WATERSHED PROTECTION OF THE ST. LAWRENCE RIVER WATERSHED WITH SPECIAL CONSIDERATION TO
LARGE TRACTS OF LAND
PART TWO: THE SALMON/TROUT, RAQUETTE, AND GRASSE WATERSHEDS
On this page:
The total watershed area calculated from mapping the wetlands and sub-watersheds of the Salmon/Trout, Raquette and Grasse Watersheds, was 961,218.8 acres (388,993.0 ha); the watershed area within the Park was 955,064.7 acres (386,501.6 ha). The difference between the totals results from the small areas of some sub-watersheds that were mapped outside of the Park because they drain back into the Park and thus influence the hydrology and water quality of the Park.
A total of 708 sub-watersheds were mapped for the project area, including 17 that were determined to be internally draining, 38 that are riverine watersheds, and 653 pond watersheds (Figure 4). The sub-watersheds ranged in size from a minimum of 4.0 acres (1.6 ha) to a maximum of 593,359.0 acres (240124.2 ha) (Table 1). The 17 internally-draining sub-watersheds constitute only 2% of the total sub-watersheds, in comparison with 9% of the sub-watersheds of the St. Regis watershed found to drain internally. Regionalized watersheds, made up of flow path groupings of sub-watersheds, were created using the ArcInfo watershed regionalization AML (Appendix 8, Primack 1988). 9 regional watersheds were created in the Raquette/Grasse watershed and 10 were created in the Salmon/Trout. There were 3 SCS 11-digit watersheds (USDA/SCS 1980) contained within the Salmon/Trout watershed and 17 within the Raquette/Grasse (Figures 5 and 6).
Within the project area of 961,218.8 acres (388,993.0 ha), 122,711.3 acres (49,659.7 ha) were mapped as wetlands; wetlands, therefore, constitute 12.8% of the St. Lawrence II watershed's surface area (Figure 7). This is a slightly smaller percentage than the 15.4% wetland cover in the St. Regis watershed (Halasz et al. 2000) but both are higher than the 7.0% mapped in the Upper Hudson (Primack et al. 2000). Within the St. Lawrence Part II project area, an additional 5.7% percent of the watershed area is lacustrine or riverine open water.
14 different NWI wetland cover types, including palustrine open water, were used to classify the wetland polygons for the project; each polygon was labeled with up to two cover types, which are described in Table 2.
Out of these 14 cover types, three were most prevalent (Table 3): FO4, representing needle-leaved evergreen forested wetlands, was used to label 29.1% of the wetland area mapped; SS4, representing needle-leaved evergreen scrub shrub wetlands, appeared in the labels of 26.3% of the wetland area; SS1, Broad-leaved deciduous scrub shrub, was used for 22.2% of the wetland area. All other cover types appeared in the labels of less than 10% of the wetland area.
Class1 and Class2 labels and various water regime and special modifiers (NWI legend in Appendix 2) combined to make 250 different wetland labels in the project area. Several labels were most common, both in terms of area and in terms of number of occurrences (Tables 4 and 5, and Appendix 4). PFO4/SS4B was the label used for nearly a quarter of the wetland area in the watershed at 21.2%. This label was also the second most common in terms of number of occurrences. The label PSS1/EM1E accounted for an additional 9.7% of the wetland area, and PFO4B yet another 9.4%. The latter, despite being third most common in area, was most common overall in terms of number of occurrences, with a total of 4,048 polygons in the watershed. Finally, the label POWHb, designating bever-modified open water wetlands, ranked sixth in terms of wetland area but third in terms of number of occurrences.
For this project, as with several preceding wetlands mapping efforts in the Park, a special modifier, "b," was employed for wetlands influenced by beaver activity. This modifier was appended to approximately a quarter, 24.5%, of the wetland polygons in the watershed. Those same beaver-modified wetlands accounted for 19.0% of the wetland area in the watershed. The "b" modifier was most common, by number, in wetlands with Class1 labels of POW, SS1, EM1, and FO5 (Table 6). Fully 95.4% of the number polygons with FO5 as the Class1 label had the special beaver modifier, and 93.8% of the polygons with SS5 as Class1. Among wetlands with POW or EM1 as the Class1 label the "b" modifier was slightly less common by number, accounting for approximately three-quarters and half of the polygons, respectively.
A high proportion of the wetlands proved to have saturated water regimes. A total of 89.5% of the wetland area in the watershed had either a saturated (B) or a seasonally flooded-saturated (E) regime modifier (Table 7). Together, these modifiers were appended to 109,606.3 acres (44,356.16 ha) of wetland in the watershed. The 89.5% of wetland area that is saturated in this project area can be compared to the 72.4% of wetland area in the St. Regis watershed that is saturated (Halasz et al. 2000), 85% of Upper Hudson wetland area (Primack et al. 2000), and 74% of Oswegatchie-Black (Roy et al. 1996).
State Land Unit Management Planning
The maps that were provided to DEC Forest Preserve Managers (Figures 8, 9, 10) are particularly important in providing habitat information for boreal species that are a special consideration in developing UMPs. The following interpretation was provided to DEC staff along with the map of cover type wetlands that will be used in the Unit Management Plan for the Bog River Complex.
The most common cover types, based on area and also number of wetlands, are SS1 and FO4. From the map, we can see that SS1 wetlands mostly occur along river courses. Large SS3 (leatherleaf dominated peatlands) areas can be seen on the north end and southeastern shore of Hitchins Pond. These SS3 areas may serve as important habitat connections with the large peatlands to the north around Massawepie Lake and those to the south by Round Lake, for species such as the spruce grouse, three-toed woodpecker, black-backed woodpecker, boreal chickadee, and palm warbler. The occurrence of spruce grouse in this area is substantiated in the New York Natural Heritage Program database of element occurrences.
Along with the wetlands maps and interpretation information, DEC staff were provided with a table (Table 8) showing the distribution of the different cover types and textual interpretation highlighting the important ecological and habitat implications of the data.
Discussion: Large Wetlands
The St. Lawrence Watershed is host to an extraordinary number of large wetlands due to the hydrogeomorphology created by glaciation. Many of these large wetlands are associated with the lowland river channels that drain the upper elevations of the Adirondack Mountains. In the St. Regis report, we began an analysis of naming, measuring, and describing the largest of the St. Lawrence Watershed wetlands. This analysis was summarized in a table in the St. Regis report (A HREF="http://www.northnet.org/adirondackparkagency/cdrom/stregis/report/reportpg2.html#tab1">Table 1 in Halasz et al. 2000). With the completion of mapping for the St. Lawrence II project, the earlier analysis was able to be updated (Table 9) with:
Some of the peatlands, such as Spring Pond Bog, actually span watershed divides and couldn't be completely measured until St. Lawrence II was complete. Figure 11 shows a map of the location of these large wetlands in the St. Lawrence watershed.
This inventory of large wetlands should be used to direct future wetland research efforts (or updates of previous research summarized in the Literature Survey section of this report).
Continue to next section of St. Lawrence II Report: Appendix1 - List of Quadrangles
Return to table of contents