Eagan's Water Resources Program is responsible for restoring, protecting, and enhancing Eagan's lakes, ponds, and wetlands. The City stewards more than 1,200 bodies of water across it's 33 square mile area, including a portion of the Lower Minnesota River Watershed.

Our Water Quality & Wetland Management Plan guides the City's efforts to protect and improve these critical community assets.  The most recent plan covers efforts from 2018 through 2027.  In addition to water quality management efforts, Eagan's Water Resources Program is also responsible for protecting and improving fishing and recreational opportunities in the City.  You can read more about our specific efforts by clicking the links below.

General Information


Below are some of the most frequently used terms in the world of water quality!

Microscopic plants in water or attached to rocks and other materials. Algae are the food base of most aquatic animals. We estimate algae abundance by measuring how much chlorophyll a is in the water. Excessive amounts of algae can degrade water quality by reducing transparency or by lowering dissolved oxygen during decay.

(Aluminum sulfate): A liquid chemical the City uses to control phosphorus in water resources. Alum removes phosphorus from lake water and binds phosphorus in the sediment. It also can remove phosphorus from stormwater before it flows into lakes.

Aquatic animals without internal skeletal structures, such as insects, mollusks, and crayfish.

Specialized bacteria that may produce toxins that are harmful to people or pets. There's no easy way to know if toxins exist without analyses of water samples. The safest precaution is to avoid any contact with surface waters that are stagnant or blue-green.

Green pigment in plants that is necessary for photosynthesis. To estimate algae abundance, we measure the amount of chlorophyll a as a weight per volume of water (milligrams per liter) or as parts per million. Chlorophyll a is a common reference of water quality.

(Potamogeton crispus): Non-native, aquatic plant that most likely came to Minnesota in early 1900s from Europe. Curlyleaf pondweed has spread to many Minnesota lakes via boats, trailers, and equipment. Generally the first pondweed growing in spring, it can interfere with recreation by producing dense mats at the surface. It is a prohibited invasive species in Minnesota.

Oxygen in water produced by plants and mixed from air. Dissolved oxygen is vital for fish and other aquatic animals. We measure the amount as a weight per volume of water (milligrams per liter) or as parts per million. In winter, dissolved oxygen in lakes can be low when ice and snow blocks sunlight and air contact with the water. When below 5 parts per million, sensitive fish have an increased risk of death.

Total land area draining runoff to a surface water.

Natural process by which organic sediment and nutrients accumulate in lakes and wetlands, increasing excessive growth of algae and macrophytes. Urbanization accelerates eutrophication when lakes and wetlands are connected to the stormwater drainage system.

Algae that start growing on the bottom of ponds. They reproduce and join into strands that float to form surface mats. The plant's slimy, cottony texture becomes a quick nuisance. Foul odors emit when the algae bleach and die.

Exterior coverings (i.e., roofs, driveways, sidewalks, and streets) that restrict rainwater and snowmelt from soaking into the ground. Impervious surfaces cause stormwater to run off into the stormwater drainage system.

Multi-celled plants that grow in or near water. Macrophytes generally are beneficial by producing oxygen and providing habitat for aquatic animals. Excessive amounts can exist where water is shallow and with high phosphorus levels.

Measure of relative acidity based on strength of hydrogen reactivity, within a scale from 1 (most acidic) to 14 (most alkaline). A pH of 7 is neutral. Our lakes have pH levels ranging from 7.0 to 9.5.

Key nutrient influencing algae and aquatic plant growth. Phosphorus is abundant in tree litter, yard debris, pet waste, soils, etc. Runoff transports the phosphorus to our lakes. We measure the amount of phosphorus as a weight per volume of water (micrograms per liter) or as parts per billion. Total phosphorus is a common reference of water quality.

Process by which green plants convert sunlight into usable energy for animals. Photosynthesis is essential to the food base and dissolved oxygen in lakes.

Process by which animals convert organic material into energy. Respiration uses oxygen and releases carbon dioxide. When aquatic bacteria decompose organic matter, respiration lowers dissolved oxygen in lakes.

See Stormwater.

Flat round device that measures transparency. We use a Secchi disk to determine how deep into a lake we can see (feet or meters). About 30 volunteers use Secchi disks for our citizen lake monitoring program. Father Pietro Angelo Secchi, a 19th century astronomer, invented the device and first used it in the Mediterranean Sea in 1865.

Accumulated organic and inorganic material on the bottom of lakes and wetlands. Sediment includes decayed algae and plants, animals, minerals, soil, etc.

Rainwater and snowmelt that run off impervious surfaces rather than soak into the ground. Stormwater drains into and through a system of street catch basins and underground pipes. This transports nutrients, suspended solids, fine soils, plant debris, drippings from vehicles, and other substances from drainage basins.

Algae, fine soil particles, etc. that float in water or that stormwater transports. We measure the amount of suspended solids as a weight per volume of water (milligrams per liter) or as parts per million. Suspended solids is a common reference of water quality.

Extent to which lake water is clear, indicating amount of light penetration. We measure transparency by determining how deep into a lake we can see a Secchi disk (feet or meters). Transparency is a common reference of water quality.

See Drainage basin.

According to Minnesota law, wetlands are where all of the following exist: 1) soils that developed in wet or moist conditions, 2) water at or near the surface, and 3) vegetation that grows in wet or very moist conditions.

Water Regulations

Legal support for our Water Resources programs includes the following sections of City Code. You can also access the entire online City Code.