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1. Watershed Management A watershed is an area of land that water flows across, through, or under on its way to a common point in a stream, river, lake, or ocean. Watersheds not only include water bodies such as streams and lakes, but also all the surrounding lands that contribute water to the system as runoff during and after rainfall events. The relationship between the quality and quantity of water affects the function and health of a watershed. Thus, significant water removals (such as irrigation) or water additions (such as permitted discharges) are important. Watersheds can be extremely large, covering many thousands of acres, and often are subdivided into smaller subwatersheds for the purposes of study and management. WATERSHEDS AND WATER QUALITY To effectively address water issues, it is important to examine all natural processes and human activities occurring in a watershed that may affect water quality and quantity. Runoff that eventually makes it to a water body begins as surface or subsurface water flow from rainfall on agricultural, urban, residential, industrial, and undeveloped areas. This water can carry pollutants washed from the surrounding landscape. In addition, wastewater from various sources containing pollutants may be released directly into a water body. To better enable identification and management, potential contaminants are classified based on their origin as either point source or nonpoint source pollution. Point source pollution is discharged from a defined location, such as a pipe, ditch, or drain. It includes any pollution that may be traced back to a single point of origin. Point source pollution is typically discharged directly into a waterway and often contributes flow across all stream conditions, from low flow to high flow. In Texas, dischargers holding a permit through the Texas Pollutant Discharge Elimination System (TPDES – see Appendix A for a complete list of acronyms) are considered point sources, and effluent is permitted with specific pollutant limits to reduce the impact on the receiving waterbody. Nonpoint source pollution (NPS), on the other hand, comes from a source that does not have a single point of origin. The pollutants are generally carried off the land by runoff from storm water following rainfall events. As runoff moves over the land, it can pick up both natural and human-related pollutants, depositing them into water bodies such as creeks, rivers, and lakes. Ultimately, the types and amounts of pollutants entering a water body will determine the quality of water it contains and whether it is suitable for particular uses such as irrigation, fishing, swimming, or drinking. Page 1 Watershed Management BENEFITS OF A WATERSHED APPROACH State and federal water resource management and environmental protection agencies have embraced the watershed approach for managing water quality. The watershed approach involves assessing sources and causes of impairments at the watershed level and utilizing this information to develop and implement watershed management plans. Watersheds are determined by the landscape and not political borders, and thus often cross municipal, county, and state boundaries. By using a watershed perspective, all potential sources of pollution entering a waterway can be better identified and evaluated. Just as important, all stakeholders in the watershed can be involved in the process. A watershed stakeholder is anyone who lives, works, or engages in recreation in the watershed. They have a direct interest in the quality of the watershed and will be affected by planned efforts to address water quality issues. Individuals, groups, and organizations within a watershed can and should become involved as stakeholders. Stakeholder involvement is critical for selecting, designing, and implementing management measures to successfully improve water quality. WATERSHED PROTECTION PLANNING The United States Environmental Protection Agency (EPA) developed a list of nine key elements (see Appendix B) which serve as guidance for development of successful watershed protection plans (WPP). Using that guidance, plans are developed by local stakeholders with the primary goal being to restore and/or protect the water quality and designated uses of a water body through voluntary, non-regulatory water resource management. Public participation is critical throughout plan development and implementation, as ultimate success of any WPP depends on stewardship of the land and water resources by landowners, businesses, elected officials, and residents of the watershed. The Lavon Lake WPP defines a strategy and identifies opportunities for stakeholders across the watershed to work together and as individuals to implement voluntary practices and programs that restore and protect water quality. Page 2 2. Overview of the Watershed GEOGRAPHY Lavon Lake is the uppermost reservoir on the East Fork of the Trinity River and provides drinking water to over 1.6 million residents in North Texas (Fig. 2.1). The 769-squre-mile watershed (492,095 acres) lies within the larger Trinity River Basin