering).

The memorandum on "Indirect Wetland Impacts at the Mine Site" embraces an assumption that the NorthMet site wetlands support "perched" water tables and will therefore be relatively unaffected by mining operations. Although this assumption may be valid it is not supported by the field data presented within this document or the NorthMet EIS.

First, it cannot be assumed that the deeper peat strata within the NorthMet site have such a low hydraulic conductivity that these peat layers function as aquitards, essentially preventing the vertical and lateral movements of pore fluids. Extensive hydrogeological investigations in the Glacial Lake Agassiz peatlands of northwestern Minnesota, for example have documented that a) the hydraulic conductivity of deep peat remains sufficiently high within the

deeper peat to support significant vertical or lateral movement of both pore fluids and solutes even in peat profiles more than 4 m (5.2') thick,

b) these investigations further documented a direct hydraulic connection between these deep peat deposits and the underlying mineral substratum,

c) vertical transport of both pore waters and solutes has been documented by measurements of hydraulic head gradients and profiles of dissolved solutes (e.g. cations) and isotopes,

c) coupled solute transport-groundwater models further demonstrate that the pore fluids can be completely flushed in deep peat profiles by downwardly moving recharge (i.e. precipitation) or upwelling groundwater within the time span of decades or less.

Second, at least some of the wetlands within the study area are underlain by relatively permeable glacial deposits with a substantial fraction of coarse-grained materials (e.g. sand and gravels). Such deposits have a wide range of permeability and have been demonstrated to support vertical transport of both groundwater and solutes in the Glacial Lake Agassiz peatlands and elsewhere.

Third, it is unfortunate that the assumed existence of perched water tables and aquitards are not supported by direct evidence from a) nests of piezometers inserted within and below the peat deposits, b) profiles of solute concentrations within the pore waters, and c) in situ determinations of hydraulic conductivity with Horslev slug tests,

Fourth, It should be kept in mind that the pumping required to dewater a large mine peat will probably exceed that of the pumping tests conducted in these assessment studies by many orders of magnitude. Therefore, these small-scale pumping tests cannot verify the impact of mining operations on wetlands within the NorthMet site.

In light of the uncertainties regarding the hydrogeology of the NorthMet site (e.g. permeabilities of the glacial deposits and bedrock, distribution of fractures in the

bedrock, occurrence of perched water tables in wetlands) the best approach to monitor potential impacts to wetlands within the NorthMet site would be to establish a network of permanent vegetation plots prior to the onset of mining operations. The vegetation in peatlands is very sensitive to water levels and surface water chemistry so any significant impact of the proposed mining operations would produce a major change in the vegetation assemblages within these plots. For example a significant drop in the water table would shift the vegetation assemblages to favor the growth of woody shrubs and trees, whereas a rising water levels would drown the trees, suppress the growth of woody shrubs, and lead to the dominance of sedges