The Kettle River Watershed Phosphorus Reduction Project


This project is a partnership between Carlton, Pine, Kanabec, and Aitkin Soil & Water Conservation Districts (SWCD), with the Carlton SWCD acting as the project administrator.   Certain landowners in these counties received a letter because their properties lay within the priority area for reducing phosphorus pollution in the Kettle River Watershed. We are working with landowners in the priority areas on conservation projects to reduce the amount of phosphorus entering the Kettle River Watershed.  Reducing sediment and nutrient pollution to the Kettle River will protect water quality within the watershed and will also benefit the St. Croix River, a State Wild and Scenic River and designated canoe route.  The Kettle River even hosts a slowly growing lake sturgeon population, conservation of this ancient species will be dependent on maintaining clean water.

The priority conservation area was determined by using the Environmental Benefits Index tool, which identified the highest potential for phosphorus.  For areas that the EBI tool was unavailable, land use and proximity to surface water were the key components for prioritization.

Phosphorus Transport: Linking Land and Water

Land use and development certainly can have a profound impact on the quality of water in lakes, rivers and streams, as well as to our drinking water. A primary impact from land use is the increased contribution of phosphorus through surface water runoff. Impervious and cultivated surfaces such as fields, lawns, roads, driveways, and buildings increase the rate and volume of surface water flows. When attached to soil particles, phosphorus is carried into a lake or stream by the water runoff from land.

Phosphorus is a general soil nutrient that when in excess in a water feature, can cause severe algal blooms and oxygen depletion leading to degradation of water quality and diminished aesthetic and recreational enjoyment. The greater the phosphorus content of runoff water, the more the water quality in the receiving water is threatened. Phosphorus is critical because it is usually the nutrient defining lake water quality in Minnesota.

In order to get a general idea of the water quality impacts from various types of land use, federal and state agencies created a metric called the Land Use Export Coefficients. The coefficient is an assigned phosphorus runoff figure to each type of land use and was determined from years of monitoring and research. Using these formulas, coefficients can be used to estimate the phosphorus runoff for a watershed where the areas of specific contributing land use are known.

The change in predicted phosphorus loading is striking as land use changes from a natural setting type – wooded or wetlands – to developed land uses such as cultivated or urban uses. Note in the chart, cultivated land has about twice the amount of phosphorus runoff as grassland and small lot residential has eight to nine times the amount of forestland. Therefore, as land use changes from natural vegetated systems to cultivated and built environments, runoff increases and thus the capacity for the water to carry more pollutants, whether in solution or as sediment, also increases. (Source: Sustainable Lakes Planning Workbook. Minnesota Lakes Association)

The U.S. Environmental Protection Agency (EPA) and the Minnesota Pollution Control Agency (MPCA) use phosphorus runoff coefficients to estimate the changes in the quality of runoff likely to follow land use changes. Forested land covers, for example, are estimated to produce 0.13 pounds of phosphorus per acre per year whereas igure cultivated land is 0.89 pounds per acre per year and for shoreland residential type land covers it is 1.12 pounds per acre per year.
Land UseTotal Phosphorus Runoff
Shoreland Residential1.12
Urban Residential1.12
Forest land0.13

Ways to Decrease the Phosphorus

Conservation practices helpful to this effort focus on slowing the flow of runoff and protecting stream banks and lakeshores from erosion.  Land along lake and stream shorelines can benefit from planting buffer strips of trees, shrubs or native vegetation. Old septic systems can be updated to stop leaking, rain gardens can filter out lawn fertilizer and road pollutants, forests can be planted with a stewardship plan to reduce the cost of woodland ownership, and livestock can be provided off-stream watering systems to reduce erosion.

The following are the targeted methods to reduce the phosphorus input or Best Management Practices (BMPs) that landowners in the priority areas have available to them to address the loading on their property.  In addition, the SWCD can provide separate project plans such as tree planting and wildlife habitat improvement. Cost share for materials, labor and project oversight services may also be available.  Funding is available until the targeted funds have been used or through December 2014.

Rain Gardens

Rain Gardens are depressed landscape areas of perennial flowers and other native plants designed to capture runoff from roofs and streets.  Planted near impermeable surfaces such as driveways, streets, and compacted soils, a rain garden mimics the pollutant removal and water absorption of a natural forest or meadow by allowing natural infiltration (filtering water through the soil).