and includes parts of Collin, Fannin, Grayson, and Hunt Counties (Fig. 2.2). Elevations within the watershed range from 901 feet in the upper reaches of the East Fork of the Trinity River subwatershed in Grayson County to the conservation pool elevation of 492 feet in Lavon Lake. Incorporated areas within the watershed include twenty-seven towns and cities (Table 2.1). Notable tributaries to the lake include the East Fork of the Trinity River, Indian Creek, Pilot Grove Creek, Sister Grove Creek, and Wilson Creek, which are described in greater detail below. There are also a number of smaller, ephemeral streams which flow into Lavon Lake which include Elm Creek, Price Creek, Ticky Creek, and White Rock Creek. The East Fork of the Trinity River above Lavon Lake The headwaters of the East Fork of the Trinity River rise in Grayson County approximately 1.5 miles north-northwest of Dorchester, TX and flow south south-southeast for approximately 50 miles before draining into the western arm of Lavon Lake. Honey Creek is the primary tributary to the East Fork of the Trinity River above Lavon Lake. Honey Creek rises approximately 2.5 miles south-southeast of Gunter, TX and flows south-southeast for 21 miles before its confluence with the East Fork of the Trinity River approximately 0.6 miles southeast of the intersection of SH-75 and FM-543 near McKinney. Elevations in the East Fork of the Trinity River subwatershed range from 901 feet to the conservation pool of 492 feet in Lavon Lake. The East Fork of the Trinity River subwatershed drains approximately 136,958 acres (Table 2.2). Indian Creek Indian Creek rises in Trenton, TX in Fannin County and flows south for approximately 16 miles before its confluence with Arnold Creek, approximately 4.25 miles southeast of Blue Ridge, TX. Indian Creek then continues southwest for approximately 8 miles before draining into Pilot Grove Creek less than 2 miles upstream of its confluence with Lavon Lake. The headwaters of Arnold Creek rise approximately 3 miles south of Leonard and flow for 13 miles before joining Indian Creek. Another major tributary to Indian Creek is Bear Creek, which rises approximately 3 miles west of Leonard, TX and flows south for approximately 14 miles before joining Indian Creek 1 mile upstream of the confluence point of Indian and Arnold Creeks. Page 3 Overview of the Watershed Pilot Grove Creek The headwaters of Pilot Grove Creek rise approximately 2 miles east of Tom Bean, TX and flow south for 36 miles before draining into the eastern arm of Lavon Lake. The Pilot Grove Creek subwatershed is relatively long and narrow. Thus, save for the aforementioned Indian Creek subwatershed, there are no major tributaries to Pilot Grove Creek. Sister Grove Creek The west and east prongs of Sister Grove Creek rise 1 mile and 4 miles east of Howe, TX, respectively. These two prongs join approximately 3 miles east of Van Alstyne, TX to form the main stem of Sister Grove Creek. The creek then flows south for 29 miles before draining into the eastern arm of Lavon Lake. Wilson Creek The headwaters of Wilson Creek rise in Collin County approximately 2 miles east of Celina, TX and flow southeast for 29 miles until its confluence with the western arm of Lavon Lake. Wilson Creek flows through the heart of McKinney, TX and is by far the most urbanized of the Lavon Lake subwatersheds. Figure 2.1. The East Fork of the Trinity River flowing through a rural portion of the watershed. Page 4 Overview of the Watershed Table 2.1. Incorporated areas in the Lavon Lake watershed. Name BOC 2015 County Receiving % of City Limit in Population Estimate Subwatersheds1 Lavon Watershed2 Allen 98,143 Collin Wilson Creek; Other 16.1% Anna 11, 463 Collin East Fk Trinity River; 100% Sister Grove Creek; Pilot Grove Creek Blue Ridge 850 Collin Pilot Grove Creek; 100% Indian Creek Celina 7,697 Collin Wilson Creek 9.2% Dorchester 89 Grayson East Fk Trinity River 73.6% Fairview 8,438 Collin Wilson Creek 99.9% Farmersville 3,447 Collin Elm Creek; Other 92% Frisco 154,407 Collin Wilson Creek 0.2% Gunter 1,394 Grayson East Fk Trinity River 40.8% Howe 2,798 Grayson East Fk Trinity River; 28.8% Sister Grove Creek Lavon 2,889 Collin Other 8.8% Leonard 1,970 Fannin Indian Creek 97.3% Lowry 1,780 Collin East Fk Trinity River 100% Crossing Lucas 6,883 Collin Wilson Creek; White 70.8% Rock Creek; Other McKinney 162,898 Collin Wilson Creek; East 81% Fk Trinity River Melissa 7,436 Collin East Fk Trinity River; 100% Sister Grove Creek Nevada 1,008 Collin Other 9.9% New Hope 639 Collin East Fk Trinity River 100% Princeton 8,939 Collin Sister Grove Creek; 100% Ticky Creek; Other Prosper 15,967 Collin Wilson Creek 30% St. Paul 1,132 Collin Other 60.3% Tom Bean 1,055 Grayson Sister Grove Creek; 42.8% Pilot Grove Creek Trenton 628 Fannin Indian Creek 78.2% Van Alstyne 3,344 Grayson East Fk Trinity River; 100% Sister Grove Creek Weston 334 Collin East Fk Trinity River 100% Whitewright 1,633 Grayson Pilot Grove Creek NA3 Wylie 46,708 Collin Other 49.6%4 1 Other includes unnamed tributaries and areas that drain directly to Lavon Lake.

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