Å·ÃÀ¿Ú±¬ÊÓƵ

Lagerman Reservoir is a saline water body subject to changing hydrologic regime, periodic algal blooms, and subsequent fish kills. Inflow has decreased and the water level is constantly below the spillway, rendering this system a closed, evaporite basin. The objective of this study is to survey the ecological condition of the reservoir to obtain scientific data for future management decisions and insure the safety of its recreational visitors. Weekly shore samples and monthly depth profile samples were taken, along with data synthesis of the EPA’s CyAN satellite monitoring system. Extreme conditions were observed both chemically and ecologically. Cation and anion concentrations were high, with a pH of 8 or higher. Dissolved oxygen was very low, indicating unfavorable conditions for fish and macroinvertebrates. Transparency and nutrient concentrations were also low, with nitrogen limiting the system. The algal biomass was dominated by colonies of Synechococcus, a cyanobacteria typical of marine habitats with a potential to produce toxins and fix nitrogen. In addition, Dolichospermum, Lyngby, Oscillatoria, and Merismopedia are potential toxin producers found in the reservoir. Chlorophyll-a and phaeophytin analysis indicated similar trends to the CyAN satellite data, with a peak of algal growth around mid-June/early July, followed by a die off of algal biomass. Based on Carlson’s Trophic State Index, this reservoir ranged from eutrophic to hypereutrophic from June to August 2020. Lagerman Reservoir is considered to be unsuitable for fish and vulnerable to toxic algal blooms that could be hazardous to human health.