Monitoring Wetland Condition of the Milk River WatershedBlackfeet Reservation, Montana

Prepared for the US Environmental Protection Agency, Region 8, Denver

Tara Luna, Mary Clare Weatherwax, and George Running Wolf, III

January 2016

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Wetland Monitoring Project Overview

The Blackfeet Tribe has adopted a “No-net loss of wetlands of the Blackfeet Indian Reservation” as the governing policy for wetland resources within the 1.5 million acre Reservation. This policy is in accordance with federal regulatory standards and policies. The Blackfeet Tribe is developing a comprehensive Wetlands Program to preserve and protect wetland and riparian resources on the Reservation in compliance with the United States Environmental Protection Agency’s (USEPA’s) Four Core Elements of Developing a Wetlands Program.

This report contains the results from the 2013 rotating watershed wetland monitoring and assessment (M&A) study of the Blackfeet Reservation. Wetland program work has further developed wetland regulatory standards and enforcement of those standards grounded in the results from previous year’s wetland ecological integrity monitoring. Monitoring and regulatory project work has resulted in the Tribe identifying specific wetlands and wetland complexes for restoration and conservation efforts.

The Milk River Watershed Area

The Milk River originates entirely on the Blackfeet Reservation. The North Fork originates from Hudson Bay Divide, northeast of Duck Lake, while the Middle Fork and Dry Fork originate from the eastern and southern slopes of Saint Mary Ridge. The South Fork originates from the southeastern slope of White Calf Mountain. The Middle and Dry Fork meet in the central portion of the watershed, while the South Fork joins the Middle Fork northeast of Browning. From there the Milk River continues across the northeastern portion of the Reservation, before crossing the Canadian border just east of Del Bonita. The North Fork crosses the Canadian border approximately 17 miles east of the Port of Piegan and the North Fork joins with the main stem of the Milk River in Alberta, Canada before running southeast again and back into northern Montana. See map Figure 1.

Major tributaries include Livermore, Fox, Kennedy, and Woman Creeks. Major lakes in the Milk Watershed include Horse, Toad and Croff Lakes. Headwaters areas of this river are crucial to local and regional water supplies across the Reservation, in Alberta, and across north-central Montana.

Geology and Soils

The Milk River originates from the Hudson Bay Divide, ranging in elevation from 1829 m (6,000 ft) near the headwaters of the Middle and South Forks to 1219 m (4,000 ft) on the northeastern edge of the watershed. Headwaters are influenced by Pre-Cambrian sedimentary bedrock that occurs above the Lewis Over-Thrust Fault near the western edge of the Reservation. Pre-Cambrian bedrock in this drainage is predominately limestone, influencing water chemistry and the prevalence of calcareous and alkaline influenced wetland plant communities and ecosystems in this area of the watershed.

The central and eastern sections of the Milk River watershed consist of rolling topography with numerous depressional wetlands, lakes, coulees and creeks feeding into the Milk River and its

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main forks. Moraine deposits and numerous depressional wetlands formed by glaciation occur throughout the area, but are especially concentrated in the northeastern section of the watershed. The bedrock of Hudson Bay Divide, along edges and ridges of the watershed, is overlain by Quaternary-age unconsolidated deposits of cobbles and Tertiary-age gravels (Cannon 1996). Younger deposits of Pleistocene and older Pliocene gravels occur in pediments and terraces near Hudson Bay Divide. Numerous deposits of younger and older gravels and cobbles, as well as boulders occur throughout the watershed. Cretaceous sedimentary formations (80 million years ago (mya)) occur within the valleys and plains of the Reservation. Sandstone and sandy shale deposits occur above coulees and breaks along the Milk River near the eastern edge of the Reservation. Quaternary age alluvium is found along all branches of the Milk River within the Reservation boundary.

Sampled wetland soils in the Milk River watershed area typically have an organic layer that ranges from 14-16 cm overlying silty gravels and cobbles to 20 to 40 cm overlying predominately clays, clay loams or silty clays. Clay layers often contain significant cobble or gravels, depending on the location within the watershed. Histic soil peat layers range from 25 to 35 cm deep in forested riverine fens.

