Add MaintainScrollPositionOnPostback="true" to your page directive.
<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="PaymentScheduleByAgency.aspx.cs" Inherits="BBCApplication.Staff.PaymentScheduleByAgency" MasterPageFile="~/Site2.Master" MaintainScrollPositionOnPostback="true"%>
This will keep your page to the scrolled position after postback.