Chapter 2: Watershed Science Overview Purpose This chapter overviews the science of watershed, including the geographic scale, water cycle, ecosystem dynamics, and water pollution from a nonpoint source. This chapter is designed to be an educational resource for understanding how watersheds work and how a watershed is affected by land use. Chapter Acknowledgements This chapter was prepared using material from The Outlet/Lye Creek Watershed Action Plan and by the watershed coordinator and BRWP partners.

What is a Watershed? A watershed is any area of land where surface water drains into a common body of water, such as a river, lake, or wetland. If water from a certain area drains into a particular body of water, then that certain area shares a common watershed. A watershed can contain one or more of the following features: streams, ditches, ponds, lakes, and/or wetlands. A watershed is also known as a “drainage basin” and/or Figure 2.1: Watershed diagram “hydrological unit.” The Riley Creek map (See map 2.1, pg. 2-2) shows the location of the watershed within the larger Blanchard River Watershed. The Blanchard River Watershed covers area in six counties. The Blanchard River Watershed is located within the larger Maumee River Basin which is a part of the Western Lake Erie Basin. The Blanchard River Watershed is identified using an 8-digit Hydrological Unit Code (HUC), 04100008. There are six subwatersheds located within the Blanchard River Watershed. Each of these subwatersheds is identified using an 10-digit HUC. The Riley Creek subwatershed’s HUC is 0410000804. There are 5 smaller 12-digit HUC subwatersheds located in The Riley Creek subwatershed. Map 2.2 (See pg. 2-3) shows the 12-digit subwatersheds. The Blanchard River Watershed is also a part of the Western Lake Erie Basin (WLEB). The Blanchard River flows into the Auglaize River, which flows into the Maumee River in Defiance. The Maumee River flows into Lake Erie in Toledo. Because the Blanchard River flows into Lake Erie it is subjected to the rules and regulation pertaining to Lake Erie. Chapter 3 will explain which rules and regulations apply to Lake Erie and the Blanchard River. Map 2.3 (see pg. 2-4) shows the location of the Blanchard River Watershed in the WLEB. Riley Creek watershed Action Plan

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Map 2.1: The Riley Creek Watershed location within the Blanchard River Basin and Ohio

Blanchard River Watershed

Riley Creek Watershed

ODNR Coastal Management

Riley Creek watershed Action Plan

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Map 2.2: 12-Digit Watersheds in Riley Creek Watershed

ODNR Coastal Management

12-digit subwatersheds located within the Riley Creek watershed (HUC 041000804) 041000080401 - Binkley Ditch-Little Riley Creek 041000080402 - Upper Riley Creek 041000080403 - Marsh Run-Little Riley Creek 041000080404 - Middle Riley Creek 041000080405 - Lower Riley Creek

Riley Creek watershed Action Plan

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The US EPA and ODNR began to require the use of the USGS’s new Hydrological Unit Code system in 2010 on all watershed action plans and grants. Under this new system, HUCs have changed from 11 and 14-digits to 10 and 12digits for identifying watersheds below the 8-digit level. Table 2.1 shows the changes as they apply to the Riley Creek watershed.

Map 2.3: Location of Blanchard River Watershed in theWestern Lake Erie Basin

Riley Creek watershed Action Plan

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Hydrologic (Water) Cycle All the water on Earth is stored in three reservoirs: surface water (streams, lakes, oceans, and glaciers), underground (groundwater), and atmosphere (clouds). Basically, water travels through these reservoirs by a process known as the water cycle. Water that falls from the sky may become run-off, infiltrate into the ground, or evaporate/transpire back into the atmosphere, depending on the conditions of the area. Once water has returned to the atmosphere, it has completed the process, and the cycle starts again. Water is essential to the weather patterns and climate system of the Earth. As water circulates through the process, weather conditions are distributed throughout the Earth, which in turn creates various landscapes and ecosystems. The Great Lakes naturally maintain their water quantity through the inflows (precipitation and run-off) and outflows (evaporation and discharge to the Atlantic Ocean) as part of the global water cycle. The Great Lakes become the “battle ground” for air masses bringing warm moist air up from the Gulf of Mexico and running into cold dry air masses from the Arctic area. As a result, the phrase “wait a day, the weather will change” applies to the Great Lakes region.

Figure 2.2: Water Cycle Riley Creek watershed Action Plan

http://www.epa.gov/watertrain/ecology/s7.jpg 2-5

Watershed Ecology Understanding the structure and processes of watersheds helps us better recognize the effects of human activities on water quality, habitat, plant and animal communities, and the quality of human life. Watershed dynamics can be separated into three categories: chemical budgets, water budgets, and biotic structure. In a healthy watershed, all three factors are in balance. Riparian zones have a variety of definitions; however, they generally refer to an area of vegetation, usually woody species, that acts as a transition from the water’s edge to the adjacent land. A healthy, natural riparian zone, often referred as a “buffer,” provides the essential functions to filter excess nutrients (chemical budget) from entering the stream and to store flood waters (water budget) that could have negative impacts on aquatic and terrestrial life native to the watershed. In our local watersheds, losses of riparian buffer and non-point source pollution are the greatest stressors impacting streams. Figure 2.4 on page 2-7 shows the benefits of various vegetation zones for pollution reduction and maintaining stream health.

Figure 2.3: Watershed ecology diagram demonstrating modes of movement of water and chemical factors and their relation to the biotic structure. redrafted from Johnson and Van Hook, 1989. Analysis of biogeochemical cycling processes in Walker Branch Watershed

Riley Creek watershed Action Plan

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Riley Creek Watershed Action Plan

Figure 2.4: Example of a forested riparian buffer and benefit for various vegetation zones for pollution reduction and maintaining stream health.