Mackenzie River from the Peace-Athabasca system are significantly slowed by the delta area at the western end of Lake Athabasca causing the lake to rise, and the excess water can only flow out after the rivers have receded. The same phenomenon occurs at Great Slave Lake, which naturally regulates the flow from the Slave River into the Mackenzie. There are river gages at several upstream points along the Mackenzie River. The average flow rate at the outlet of Great Slave Lake is . At Fort Simpson, below the Liard River, it is . At Norman Wells it is , and at the
Lake Winnipesaukee called Acquadocton. Today, the site is called The Weirs, named for the weirs colonists discovered when first exploring the region. Winnipesaukee is a glacial lake but an unusual one, since the last glaciation actually reversed the flow of its waters. Draining the central portion of New Hampshire, it once flowed southeast, leaving via what is now Alton Bay toward the Atlantic Ocean. When glacial debris blocked this path, flow was redirected westward through Paugus Bay into the Winnipesaukee River. The latter flows west from the lake and joins the Pemigewasset River in Franklin to form the Merrimack River, which flows