Climate - Recent Climate

The climate gradient across the Milk River watershed is highly variable due to proximity to the Continental Divide, near the headwaters, and more semi-arid climate characteristic of the northern Great Plains on the northeastern edge of the Reservation. Annual precipitation averages range from 164 to 305 cm (65 to 120.3 in) in the mountains to 36 to 38 cm (14 to 15 in) on the eastern edge of the watershed (Western Regional Climate Center 2015). Mean January low temperatures range from -11° C (13.1°F) at Saint Mary, northwest of Hudson Bay Divide and -14° C (6.7 °F) at Del Bonita and Santa Rita. Mean July temperatures range from 23.5°C (74.4 °F) at Saint Mary, 31°C (87.7 °F) at Del Bonita and 25.4°C (77.7°F) at Santa Rita (Western Regional Climate Center 2010). Concerns over global warming that include increasing annual temperatures, decreasing snowpack and other variables are factors concerning water management in the Milk River watershed.

Water and Hydrology

Groundwater discharge, originating at Hudson Bay Divide, forms the head of the Milk River and its tributaries. Groundwater discharge in headwater areas occurs in association with gravel and cobble deposits or gravel deposits within glacial till overlying bedrock. Discharge occurs where gravel beds intersect bedrock, typically occurs on ridges and slopes below Reservation peaks and at the base of Milk River Ridge and the foothills along the North, South and Middle Fork and their tributaries. Seeps and springs occur from gravel beds, pediments and terrace deposits and higher elevation late snow melt beds that recharge shallow aquifers. Annual snowpack and summer precipitation contribute to the watershed and shallow groundwater aquifers. Groundwater fed potholes and kettle ponds are important to aquifer recharge. Alluvium gravel terraces and pediments, till and outwash occurring above impermeable bedrock are the only

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sources of potable water in some areas of the watershed, where aquifers occur above bedrock (Cannon 1996).

Vegetation

The main tributaries and branches of the Milk are bordered by Populus balsaminifera (black cottonwood) forests and Salix (willow) dominated shrublands in the valley bottoms of the Reservation. Abies lasiocarpa/Picea engelmannii (subalpine fir/Engelmann spruce) forests border groundwater discharge points of the South Fork below White Calf Mountain. Mixed Populus tremuloides (quaking aspen) or conifer forests on the eastern slopes of Hudson Bay are common near the head of the Dry, Middle and North Forks. Groundwater fed wet deciduous and coniferous forest types, both which are considered to be extremely rare to rare, are found near the headwaters of Fox Creek. Beaver dams and beaver influenced fen/riparian complexes, which are often species rich or contain rare wetland flora, are found in the South Fork area. Stands of Populus balsamnifera mixed with Populus angustifolia (narrowleaf cottonwood) floodplain forests and occasionally stands of P. tremuloides in the North Fork, are found in the northeastern portion of the watershed. Salix dominated communities are common along all tributaries and are heavily influenced by beaver activity.

Fauna

Reservation wetlands and riparian areas are crucial to the maintenance, migratory patterns and dispersal of all resident and migratory wildlife species known to occur in the Northern Rocky Mountain ecosystem, as well as fauna found in the Northwestern Great Plains Region. Over 65% of all known native birds and fish and over 80% of all native mammals known from the state occur on the Reservation. A total of 109 faunal species within the Blackfeet Indian Reservation are Montana Species of Concern.

Federally protected species such as grizzly bear, wolverine, bald eagle, golden eagle, lynx and grey wolf occur within the Milk River watershed of the Reservation. Riparian corridors are used by grizzly bears that travel further east onto the plains. Headwater riparian areas are heavily influenced by beavers. Antelope, jackrabbit, thirteen-lined ground squirrel, Richardson’s ground squirrel, and swift fox are found in the central and eastern sections of the watershed.

Bird life of the Reservation is especially rich and highly dependent on Reservation wetlands, with 66% of all species known in Montana found within the Reservation. Raptors, songbirds and waterfowl utilize the wide diversity of forested and grassland habitats at a range of elevations.

Depressional wetlands located within aspen parkland and prairie in the central and eastern portions of the drainage are critically important habitat for migratory waterfowl and shorebirds, as well as supporting a high diversity of migratory songbirds and raptors. Larger depressional wetlands are used by such species as trumpeter swans, tundra swans, bald eagles, and golden eagles. Thousands of birds migrate through the area during spring and fall migrations. Many prairie wetlands support nesting populations of common and rare wetland bird species, while forested wetlands support many additional common and rare songbirds and raptors.

