Topography and Land Cover:

The upland region is very flat (0-2% slope) and it comprises most of the watershed's land area. Land use in this region is dominated by agriculture, and cultivated fields cover 86% of the region. The second most expansive land cover, deciduous forest, makes up 6% of the total watershed area and is restricted predominantly to the riparian zones bordering the creek. This portion of the watershed is much steeper (40-60% slope). The remaining areas within the watershed are categorized as wetland, grassland, or farmstead.

Stream Gradient:

Seven Mile Creek is a small but very steep stream. On a 6.1 mile trip from its "headwaters" in the uplands down to its mouth at the Minnesota River, the creek drops 210 feet. This gives it a gradient of 34.4 feet/mile. For comparison, the Mississipi river drops less than 1000 vertical feet over its 2,350 mile journey to the Gulf of Mexico, a gradient less than 0.4 feet/mile. Gradient is an important factor in understanding flow velocity within a stream, which controls the stream's ability to erode banks, carry sediment, and incise a deeper channel.

Basic Geology:

The oldest rock outcropping in the park is Jordan sandstone, which forms the bluffs at the entrance to the park. This sandstone formation is overlain by glacial deposits from the most recent glaciation of this area (14-10,000 years ago). These glacial tills produced soils, which are characterized predominantly as poorly drained clay loams. Kasota stone, a decorative dolostone (part of the Oneota member of the Praire Du Chien Formation) mined across the river from immediately atop the Jordan, is not present in the park. It was eroded by rivers that incised the ravine within which the present-day Seven Mile Creek flows. Though SMC's path was originally cut by rivers well before the last ice age, the gouging out of the great Minnesota River valley by water released from glacial lake Agassiz is responsible for SMC's steep gradient. Over the last 10,000 SMC has been incising down through the Jordan in an attempt to find the shortest path to the lower-lying Minnesota River.

Climate:

Seven Mile Creek Watershed is continental, with cold dry winters and warm wet summers. Climatic records show an average monthly temperature of 46.2 F, and annual rainfall averages 28.91 inches per year. April to September is considered the growing season, and most rainfall is observed from April to July.

Click on the image to view average rainfall data for SMC Watershed