Runoff sediments, fertilizers, pesticides and other harmful chemicals increase as development replaces forested and agricultural lands because impermeable surfaces do not allow for settling or infiltration.

Instead of letting storm water flow fast and unfiltered, directly into lakes and streams, rain gardens filter pollutants and slow water flow, lessening flood potential, while reducing erosion and runoff into lakes and streams. Because the gardens typically only require 6-8 inches of digging, and utilize local vegetation, rain gardens are inexpensive to implement and low-tech for easy maintenance.


Rain Barrel

A Rain Barrel is any type of container used to catch water flowing from a downspout and store it for later use. Rain naturally contains pollutants, including phosphorus and mercury. When these pollutants flow over impermeable surfaces like roofs and other hard surfaces, they are much more likely to enter lakes and streams, where they can become a detriment to water quality. Diverting rainwater off roofs and into rain barrels, allows rain water to be used later for watering plants, so that it can infiltrate naturally into the soil instead polluting lakes and streams. The rainwater captured is also naturally “soft,” oxygenated and devoid of minerals, chlorine and other chemicals found in treated water, making it ideal for watering plants. For set-up, a rain barrel is simply placed under a shortened existing down spout, and can have a spigot attached to the end for watering flower gardens, lawns and house plants. It’s a natural way to fertilize, and conserves groundwater use, reducing peak water demands during summer months. During winter months, barrels can be taken out of operation by simply turning them upside down.

Fun fact: For every inch of rain that falls on just one square foot of your roof, you can collect just over a half gallon of rainwater (0.6 gallons).


Forested Riparian Buffers

Forested riparian buffers are plantings of trees, shrubs and grasses designed primarily for water quality and wildlife habitat purposes.  Planted along rivers, streams, lakes and some wetlands, riparian buffers help to prevent pollutants from reaching surface waters.  Establishing trees, shrubs and grasses in the zone adjacent to streams or creeks can sustain or enhance water quality and wildlife habitat.

The Kettle River and surrounding watershed is home to hundreds of trout and sturgeon.  Sturgeon, a cold water species, are sensitive to warm stream temperatures and pollution.  Planting trees and other plants in the riparian buffer prevents phosphorus and other runoff pollution from entering streams by slowing overland water flow, increasing soil infiltration, and providing structures like roots for soil stabilization. Trees also shade streams, decreasing direct sunlight, which could warm the stream.  As a result, water remains cleaner and temperatures stay lower with less fluctuation during the day, compared to the non-shaded areas of the stream. Without buffers to trap runoff, stream sediment levels can hinder trout and sturgeon spawning, and may clog the gills of these fish, which demand high levels of oxygen. Additionally, trees also provide woody debris for the stream, another important component of trout habitat.

Depending on the landowner’s objectives, plant materials in the buffer can also be selected to provide food, shelter and nesting areas for various wildlife species. Wider buffers are needed to enhance wildlife habitat for species like the golden-winged warbler and sharp-tailed grouse, while narrow buffers may provide a travel corridor.


Lakeshore Buffers

A Lakeshore buffer is a planting of trees, shrubs, grasses and wildflowers designed for water quality and wildlife habitat purposes. Lakeshore buffers help to prevent pollutants like soil and phosphorus from reaching surface waters by slowing overland water flow to prevent nutrient runoff, erosion and sedimentation. These vegetative shoreline buffers can stop 85% of sediment runoff and phosphorus pollution from entering lakes and streams. Buffers also provide a sheltered aquatic habitat for fish, and dragonfly nymphs, while also attracting ducks, songbirds and butterflies on land. Lakeshore buffers can also stop traffic from nuisance animals on lawns, like burrowing muskrats and Canada geese.

Buffer zones extending 25-50 ft are preferable, but zones of 10-15 ft still provide some benefits. Lakeshore restorations provide habitats for fish and turtles as well as attract birds and insects to the area. Lakeshore restorations not only help the environment, but also add to a property’s scenic beauty and privacy. Best of all, they are low-maintenance. Because buffers utilize native vegetation, there is no need for mowing, trimming, pruning or watering.


Tree Plantings

Tree Establishment aims to plant trees as a means to reduce erosion and restore native vegetation cover for habitat restoration and protection, erosion control and flood control. Trees provide food, shelter and nesting areas for various wildlife species and serve as a barrier for sun and wind.