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Land use impacts elsewhere in the western Prairie Pothole region, as well as increasing impacts due to global warming on the hydrology of these wetlands, emphasizes the critical importance of these wetlands for future wildlife conservation efforts, as well as providing habitat for migratory birds that will shift migratory corridors and patterns to areas of water and habitat availability.

Recent Fire History

In 1994 the Livermore Fire burned 1,080 acres in the Milk River watershed. Two major wildfires occurred within the Milk Watershed in the past 14 years: the Fox Creek Fire (2002) and the Red Eagle Fire (2006). The Fox Creek Fire began as a lightning strike during an exceptionally hot and dry summer, burning several thousand acres in the Saint Mary and Milk River watersheds. The Red Eagle Fire started in Glacier National Park and burned a total of several thousand acres of forest within the Middle, Dry and South Forks of the Milk River drainages, removing a significant portion of Blackfeet conifer dominated forests that buffer the upper Milk River drainage. Forest types that burned during these events include aspen/ cottonwood deciduous forests, Douglas-fir, lodgepole pine, and spruce-subalpine fir. Some wetland and riparian areas occurring on toe-slopes were affected by post-fire erosion in surrounding burned uplands, causing stream sedimentation. Both fires occurred during an extreme drought cycle of the early to mid-2000’s that affected other areas of the western United States and Canada.

Land Use

Land use includes livestock grazing and rural residences on native prairie and forests on the western third of the watershed. The western region receives high tourist traffic during summer months and is important for local tourism-derived income. Local hunting and sport fishing are important sources of local Tribal income. Dryland farming, primarily wheat and some barley, as well as introduced and native hay production occur mostly on the middle and eastern sections of the watershed. The northeastern portion of the Milk River watershed contains some land owned by the Big Sky Hutterite Colony. The Hutterites produce wheat and barley, as well as cattle, swine and poultry. The Reagan Oil Field, bordering the International border, also in the northeastern section, has been developed for oil and gas production. More extensive development occurred during the mid-1980’s, and additional exploration and development has occurred during the past 10 years.

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Figure 1.

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Monitoring Study Objectives

Objectives included: 1) establishing baseline ecological integrity assessments for a range of wetland ecosystem types per Reservation watershed, identifying the type, scope and intensity of disturbances affecting these wetlands; 2) locating and identifying reference condition wetlands for conservation and protection and that serve as local benchmarks for wetland restoration sites; 3) identifying wetlands for future restoration work; 4) collecting wetland water quality data; and 5) sampling wetland macro-invertebrate diversity and community composition in the watershed.

Methodology

Three Tribal personnel were trained during mid June 2013 using the Montana Natural Heritage Program’s (MNHP’s) Ecological Integrity Assessment methodology (2013 version). The protocol uses three levels of analysis: Level 1 - Landscape Level Analysis; Level 2 - Qualitative Rapid Field Assessment and Level 3 - Intensive Vegetation and Disturbance Indicator Assessments. The Tribe utilized the Level 2 and Level 3 assessments to assess wetlands condition in the Milk River watershed.

Site Selection

Sites were selected by probabilistic random sampling with sample points provided by MNHP. Original target coordinates were used whenever possible, although five sites were shifted within 60 m of the original target coordinates. A total of six sites were selected that were greater than 60 m from target coordinates due to lack of accessibility. GPS and photo points were taken at each wetland assessment area and of the vegetation plot. One wetland soil core was collected per site to examine wetland soil layer features at each site. One wetland vegetation quadrat was established at eight sites to measure structure, canopy cover and composition of wetland vegetation, using methodology described in MNHP protocol.

Level 2 and Level 3 vegetation sampling and wetland assessments were done over a representative sample of wetland systems occurring across the watershed, ranging from beaver influenced, fen/montane riparian complexes near the South Fork of the Milk headwaters to closed depressions and Great Plains prairie potholes in the eastern section near the Canadian border.

