Hydrology, water quality, and restoration potential for the Upper Big Darby Creek, Central Ohio

Ohio Journal of Science, The, June, 2005 by Li Zhang, William J. Mitsch, Daniel F. Fink

ABSTRACT. The restoration of riparian buffers as well as the creation and restoration of wetlands along streams are practices that can be used to control point and non-point source pollution. Our study provides hydrology and water quality data from 2000-2002 in anticipation of recommending restoration of the headwaters of the Big Darby Creek Watershed in central Ohio. One tributary of concern in the headwaters, Flat Branch, contributed 11% of the total river flow during April 2002 flooding and 56 and 88% of the flow in the headwater study area during non-growing (winter and early spring) and growing (summer and early fall) seasons, respectively. There were significant differences in water chemistry, both temporally and spatially, at each sampling station within the upper watershed. Flat Branch was seasonally or continuously higher in temperature, pH, and turbidity, and lower in dissolved ions and oxygen than Darby Creek. Low dissolved oxygen at dawn during the summer months caused by diurnal metabolism in the water column is also a concern in Darby Creek. We propose the creation/restoration of riparian wetlands at the confluence of the Big Darby and Flat Branch as one solution to degrading water quality in the upper Big Darby watershed. Flood pulses, particularly from the Flat Branch, could be directed to riparian wetlands, which would minimize downstream erosion and capture the water exactly when several pollutants (sediments, nitrates, and so forth) are in higher concentrations. The restoration area could have flood control, habitat, and ecotourism values as well.

OHIO J SCI 105(3):46-56, 2005

INTRODUCTION

Riparian forests and wetlands enhance stream ecosystems and their water quality (Odum 1981; Naiman and Decamp 1997; Ward 1998; Mitsch and Gosselink 2000; Sweeney and others 2002; Mitsch and Jorgensen 2004). Restoration of riparian buffers and wetlands along streams stabilize stream channel morphology in addition to controlling non-point source pollution coming from the landscape. They also provide refuge for a great variety of wildlife and some fish species associated with the streams and rivers. If overbank flooding occurs from the stream and river into the riparian forests and wetlands, sediments can be deposited on the floodplain from the river while particulate organic matter can be exported to support detrital food chains in the stream.

A number of research projects around the world have shown how the functions gained from riparian restoration can benefit both nature and humans (Kadlec and Hey 1994; Jacks and others 1994; Moustafa 1999; Nairn and Mitsch 2000; Spieles and Mitsch 2000; Hoagland and others 2001; Mitsch and others 2001, 2002; Henry and others 2002). Peterjohn and Correll (1984) and Lowrance and others (1984) demonstrated that riparian forests of coastal plain agricultural watersheds can be nutrient sinks that buffer the nutrient discharge from surrounding agroecosystems. They also showed that nutrient uptake and removal by soil and vegetation in the riparian ecosystem prevented agricultural upland outputs from reaching stream channels. Most recently, Mitsch and Jorgensen (2004) concluded from a review of many studies that, because chemical and biological conditions will respond accordingly if the proper hydrologic conditions are developed, riparian restoration can lead to both short- and long-term water quality benefits. However, there are still very few techniques to assess the viability of riparian restoration to an entire watershed. Successful stream restoration depends not only on understanding the physical and biological processes that influence ecosystems at the watershed scale, but also in the proximity of the restoration effort to the sources of disturbance (Goodwin and others 1997; Tein and others 1999; Ward and others 1999; Poudevigne and others 2002; Mitsch and Jorgensen 2004).

Our study investigates the potential of restoring the headwaters of the Big Darby Creek Watershed in central Ohio. Big Darby Creek is a stream of relatively high water quality and biological diversity, but recent upstream developments (industrial and agricultural) have raised concerns about pollution effects downstream. Properties adjacent to the creek in the upstream reaches were purchased by the Ohio Chapter of The Nature Conservancy in the 1990s and early 2000s, leading to discussions on the restoration of stream channels, wetlands, and/or riparian ecosystems in this watershed to improve water quality, ameliorate flood peaks, provide habitat, and improve/maintain the biological character of the creek. Any such project would need both pre- and post-restoration monitoring to determine the effectiveness of the restoration. The creation of any wetland/riparian system would require complete data on stream hydrology for example. Because the ability of wetlands to trap or transform nutrients generally increases as the water retention time increases, our study emphasizes understanding the hydrology and water chemistry dynamics temporally and spatially within the upper watershed network. The main goal of this study is to assess the quality of the streams in the vicinity of the potential restoration sites and to provide assistance on the siting and design of riparian restoration in the study area.