The Juneau Icefield Research Program has monitored outlet glaciers of the Juneau Icefield since 1946. On the west side of the ice field, the terminus of the Mendenhall Glacier, which flows into suburban Juneau, Alaska, has retreated . Of the nineteen glaciers of the Juneau Icefield, eighteen are retreating, and one, the Taku Glacier, is advancing. Eleven of the glaciers have retreated more than since 1948 — Antler Glacier, ; Gilkey Glacier, ; Norris Glacier, and Lemon Creek Glacier, . Taku Glacier has been advancing since at least 1890, when naturalist John Muir observed a large iceberg calving front. By 1948 the adjacent fjord had filled in, and the glacier no longer calved and was able to continue its advance. By 2005 the glacier was only from reaching Taku Point and blocking Taku Inlet. The advance of Taku Glacier averaged per year between 1988 and 2005. The mass balance was very positive for the 1946–88 period fueling the advance; however, since 1988 the mass balance has been slightly negative, which should in the future slow the advance of this mighty glacier.