Depending on objectives, landowners may choose different plants and areas for tree planting. Trees reduce soil and storm water runoff into streams, decreasing phosphorus pollution and erosion. In winter, trees can control drifting snow and protect livestock from cold and wind. In springtime, tree cover spreads the snow melt over a longer period, reducing runoff and peak stream flows capable of flooding. Plantings may also enhance habitats for species like sharp-tailed grouse and golden-winged warbler, or they may simply provide a travel corridor for migration. Landowners may also choose to establish a harvestable plot, allowing for some economic opportunities as well.


Forest Stewardship Plan

A Forest Management Plan is a specific kind of woodland management plan prepared by a natural resource professional, available to landowners with 20 or more wooded acres. Landowners with forest stewardship plans that are more than 10 years old are encouraged to update their plans with a qualified natural resource professional. The plan provides technical advice and long-range forest management planning to interested landowners. A qualified natural resource professional will meet with you, conduct a field inventory, assess specific land factors and complete the plan. Plans are designed to meet your goals while maintaining the sustainable natural capacity of the land and are registered with the DNR.

The plan provides a comprehensive overview of your land including an aerial photo, a map of the timber types and plant communities.  The plan outlines your goals, the resources on your land and recommends management options such as:

  • Planting trees
  • Building trails
  • Enhancing habitat
  • Thinning and release cutting
  • Harvesting timber

Landowners with a forest management plan may also be eligible for some programs such as wildlife habitat improvement or soil erosion control, as well as cost-share and tax reduction programs.


Fertilizing Management Plans

Fertilizing management plans supply landowners the information necessary to provide adequate fertilizer for their crops, without polluting water sources. Nutrients not utilized by crops may leach into groundwater via runoff or agricultural drainage systems, reducing water quality.

By creating a fertilizer management plan based on crop history, expected yield, and soil testing, farmers can reduce the amount of fertilizer applied to fields, decreasing runoff into lakes and streams. Applying more nutrients than recommended can be expensive, and have harmful environmental consequences. On average, farmers participating in fertilizer management plans have been able to cut fertilizer by 25% without affecting crop yields, saving an average of $16/acre. Applying blended fertilizers allows farmers to match an exact fertilizer blend to a soil test recommendation, reducing any excess not needed by the crops. Furthermore, applying these blends in split applications reduces fertilizer loss due to runoff and leaching into the soil. In the US, 50% of fertilizer applied on single-application is never taken up by plants due to the combination of over-fertilizing in a single period, and applying standard grade fertilizers that may be too rich in nitrogen, potassium or phosphorus.

Fertilizing management plans also allow optimize plant growth through pH control, as over-fertilizing affects soil pH. Soils with low pH (acidic, < 7) cannot support the bacteria that break down organic material, resulting in nutrients being sequestered in the organic material, unable to be used by crops. High soil pH (alkaline, > 7) affects solubility of iron, magnesium, zinc and copper, and also speeds conversion of soil-bound ammonium to nitrate, which is much more susceptible to leaching, and constitutes the bulk of nitrogen lost to leaching. Ideally, a pH of 6 to 7 (pH 7 = neutral) allows for the most availability of plant nutrients. Most mineral soils have a pH ranging from 5.5–7.5.

Livestock Management

Off-stream watering and livestock exclusion fencing keep livestock away from streams, reducing or eliminating the time that livestock spend in or near streams, while providing a cleaner, alternative source of drinking water. However, because of the abundant water resource, livestock may remain in this area too long, resulting in phosphorus pollution from urine and manure deposition in or near streams. Grazing and soil compaction also keep vegetation sparse in these areas, meaning that runoff can easily carry phosphorus-laden sediments into the river, further increasing phosphorus pollution. By controlling livestock access to streams, and providing them with an alternate water source, livestock avoid riparian areas. Livestock avoidance can lower phosphorus pollution in streams by 80%, while also enhancing stream bank stability and decreasing soil compaction, which can hinder plant establishment on stream banks. Off-stream watering also provides cleaner water, promoting healthier and more productive livestock.

Above: Cattle use frost-free nose-powered water pumps.
Above: Cattle use frost-free nose-powered water pumps.

This Project is a Partnership with: