How to Protect Your Lake: A Homeowner's Guide

Every lakefront property owner has a direct impact on their lake's water quality. The choices you make about your shoreline, lawn, septic system, and stormwater management collectively determine whether your lake improves or declines over the years. Across our dataset, 1,768 lakes show improving trends and 1,349 are declining, the actions of shoreline property owners are the single biggest factor in which direction a lake goes.

1. Restore and Maintain Your Shoreline Buffer

The most impactful thing any lakefront property owner can do is maintain a buffer of native vegetation between their lawn and the water. A shoreline buffer is a strip of native grasses, wildflowers, shrubs, and trees - ideally at least 25 to 50 feet deep, that acts as a living filter for everything flowing from your property toward the lake.

Research from the University of Minnesota and Wisconsin DNR demonstrates that well-established buffers remove 50% to 90% of sediment, 50% to 85% of nitrogen, and 30% to 60% of phosphorus from surface runoff. The root systems of native plants absorb dissolved nutrients, while the dense vegetation physically traps sediment particles before they reach the water. Buffers also stabilize shoreline soil against wave erosion, provide nesting habitat for ducks, songbirds, and pollinators, and shade the nearshore water to inhibit algae growth.

Starting a buffer does not require eliminating your entire lakeside lawn. Even a 10-foot strip of native plants provides measurable benefits. Many county Soil and Water Conservation Districts offer free native plant design assistance and subsidized native plant sales in spring. Minnesota's Buffer Law requires a 50-foot average buffer on public waters, but voluntary buffers on private lakefront often exceed this because property owners see the results in clearer water and better fishing.

2. Eliminate Phosphorus from Your Property

Phosphorus is the nutrient that drives algae growth in virtually every lake in Minnesota and Wisconsin. Every pound of phosphorus that enters a lake can produce 300 to 500 pounds of algae. The most common sources from residential lakefront properties are lawn fertilizer, failing septic systems, exposed soil from construction or landscaping, and pet waste left on the ground.

Both Minnesota and Wisconsin ban the use of phosphorus-containing lawn fertilizer except when establishing new lawns or when a soil test confirms a phosphorus deficiency. However, compliance is inconsistent, and many lakefront homeowners inadvertently apply phosphorus by using all-purpose fertilizers. Always check the three numbers on the fertilizer bag, the middle number is phosphorus, and it should be zero for lakeside use. Better yet, most established lawns in the Upper Midwest do not need any fertilizer, native grasses and low-maintenance lawn mixes thrive without supplemental nutrients.

Leaf litter is another significant phosphorus source that many homeowners overlook. A single mature oak tree drops leaves containing 1 to 2 pounds of phosphorus each fall. When those leaves blow or wash into the lake, the phosphorus is released as they decompose. Raking or mulching leaves that accumulate near the shoreline, rather than allowing them to enter the lake, can meaningfully reduce nutrient loading.

3. Maintain Your Septic System

Lakeside septic systems that are failing, undersized, or improperly sited can deliver substantial phosphorus loads directly to the lake through groundwater. The Minnesota Pollution Control Agency estimates that 10% to 30% of septic systems near lakes are nonconforming. A single failing system can release 5 to 10 times more phosphorus than a properly functioning one.

Have your system inspected every three years (required in Minnesota shoreland zones) and pumped every two to three years. Watch for warning signs of failure: slow drains, sewage odors near the drainfield, unusually green grass over the drainfield area, or surfacing sewage. If your system was installed before 1990, it may not meet current setback and sizing standards, consider a voluntary upgrade, especially if your lake's grade is C or below. Many lake improvement districts and watershed districts offer low-interest loans for septic upgrades, recognizing the significant water quality return on investment.

4. Manage Stormwater on Your Property

Every hard surface on your property, roof, driveway, patio, compacted path, converts rainfall into runoff that flows toward the lake carrying pollutants. A single inch of rain on a 2,000-square-foot roof generates 1,250 gallons of runoff. If that water flows directly to the lake across lawn or bare soil, it carries phosphorus, sediment, and other contaminants with it.

Simple stormwater management practices can dramatically reduce the pollutant load reaching your lake. Redirect downspouts away from the lake toward rain gardens, shallow, planted depressions designed to capture and infiltrate roof runoff. Use permeable materials for paths, patios, and driveways where possible. Minimize the total amount of impervious surface on your property. Maintain a thick, healthy ground cover (lawn, native plants, or mulch) on all exposed soil to prevent erosion. These practices are inexpensive, low-maintenance, and cumulatively effective, when a majority of shoreline property owners manage their stormwater, the lake responds with improved clarity and reduced algae.

5. Prevent Aquatic Invasive Species

Aquatic invasive species like zebra mussels and Eurasian watermilfoil can permanently alter a lake's ecosystem, and prevention is far more effective than any available treatment. Minnesota law requires boaters to remove all plants, drain all water, and dispose of unwanted bait before leaving any water body. Wisconsin has similar requirements.

As a lakefront property owner, you can help by educating guests and renters about invasive species prevention, supporting your lake association's boat inspection programs, reporting any suspected new infestations to your state DNR, and participating in volunteer monitoring programs like Starry Trek (for starry stonewort) and AIS Detector. Early detection of a new infestation gives managers the best chance of containment, once established, most aquatic invasives cannot be eradicated.

6. Get Involved in Lake Management

Individual property owner actions matter, but coordinated watershed-scale management produces the greatest results. Join your lake association, or help start one if none exists. Lake associations organize volunteer monitoring, coordinate shoreline buffer projects, advocate for effective septic system enforcement, and pursue grant funding for watershed management.

Consider supporting or establishing a lake improvement district (LID), which has taxing authority to fund professional lake management work including water quality monitoring, alum treatments for internal phosphorus loading, aquatic invasive species management, and watershed conservation practices. Minnesota and Wisconsin both provide enabling legislation for LIDs, and dozens of lakes in each state have used this model to fund sustained restoration efforts.

Frequently Asked Questions