China Lake Characterisitcs
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CHINA LAKE CHARACTERISITCS WATERSHED DESCRIPTION The China Lake watershed is located in Kennebec County, Maine, and is situated within the townships of China, Vassalboro, and Albion (Figure 8). The lake is classified by the Maine Information Display Analysis System (MIDAS) as MIDAS #5448 (PEARL 2005a). This classification system assigns unique four-digit codes to identify all lakes and ponds in Maine. China Lake is located 44.25° N and 69.33° W, at an elevation of 59.1 m (194 ft), and covers a surface area of 1,604 ha (3,963 acres) (PEARL 2005a). China is classified geographically as a two basin lake, with an East Basin and West Basin (PEARL 2005a). Bathymetrically, China Lake is described as a three basin lake, with three deep holes forming the western, southeastern, and northeastern basins (Manthey, pers. comm.). China Lake has an average depth of 10.1 m (33.1 ft), a maximum depth of 28.2 m (92.4 ft), and a volume of 120,001,704 m3 (97,286.4 acre- ft) (PEARL 2005a). The water within China Lake flows from input to output at an annual rate of 0.35 flushes per year. There are several small islands within China Lake, most notably Indian Island, Green Island, Bradley Island, and Moody Island. China Lake is dimictic, experiencing thermal stratification in the summer with turnovers occurring each spring and fall. Algal blooms have been reported yearly since 1983 and the Maine Department of Environmental Protection (MDEP) currently describes China Lake as a “frequently blooming” lake. This classification means that the lake commonly experiences late summer and early fall reductions in water transparency due to algal blooms (MDEP 2005a). The China Lake watershed boundary used in this study was obtained from the Maine Office of GIS (MEGIS), and includes the direct drainage area of China Lake and the small sub- watersheds of Evans Pond and Hunter Brook (MEGIS 2005). The drainage area of the China Lake watershed (not including China Lake itself) covers an area of 6,911 ha (17,077 acres). The topography within the 6,911 ha of the watershed is a mixture of rolling hills surrounding wetland and pond basins, each of which drains into China Lake. The highest of these hills, Barmeter Hill, is 197 m (646 ft) in elevation and situated on the southeast edge of the watershed boundary. Colby College: China Lake Report 37 Albion Vassalboro China Figure 8. Location of China Lake and the China Lake Watershed within the towns of Chin a, Vassalboro, and Albion, ME. China Lake is a naturally formed, glacial-basin lake that was enlarged by raising dam outflow levels in 1969. Originally constructed during the Civil War era, the dam at the outflow of China Lake at Vassalboro was restructured by MDEP in 1969, raising the lake level approximately 1.2 m (4 ft). The outflow of the dam is currently under the management of the Town of Vassalboro, but will be transferred to the Kennebec Water District in 2006 (Manthey, pers. comm.). The Kennebec Water District gained control of the dam because the West Basin serves as the water supply for the greater Fairfield, Oakland, Vassalboro, Waterville, and Winslow area. The majority of the water input to China Lake comes from Hunter brook via the Muldoon (wetlands) at the northern terminus of the lake, Clark Brook in the southeastern portion of the East Basin, and inflow from Jones Brook at the southern terminus of the lake. There are several other small unnamed tributaries along the eastern shore of the East Basin, and northern shore of the West Basin. However, due to their ephemeral nature, the flows of the smaller tributaries were minor or nonexistent during the field period of the study. The waters of China Lake flow north to south in the East Basin, and east to west in the West Basin, where the Outlet Stream is the Colby College: China Lake Report 38 only distributary for China Lake. The Outlet Stream ultimately empties into the Sebasticook River, and shortly thereafter the Sebasticook empties into the lower Kennebec River (PEARL 2005a; see Analytical Procedure and Analysis: Water Budget). GEOLOGICAL AND HYDROLOGICAL PERSPECTIVE During the Pleistocene Epoch (25,000 to 20,000 years ago), Maine was covered completely by the Laurentide Ice Sheet, which extended from Labrador and Newfoundland through New England, reaching its southernmost point near Long Island, New York at the peak of glaciation (Marvinney and Thompson 2000). The ice sheet moved in a south-southeastern direction and spread beyond the present coast of Maine and onto the continental shelf. The motion of the ice shaped the landscape of Maine as sediments were lifted and deposited, previous waterways were destroyed, and hundreds of new lakes and ponds were left in their place following the recession of the ice sheet (Marvinney and Thompson 2000). Approximately 21,000 years ago, climatic warming began to melt the Laurentide ice sheet. By 