Data Entry and Analysis

Data was entered into a Microsoft (MS) Access Database (2007) for analysis. Data is stored on computers, laptops and on external hard drives.

Results

Level 2 Rapid Qualitative

A total of 29 Level 2 assessments were conducted in the Milk River Watershed during 2013. Landscape, Physiochemical, Hydrologic and Vegetation metrics and disturbances were

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calculated to arrive at an overall mean EIA score for each wetland type. Total mean scores per wetland system type are shown in Table 1.

Table 1: Mean EIA scores in the Milk River Watershed

Wetland Ecological System No. Mean

Great Plains Prairie Pothole 10 82.4

Western Great Plains Closed Depression Wetland 2 76

Northern Rocky Mountain Forested Pothole/Vernal Pool 1 66.9

North American Western Marsh 2 85.0

Northwest Great Plains Riparian Floodplain Wet Meadow 3 84.6

Rocky Mountain Subalpine-Montane Fen/Riparian Shrubland 3 88.5

Rocky Mountain Subalpine-Montane Riparian Shrubland 8 81.7

Physiochemical and Landscape

Level 2 hydrologic metrics (hydroperiod, alteration and connectivity) had the highest score of all metrics measured, followed by physio-chemical (water quality, soil surface integrity) and landscape metrics (connectivity, buffer width, length, condition, soils, trash). All sample sites scored high in surface water connectivity, and only two sites exhibited hydrologic alterations or hydroperiods. Soil surface integrity scored lower than water quality, due to grazing impacts. Only one wetland assessment site was located within agricultural land.

Buffer condition, however, averaged lowest of the landscape metrics used, due to frequency of exotic grasses and noxious weed cover and grazing impacts. Livestock grazing was the most frequent disturbance within wetlands and upland buffers. Scope and impact of livestock grazing in wetlands were restricted to moderate (10-25%) in all AA sites, with GP potholes more heavily impacted compared to low to moderate impacts in surrounding 200 m upland buffers.

Vegetation

Ninety five percent of the 29 wetlands surveyed contained native vegetation with cover values great than 95 percent. Cirsium arvense (Canada thistle) within the Assessment Area (AA) and Centaurea maculosa (spotted knapweed) in the upland buffer were the most frequently encountered noxious species. Invasive graminoids cover values (>5%) were also encountered at 23% of wetland sites, with Alopecurus pratensis (meadow foxtail) or Alopecurus arundinaceus

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(Garrison’s creeping foxtail) being most frequent, followed by Phleum pratense (timothy) and Poa pratensis (Kentucky bluegrass).

Level 3 Intensive Vegetation

Floristic Quality Assessments (FQI) scores were assigned by calculating the coefficients of conservatism values (C values) (Pipp 2015), ranging in score from 0-1 (exotics) to 10 (native taxa with high specificity), for taxa occurring in plots, in eight sampled wetlands. The Floristic Quality Index (FQI) is calculated using the following formula:

Where is the mean C-value and N is the number of native species within the entire plot.

The FQI was calculated to a score that includes non-native species by the following:

Mean Floristic Quality Assessment scores were calculated for the Level 3 assessment sites. Results are shown in Table 2.

Table 2: Mean FQI scores for eight sites in the Milk River Watershed

Wetland Ecological System No. MeanFQI

Min Max

Great Plains Prairie Pothole 2 40.4 37.5 43.3

Closed Depression 1 33.6 - 33.6North American Emergent Marsh 1 53.6 - 53.6Rocky Mountain Riparian Shrubland/Fen 2 59.6 50.3 69.0

Rocky Mountain Riparian 1 57.2 57.2Great Plains Riparian Floodplain Wet Meadow 1 35.2 - 35.2

Beaver influenced, Palustrine Scrub-Shrub (PSS) associations, occurring in association with riverine fens along the South Fork of the Milk River, contain an average of 63 (r 57-69) plant taxa, while PSS associations not associated with fens contain two-thirds fewer taxa (an average of 22).

The numerous Great Plains prairie potholes and closed depressions of the watershed contain on average three Palustrine Emergent (PEM) herbaceous associations. Emergent communities in beaver ponds and marshes with bordering fen vegetation contain on average three taxa, while emergent Great Plains potholes contain on average two taxa.

