Order Soma Online The Lake Washington Improvement Association’s goal is to maintain and improve the water quality in Lake Washington. Water quality testing is completed April through September and are conducted to monitor total phosphorus (nutrient needed for plant growth), Chlorophyll-A (measures amount of algae in the water), Secchi disk (measures water clarity) and Trophic state index (measure overall nutrient enrichment, or average of phosphorus, chlorophyll-A and secchi depth).