FY 2023 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 monitoring will also provide data to identify physical influences that affect lake productivity (e.g. turbidity influence on euphotic zone depth). In 2024, QIN will also initiate an in-depth assessment of the Lake Quinault Fertilization Program – through the compilation and analysis of historic fisheries and limnology data before and during the lake fertilization period.

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 biomass.