10,000 years ago, the ice sheet had nearly completely receded from Maine (Davis et al. 1978, Marvinney and Thompson 2000). Glacial recession caused further deposition of sediments, leaving a glaciomarine clay-silt and glacial till substrate over bedrock throughout Maine. This substrate now characterizes the typical lake basin in the state, most of which have a southeasterly orientation due to the direction of glacial movement up the coast (Davis et al. 1978). These lakes are considered young by geologic standards, having formed less than 10,000 years ago, and many are naturally nutrient poor because of underlying characteristic substrate. This combination of young age and naturally low nutrient levels would predict that most Maine lakes would be oligotrophic. While historically oligotrophic, the current status of Maine lakes is changing as a large number of lakes are now eutrophic due to the acceleration of the natural aging process by human activity (Davis et al. 1978; see China Lake Characteristics: Biological Perspective: Trophic Status). HISTORICAL PERSPECTIVE Regional Land Use Trends The historical land use trends in Maine reflect changing agricultural activity of the region. Prior to human settlement, Maine was nearly completely forested (Irland 1998). However, Colby College: China Lake Report 39 timber harvesting and settlement in the seventeenth, eighteenth, and nineteenth centuries dramatically changed the landscape of Maine. By 1872, forested areas of Maine had reached an all time low, only 53.2% of total land area (Plantinga et al. 1999). Since that point, agricultural activity and timber harvesting have declined in Maine, taking a sharp downward turn in the twentieth century. From 1950 to 1999, cropland area declined by 288,544 ha (713,000 acres), pasture land by 70,416 ha (174,000 acres), but forested area within Maine increased by nearly 162,000 ha (~400,000 acres) (Plantinga et al. 1999). The increase in forested area can be attributed to the decline in agricultural activity (Plantinga et al. 1999). Demographic shifts away from agriculture left former agricultural lands fallow and these lands have largely reverted to forest or are in the process of reversion. In contrast to the decline of agricultural land, municipal and residential lands in Maine increased in area during the twentieth century. Shifts toward town and urban centers and a new focus on tourism have led to an increase in human-based infrastructure for these land use types (City of Oakland 2005). The land use history of China and Vassalboro mirror historical regional trends within Maine and New England in general. Settlement of the China Lake region by European settlers began in 1760 in the Vassalboro area (Varney 1886). Initially a part of Sidney on the Kennebec River, Vassalboro was incorporated later in 1771. American soldiers from the Revolutionary War denied land bounties for their military services traveled north in search of land and squatted in the China/Vassalboro area (Grow 1975). Initially wilderness, the area was developed for human uses. Land was cleared, plowed, tilled, and leveled for agricultural and residential uses. Organized by Quakers in 1776 under the name of Harlem, China grew to be the fourth largest incorporated town in Maine by 1820 (Grow 1975). Incorporated after Vassalboro, the population of China soon exceeded that of its neighbor on the West Basin. The dramatic change in land use reflects the remarkable growth of China in this period. By the turn of the nineteenth century approximately 60% of forests in Kennebec County had been cut down (Grow 1975). Agriculture and industry continued through the nineteenth century, yet by the turn of the century these efforts began to decline when settlers began moving westward seeking more arable lands. The abandoned and fallow lands left behind began the process of succession into forest. Interestingly, in the same period, tourism emerged as an economic force in China, and greater attention was paid to recreating a pristine wilderness area to support the burgeoning industry (Manthey, pers. comm.). In the twentieth century, state, county, and local governments began Colby College: China Lake Report 40 regulating land use and restricting development. As a result, forested areas increased by approximately 250% between 1880 and 1995 in Kennebec County (Irland 1998). The changes in land use within the China Lake watershed match the predictable progression typical within Maine and New England. Initially pristine wilderness, land was largely deforested in the nineteenth century under the expansion of agricultural and industrial production. With the recession of these forces in Maine in the mid twentieth century, forested areas made significant resurgences. Currently, residential, commercial, and municipal developments represent the largest potential sources of land use change in the region. Water Quality Maine is home to more than 6,000 lakes (MDEP 2005b).