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Salix boothii/Carex utriculata (Booth’s willow/beaked sedge) was the most frequently encountered plant association near the headwaters of the Milk River, followed by Salix bebbiana (Bebb’s willow)/mesic graminoids. Salix bebbiana/Carex utriculata and Salix bebbiana/mixed graminoids or mesic forbs typically occurs as a narrow band on the perimeter of riverine and riparian sites, and is the most frequently encountered scrub-shrub association found in forested potholes and Great Plains potholes occurring near the mountains. The most commonly encountered emergent plant community in all sites was Carex utriculata, followed by Carex aquatilis/Deschampsia caespitosa (water sedge/tufted hairgrass).

Discussion

Wetlands of the Milk River watershed have higher Wetland Ecological Integrity Scores than wetlands found east of the Reservation due to large, intact native buffers, lower (<10%) incidence of wetland hydrologic alteration, minimal paved and secondary roads within the AA, and the absence of intensive logging and agriculture other than haying.

Livestock grazing is the most frequent disturbance, in scope and severity, both in wetlands and natural buffers. At the higher elevation sites sampled, beaver complexes were relatively undisturbed by livestock grazing and contained few exotic species, presumably due to thick willow brush surrounding these wetlands preventing extensive livestock access. In valley bottoms near Montana Highway 89, beaver influenced riparian areas were more heavily impacted by livestock.

One Great Plains prairie pothole sampled has remained dry for many years since the National Wetlands Inventory (NWI) mapping, and has been invaded by upland species (Festuca scabrella, rough fescue) with only residual cover of wetland facultative (FAC) species.

Application of Results

Results and extensive field work by the 2013 field crew have identified excellent condition wetlands, some of which are critical headwater wetlands of the Milk River, as well as rare forested wetland community types and fens. Excellent condition Plains riparian floodplain forests with extensive natural regeneration are found along all the forks of the Milk River. Further downstream beyond the Reservation, high quality cottonwood floodplain forests are rare due to dams, extensive grazing and invasive woody plants.

The Milk River watershed of the Blackfeet Reservation is unique in containing these high quality riparian sites that have become rare in the Upper Missouri watershed. Several conservation easement programs are available to landowners. Previous easements have been in place on Livermore Creek and other wetlands of the Milk watershed. Recommended conservation easement sites for wetlands and associated upland buffers, occurring on Tribal, allotted and fee lands, are described in the supplemental report “Wetland and Riparian Conservation, Blackfeet Reservation” (Luna 2015).

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Recommendations for Future Wetland Monitoring Assessments

It is recommended that additional cottonwood dominated forests along the Milk River and its tributaries are more intensively surveyed, assessed and inventoried during future monitoring work. Additional prairie potholes in the central and northeastern sections can be evaluated for species composition and overall quality, and to further restoration and conservation objectives in the eastern portion of the watershed. Protecting fens and rare forested wetland community types during the reconstruction of Highway 89 is necessary, to conserve the range of wetland biodiversity of the watershed and improve water quality and flow in the headwater areas of the Milk River watershed.

References

Cannon, MR. US Geological Service. 1996. Geology and Groundwater Map of the Blackfeet Reservation, Northwestern Montana.

Flora of North America, (FNA). 1993-2011. Published volumes and online treatments. Oxford University Press. (London and New York).

Hitchcock CL and Cronquist A. 1987. Flora of the Pacific Northwest. University of Washington Press. Seattle (WA) 343 p. ISBN 0-295-95273

Lesica P. 2012. Manual of Montana Vascular Plants. Britt Press. Fort Worth (TX) 771 p. ISBN: 13-978-1889878-39-3

Luna, T. 2015. Wetland and Riparian Conservation, Blackfeet Reservation. Wetlands Conservation Report. Blackfeet Environmental Office. Browning, MT. Prepared for the US Environmental Protection Agency.

Montana Natural Heritage Program. 2014. Wetland Assessment Protocol. Helena, MT. 55 pages.

Pipp, A. 2015. Coefficients of Conservatism for the Flora of Montana. Part 1. Montana Natural Heritage Program. Helena, MT. Prepared for the MT Dept. of Environmental Quality. 60 p.

Western Regional Climate Center. 2015. (URL: http://www.wrcc.dri.edu/)

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