Amnicon-Dowling Lake Management District Aquatic Plant Management Planning Project

Project Dates

2012-2014

Introduction

The Amnicon-Dowling Lake Management District (ADLMD) has been active in protecting Amnicon and Dowling Lakes in Douglas County, WI developing its first Lake Management Plan in 1994. Since that time, additional projects have included water quality monitoring, revisions to the existing Lake Management Plan, and aquatic invasive species (AIS) education and prevention efforts. In the last few years, an over-abundance of aquatic plant growth in Amnicon Lake and a lack of aquatic plant growth in Dowling Lake has been the main issue of concern.

Project Area

Amnicon Lake is a 426-acre nutrient rich drainage lake located in west-central Douglas County, Wisconsin.  Amnicon Lake is relatively shallow with an average depth of 10 feet and a maximum depth of 31 feet. The shoreline of the lake is heavily developed. Amnicon Lake is a wild rice lake. The amount of rice is fairly modest, with a reported average harvest of 1.83 pounds. Recent years have seen a decline in the wild rice beds, another source of concern. Muskellunge and panfish are common in Amnicon Lake while largemouth bass and walleye considered present, but not abundant. Amnicon Lake has one public boat launch and a locally popular campground, Amnicon Acres. Water quality in Amnicon Lake has remained fairly steady over the last 20 years.

Adjacent and connected to Amnicon Lake is Dowling Lake. At 154 acres it is smaller and more shallow than it neighbor with an average depth of 7 feet and a maximum depth of 13 feet. It also has a highly developed shoreline. Dowling Lake is considered nutrient rich, but unlike Amnicon, its water quality was steadily deteriorating and the amount of aquatic vegetation steadily declined making way for algae dominated water. The fishery is similar to that of Amnicon Lake. There is one public boat launch on the lake.

Project Description

This project developed an Aquatic Plant Management Plan (APMP) for both lakes. Formal plant management planning had not been completed on either lake. Purple loosestrife and curly-leaf pondweed are two aquatic invasive species known to be present in system.  Curly-leaf pondweed is most prevalent in Amnicon Lake and appears to be encroaching on the wild rice beds. Purple loosestrife is abundant on both lakes, but biological control efforts over the last 15 years kept it from dominating the entire shoreline. Native aquatic plants were particularly dense in Amnicon Lake near its outlet to the Amnicon River. Lake access and navigation was severely restricted in this part of the lake causing substantial hardship to property owners. Dowling Lake had different issues. It appeared to have shifted from a plant dominated lake to an algae dominated lake. Vegetation was sparse and the water got very green during the summer and fall. Eurasian watermilfoil was not present in either lake, but the risk of introduction is high.

Project Goals

This project had three goals:

  1. Develop a better understanding of lake water quality and human influences on the Amnicon-Dowling system
  2. Identify, protect, and preserve the native species community within and around the lakes
  3. Develop an APMP for Amnicon and Dowling Lakes to guide future aquatic plant management efforts.

Aquatic Plant Management Plan

The overall goal of aquatic plant management in Amnicon and Dowling Lakes was to protect the lakes from degradation by preventing new invasions of non-native aquatic invasive species and through the containment and control of existing aquatic invasive species. A secondary goal was to improve access for property owners on Amnicon Lake whose ability to navigate to open water was impeded by dense aquatic plant growth. The primary objectives of this aquatic plant management plan were to support sustainable practices to protect, maintain and improve the native aquatic plant community, water quality, fishery, and the recreational and aesthetic values of the lakes; monitor for the introduction of new aquatic invasive species; and to contain and control existing AIS like curly-leaf pondweed.

An APMP defined different management alternatives and based on the data that is collected recommended the best alternatives to incorporate for a given body of water. An APMP was not intended to be a static document, but rather a tool that was used as a guide to make sound management decisions over the course of several years. As such, the management recommendations made in the document can be revised or updated if annual support data justifies it. Management results, public input, DNR counsel, and the best science of the day provided the necessary backdrop for the management recommendation made. An Implementation Matrix was provided to guide the ADLMD as it moved forward with management actions.

Upon completion of this project, the ADLMD sought additional financial support for implementation through WDNR grant programs, Lake District revenue, and donations from property owners on the two lakes.

Contact

Daniel Corbin
Chair
Amnicon-Dowling Lake Management District
715.399.2581
dandcorbin@gmail.com

Project Manager
Bruce Olson
715.720.6244
bolson@sehinc.com