CHAPTER 6 - A Citizen's Manual for Developing Integrated Aquatic Vegetation Management Plans

IDENTIFY WATER BODY/WATERSHED FEATURES (STEP D) 

A lake or river is a dynamic, living system, teeming with all sorts of physical, chemical and biological activity. The system extends beyond its shores to include surrounding land whose waters drain into the water body (the watershed). A water body and its watershed are inseparable. In fact, water body conditions are very much influenced by what occurs in the watershed.

For instance, a watershed contributes nutrients to a water body that are necessary for aquatic plant growth. These nutrients—especially phosphorus and nitrogen—flow to the lake from all parts of the watershed by way of streams, ground water, and stormwater runoff. In addition, activities in the watershed, such as agriculture and forestry, road maintenance and construction can all contribute silt, debris, chemicals, and other pollutants to the water body. These potential sources of contaminants are examples of nonpoint pollutant sources. Nonpoint sources arise from more widespread, dispersed sources, in contrast to point sources such as pipes or outfalls that dump directly into the water body.

A Plan should consider these possible sources of nutrient inputs and identify long-term measures to reduce them. Controlling watershed inputs from these sources can potentially enhance the effectiveness of primary in-lake control measures.

Because of these important land-water connections, integrated aquatic-plant management has to take a look at the entire picture. A water body can’t be managed without understanding what makes the whole system tick. Learning about the features of both the watershed and water body aids in understanding problems in the water body and in designing an effective management program.

How To Describe The Watershed And Water Body

This planning step is composed of two tasks:

This step is really a fact-finding endeavor, which is conducted by the steering committee. The committee may have already uncovered some of the background information recommended below in its preliminary search for data (See Getting Started, Chapter 1).

1. Describe the watershed: To understand a water body’s problem, you first need to identify features of the watershed. It is important to note characteristics of the watershed such as:

• Size and boundaries of the watershed
• Tributaries, wetlands and sensitive areas
• Land use activities in the watershed
• Nonpoint pollutant sources
• Existing watershed management, monitoring or enhancement programs
• The presence of rare, endangered or sensitive animals and plants

Much of this information is readily available as documents, maps or data that can be obtained from local planning or public works departments and state agencies. Appendix C --Watershed and Limnological Background Information offers a more detailed discussion on these topics and how and where to collect information on your watershed.

Most of the watershed information can be presented pictorially in a watershed snapshot. The following illustration depicts such a snapshot showing unique features of a hypothetical watershed. 

2. Describe the water body: You probably know more about your lake than just about anyone else. You can probably easily describe your lake in general terms; you know where the weeds are thickest, where the snags are that can snap your prop or tangle your fishing line, and where the big, hungry fish like to hang out. The description of your lake that is required for a Plan is really no different from how you would describe your lake to a friend. However, where your description to a friend might include observations and information on how to avoid obstacles and where to catch fish, the observations required for a Plan describe what it is about the water body that can affect the growth of plants. Understanding the factors that influence weed growth is an important step in controlling a nuisance weed situation.

Water body features that are important to identify are:

• location
• Size, shape, and depth
• Water sources
• Physical and chemical characteristics (water quality)
• Biological characteristics (animals and plants)
• Shoreline uses
• Outlet control and water rights.

Because our state has such diverse climates, ranging from inland desert to coastal plains to high elevation mountain areas, the location of your water body within the state can explain unique aspects of the problem and what might work best in your situation. The size, shape and depth of a water body determines where aquatic plants can grow, and other biological and chemical processes occurring in the waters. A water body is influenced by types and quantity of inflowing and outflowing water sources. In addition, understanding water quality characteristics, such as temperature, light, dissolved oxygen levels and nutrient concentrations in the water, helps explain the overall health and limitations of the system. Finally, there are important cultural factors on the shoreline (land use, regulating flow through the outlet) that further define the water body. These physical, chemical, and biological features of freshwater ecosystems are described in more detail in Appendix C-Watershed and Limnological Background Information. 

Getting Started In Your Search Of The Water Body

Many lakes in Washington have been mapped by the U.S. Geological Survey and the Department of Ecology. The results were published in Reconnaissance Data on Lakes in Washington and Data on Selected Lakes in Washington. The information in these surveys may be out of date, especially with respect to land use, but they can provide much of the basic background information required for planning. 

Sampling/Monitoring To Fill Data Gaps

Some of the information you need to describe your water body and develop a Plan may not be available. In that case, an organized information gathering program might be necessary to fill in background data gaps. The information can be collected by lake-area residents. Special sampling equipment is often necessary to obtain some information.  

Also, certain types of water samples require analyses by approved analytical or biological laboratories. See A Citizen's Guide to Understanding and Monitoring Lakes and Streams, Volunteer Lake Monitoring: A Methods Manual, or The Lake and Reservoir Restoration Guidance Manual for descriptions of sampling methods and equipment.

Ecology's Citizen Lakes Monitoring Program or local monitoring programs may be sources of training and assistance in setting up a sampling program for your water body. Examples of small-scale monitoring projects on the local level are King County/METRO's small lakes program, Snohomish County's volunteer lake monitoring program, Pierce County Cooperative Extension Office's program for stream monitoring, and local Adopt-A-Stream programs. 

• Appendix C-Watershed and Limnological Background Information
• Reconnaissance Data on Lakes in Washington²⁸
• Data on Selected Lakes in Washington²⁹
• The Lake and Reservoir Restoration Guidance Manual⁴
• Ecology's Citizen Monitoring Project^E
• Volunteer Lake Monitoring: A Methods Manual⁹
• A Citizen's Guide to Understanding and Monitoring Lakes and Streams⁶
• Limnology²³
• Ecology staff
• Local governments
• Freshwater limnologists/chemists

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