Michigan Basin Regional Ground Water Flow Discharge to Three Great Lakes

Abstract

Ground water discharge to the Great Lakes around the Lower Peninsula of Michigan is primarily from recharge in riparian basins and proximal upland areas that are especially important to the northern half of the Lake Michigan shoreline. A steady-state finite-difference model was developed to simulate ground water flow in four regional aquifers in Michigan's Lower Peninsula: the Glaciofluvial, Saginaw, Parma-Bayport, and Marshall aquifers interlayered with the Till/"red beds," Saginaw, and Michigan confining units, respectively. The model domain was laterally bound by a continuous specified-head boundary, formed from lakes Michigan, Huron, St. Clair, and Erie, with the St. Clair and Detroit River connecting channels. The model was developed to quantify regional ground water flow in the aquifer systems using independently determined recharge estimates. According to the flow model, local stream stages and discharges account for 95% of the overall model water budget; only 50% enters the lakes directly from the ground water system. Direct ground water discharge to the Great Lakes' shorelines was calculated at 36 m3/sec, accounting for 5% of the overall model water budget. Lowland areas contribute far less ground water discharge to the Great Lakes than upland areas. The model indicates that Saginaw Bay receives only approximately 1.13 m3/sec ground water; the southern half of the Lake Michigan shoreline receives only approximately 2.83 m3/sec. In contrast, the northern half of the Lake Michigan shoreline receives more than 17 m3/sec from upland areas.

Impacts of Pleistocene glaciation on large-scale groundwater flow and salinity in the Michigan Basin

“…Topographic highs, such as glacial moraines, serve as major recharge areas, while shallow groundwater discharges into surface drainages in topographic lows and eventually out to the Great Lakes. These results are consistent with previous reports of modern groundwater flow in the basin from hydraulic head measurements, MODFLOW modeling, and age tracer studies (Vugrinovich 1986; Mandle & Westjohn 1989; Hoaglund et al. 2002; McIntosh & Walter 2006).…”

“…It was assumed that the hydraulic conductivities of the Precambrian basement rocks underlying the sedimentary package were low enough that flow is minimal, therefore the bottom of the model and the right hand side of the model where Paleozoic sediments onlap onto the Canadian Shield were set as no flow boundaries. The left‐hand side of the model corresponds to the center of the basin and a natural hydrologic divide, where regional groundwater discharges in the Saginaw Lowlands to the Great Lakes (Vugrinovich 1989; Hoaglund et al. 2002) (Fig.…”

Data‐Driven Approach for Analyzing Hydrogeology and Groundwater Quality Across Multiple Scales

“…Hoaglund et al () used numerical models to show that, at present conditions, modern lake elevation in Saginaw Bay is exceeded by the head in the underlying Marshall aquifer by as much as 21 m, creating a significant potential for upward flow. Others studying the general basin‐scale groundwater processes noted that the Michigan Lowlands and Saginaw Lowlands represent two major regional discharge zones, (e.g., Westjohn and Weaver ; Westjohn et al ; Hoaglund et al ). The findings of the site‐specific geochemical studies, coupled with knowledge of the basin‐scale hydrogeology, suggest that the upwelling of brines systematically impacts the near‐surface environment and its water resources in the Lower Peninsula of Michigan.…”

Environmental analysis of groundwater in Mecosta County, Michigan

“…Indeed, 76.4 billion gallons of groundwater are being withdrawn daily, with agricultural irrigation accounting for almost 75% of that total (Maupin and Barber 2005). Even in the Great Lakes basin, where almost 90% of the United States' surface fresh water is located, groundwater is critical for the basin's hydrology and ecological health (Baker et al 2003;Hoaglund et al 2002). Although quantity is critical to maintain flows and water levels, groundwater quality also is threatened due to changing land uses.…”

“…However, groundwater is the primary source of drinking water for approximately 8.2 million people within the watershed (Grannemann et al 2000) and serves as an important water supply for industrial, agricultural, and domestic needs. Although direct groundwater flow to the Great Lakes' nearshore region is limited (Hoaglund et al 2002), groundwater accounts for approximately 79% of the streamflow that ultimately reaches Lake Michigan (Holtschlag and Nicholas 1998) and can profoundly influence the hydrology and ecology of wetlands (Hunt et al 1996).…”