Green Lake Integrated Phosphorus Management Plan and Alum Treatment Design

Since the 1990s, Herrera has monitored Green Lake and its watershed, developed the water and nutrient budgets, conducted diurnal studies of internal phosphorus loading, monitored the lake and educated the public on effects of an aluminum sulfate (alum) treatment, and prepared specifications for aquatic plant harvesting. In response to extensive toxic cyanobacteria blooms in the early 2000s, Herrera provided planning, permitting, engineering, and monitoring services to support a proposed alum treatment of Green Lake. This included a comprehensive study to determine the optimum approach to treating Green Lake with alum by evaluating historical data and relevant literature, and conducting tests to select the alum dose and develop treatment specifications and costs. Herrera provided technical oversight of engineering services, conducted all water quality monitoring during and after the 2004 alum treatment, prepared the treatment evaluation report. Herrera continued to provide expert limnological support services for Green Lake including collection and evaluation of sediment core data, development of a bioturbation model for predicting impacts of carp on internal loading of phosphorus, design and implementation of a stormwater monitoring program, aquatic plant evaluations, and pollutant source tracking. Because toxic cyanobacteria increased 10 years after the 2004 alum treatment, Herrera conducted statistical analysis of historical phytoplankton data collected since 1952 showing, recommended another alum treatment, and updated algae bloom monitoring and lake closure protocols. Herrera collected more sediment core data, prepared a plan for the third alum treatment in 2016, provided oversight, monitoring, and reporting of the 2016 treatment.