FY 2020 Quinault Indian Nation Lake Quinault Nutrient Enrichment

The project includes the following elements: 1) fertilizer purchase and delivery; 2) fertilizing Lake Quinault with liquid nitrogen and phosphorus fertilizers; 3) monitoring of a suite of physical, biological, and water chemistry variables relevant to lake nutrient enrichment effectiveness monitoring (Ashley & Stockner 2003); 4) sample collection and processing; 5) data entry, data QA/QC, and database management; 6) data analysis and reporting; and 7) equipment maintenance/repair and operating expenses. The nutrient prescription is intended to enhance production of edible phytoplankton and zooplankton, the food source of sockeye fry, while avoiding the occurrence of nuisance algae responses. The fertilizer prescription will be developed in February then applied weekly by boat to surface waters of Lake Quinault from April to October using a blend of liquid fertilizer consisting of urea ammonium nitrate (UN 32) and ammonium polyphosphate (10-34-0). The limnology monitor is designed to measure sentinel variables that enable scientists to identify changes in the production cycles of the lake (Stockner 1981 and 1987; Shortreed and Stockner 1985) and chronicle changes in biomass and densities of major plankton components. Shifts in abundance of species and/or assemblages will signal changes in production, carbon flow, and the food web. The monitor will also provide data to identify physical influences that affect lake productivity (e.g. turbidity influence on euphotic zone depth).

The purpose of the project is to 1) supplement natural nutrient loads to Lake Quinault and 2) improve trophic level productivity and 3) increase Lake Quinault carrying capacity for juvenile sockeye salmon. Increased primary productivity is the most consistent measure of nutrient supplementation response in lakes. The prescribed nutrient load is equivalent to a yield of approximately 0.9 ug/L of chlorophyll a biomass. The project team will analyze and evaluate the data collected to identify seasonal productivity and report the trophic state of Lake Quinault.