Home | Legislative Bodies | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | Collin County Engineering 825 N Mcdonald St Mckinney, TX 75069 Phone : (972) 548-3727 Collin County Justice Of Peace 200 S Mcdonald St Mckinney, TX 75069 Phone : (972) 424-1460 Llano Water Plant 203 W Haynie St Llano, TX 78643 Phone : (325) 247-3359 Collin County Agriculture Service 825 N Mcdonald St # 150 Mckinney, TX 75069 Phone : (972) 548-4233 Collin County Constable 200 S Mcdonald St Mckinney, TX 75069 Phone : (972) 548-4419 Human Resources 210 S Mcdonald St # 612 Mckinney, TX 75069 Phone : (972) 548-4606 County 4-h & Youth 825 N Mcdonald St # 150 Mckinney, TX 75069 Phone : (972) 548-4232 Pottsboro Sewer Department Rr 2 Pottsboro, TX 75076 Phone : (903) 786-3806 Collin County 199th District 210 S Mcdonald St # 222 Mckinney, TX 75069 Phone : (972) 548-4415 Collin County Adm Service 210 S Mcdonald St Mckinney, TX 75069 Phone : (972) 548-4601