North and South Twin Lakes suffer from poor growth and high mortality of stocked salmonids.  As a result of five years of study it was determined that the primary problem was that trout were limited to a narrow band of water during summer stratification because water temperatures in the epilimnion were too high and the hypolimnion was anoxic.  In 2008 a hypolimnetic oxygenation system was installed in North Twin and operated briefly.  In 2009 and 2010 the oxygenation system was operated from mid May to Mid October.  Dissolved oxygen levels in the hypolimnion were kept between 5mg/l and 7mg/l.  Fish movements were monitored in both North Twin (oxygenated) and South Twin (unoxygenated as a control) throughout the summer by acoustic tracking, hydroacoustics and gill nets.  Fish were found to utilize the hypolimnion in North Twin but not in South Twin.

In 2010 a hypolimnetic oxygenation system was constructed and installed in South Twin Lake and briefly tested.  In 2011 oxygen will be injected into the hypolimnion of both North and South Twin Lakes from May to October.  Oxygen levels will be monitored and flow rates adjusted accordingly.  Fish growth, mortality and condition factor will also be tracked.  One of the primary goals of 2011 will be to assess the effects of hypolimnetic oxygenation on the salmonid fishery of both North and South Twin Lakes in order to determine long term goals and plans for both lakes.