The Big Fork River watershed is one of 39 watershed units designated by the Minnesota Department of Natural Resources for evaluation of the State 's water resources. Included is an appraisal of the occurrence, quantity, quality, and availability of ground and surface waters. Water resources are not intensively developed anywhere in the watershed. Most development is in the southern half, as much of the northern half is peat-covered wetlands. Essentially all water used is withdrawn from ground-water sources, mainly glacial drift, which ranges from 0 to 250 feet in thickness. Most ground water is of the calcium or sodium bicarbonated type. The degree of mineralization increases down-gradient in the flow system. Groundwater is typically very hard and high in iron and manganese. Lakes and large areas of wetlands have a natural regulating effect on streamflow. Water in streams is of the calcium bicarbonate type. The amount of mineralization at a given time reflects surficial geology, being greatest in streams draining till areas and least in streams draining peatlands. Water drained from peatlands is commonly higher in color and iron and lower in pH than water from areas of mineral soil.
