Pilar Deniston

Senior Project Advisor

Angela Strecker

Document Type

Project

Publication Date

Spring 2024

Keywords

lake, phosphorus, fertilizer, ban, land cover

Abstract

Freshwater lakes are essential ecosystems, providing crucial services for humans, plants, and animals. However, eutrophication, a process driven by an excess of nutrients such as phosphorus, poses a significant threat to lake health and water quality. To mitigate excess phosphorus and eutrophication, many states, including Washington, have implemented bans on phosphorus-containing fertilizers. This study evaluates the efficacy of Washington State's 2013 phosphorus-containing fertilizer ban, focusing on 58 lakes in western Washington. This study organized, filtered, and analyzed data from multiple counties' monitoring programs to examine total phosphorus concentrations before and after the ban. Additionally, this study involved a land cover analysis in assessing the relationship between land use changes and phosphorus concentrations.

The results of this study revealed a variety of outcomes. While there was no significant overall reduction in phosphorus concentrations across all lakes, analysis at the county level revealed significant decreases in Snohomish County post-ban. The results showed that while there is a negative relationship between land cover changes and phosphorus concentrations, it is not significant, suggesting other factors may influence total phosphorus concentration. These findings underscore the complex interplay of environmental factors in shaping lake nutrient dynamics. While the phosphorus-containing fertilizer ban has shown promise in some areas, its effectiveness varies across regions and requires further investigation. Future research should explore additional factors like public awareness campaigns, septic systems, and land use effects that influence lake phosphorus concentrations and should consider broader implications for freshwater ecosystem management.

Department

Environmental Sciences

Type

Text

Rights

Copying of this document in whole or in part is allowable only for scholarly purposes. It is understood, however, that any copying or publication of this document for commercial purposes, or for financial gain, shall not be allowed without the author’s written permission.

Language

English

Format

application/pdf

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