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Publication Date

1989

Keywords

Water quality--Minnesota; Watershed ecology

Abstract

ABSTRACT-Surface water quality in southeastern Minnesota's driftless area exhibits subregional and local spatial patterns which are highly correlated with subsurface geology and land-use practices. Some variables appear to respond on subregional or watershed scales. Nitrate, specific conductance, alkalinity, and surface water atrazine concentrations were lower in streams originating from the Prairie Du Chien or Jordan sandstone ~quifers of easte:n Fillmore and Houston Counties than those originating from the Galena limestone aquifer m west-central Fillmore County. In addition, the numbers of pollution intolerant and functionally specialized invertebrates in the benthic community were higher in the eastern streams. Gross primary production on tile substrates, transported organic matter, and atrazine concentrations were highest in an agricultural watershed and lowest in a forested watershed. Other variables are more responsive to local influences such as riparian land-use. Substrate median particle size, macrophyte composition on riffies, diversity of benthic invertebrates, and number of invertebrate predators were highest on riffies adjacent to forested riparian zones. Stream temperature and turbidity were higher at riffie sites adjacent to open agricultural riparian zones. Our resul~s demonstrate spatial patterns in southeastern Minnesota water quality which are strongly correlated with subsurface geology and land-use practices. These patterns exist on different spatial scales (i.e., local, wate_rs~ed, ~ubregio~al) within the driftless area ecoregion. Effective monitoring and management of water quality m this ecoreg1on must consider a finer spatial scale than that suggested by the aquatic ecoregion approach.

First Page

6

Last Page

13

Included in

Geology Commons

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