Thread: What the Wier!

I was reading the 178 page master plan for Truman lake and found this:
"A submerged rock weir (skimming weir) is present at Harry S. Truman to prevent low dissolved oxygen (D.O.) in hydropower releases during peak stratification periods during summer months. “Skimming weirs” function as an underwater dam which create an impermeable wall to prevent release of low D.O. water from below the thermocline (Figure 4). They have been very successful at Kansas City District hydropower lakes, although all both projects report decrease in temperature and dissolved oxygen of releases when thermocline elevation exceeds the top of the weir. During the flood year of 2019, Truman Lake surface elevation exceeded the multipurpose pool elevation by 34 feet. Consequently, thermocline elevation measured during monthly water quality profiles, exceeded the crest of the skimming weir from June-September with peak 20 feet above the weir in June (Figure 5). During the worst case of low dissolved oxygen release during June 2019, approximately 51% of the water volume flowing over the skimming weir during 60,000 CFS flood release was composed water from the bottom layer. The minimum dissolved oxygen measured below Truman Dam (site HT-1a) in flood year 2019 was 6.4 mg/L in September while temperature measured below Truman Dam from the mixing zone (site HT-1A at fishing access pier) was 1.3°C lower than surface value measured at site HT-1 between skimming weir and dam."