Leaf Pollution Update

The LQEC has been researching nutrient pollution – the addition of excess nitrogen and phosphorus to the lake ecosystem resulting in excess algae production and harmful algal blooms (for example, bluegreen algae). There are several significant sources of nutrient pollution:

1. Lawn Fertilization

3. Leaves recommendations also included when to use quick-release versus water-insoluble (WIN) nitrogen products.

Lawn fertilization practices significantly impact the health of the lake. In 2008 the Environmental Protection Agency reported that fully 40 to 60 percent of lawn fertilizer ends up in surface or groundwater and subsequently in waterways. While agricultural operations are not common around Lake Sherwood, where present these can contribute significantly to water pollution also. Forty percent of the nutrient pollution in Chesapeake Bay comes from fertilizer and manure.

The management of waterfowl is problematic. Lake Sherwood provides excellent habitat for resident as well as overwintering waterfowl, especially Canada geese.

The Soil Sampling Project final draft and recommendations are currently under review by the LQEC before general dissemination to the membership. At this stage, it would be premature to release the final report but one important point stands out and is worth mentioning. Every study, research paper and article regarding lawn fertilization reviewed by the committee began any lawn fertilization program with a soil test to determine what nutrients were needed. Follow up soil testing periodically to monitor the status of nutrients was also recommended. Soil testing is inexpensive. Testing is important to make adjustments to the nutrient mixture being applied based on need and not on estimation.

Applying only the nutrients needed is particularly critical for lakefront lawns as excess nutrients easily enter the lake and contribute to nutrient pollution. Excess phosphorus is highly problematic as one pound of phosphorus stimulates 500 pounds of vegetation growth. In our lake this means 500 pounds of algae! The final report will be released to all members along with the fertilization recommendations. Future activity for this project also will involve the LQEC meeting with lawn care vendors and interested DIY lawn care members to discuss fertilization practices that are cost effective while producing both a healthy lawn and a healthy lake.

Their feces whether deposited directly into the lake or on lakefront yards contribute to the nutrient loading. The management of waterfowl has been mentioned by the LQEC over the last few years but remains complicated. Future updates will discuss management options.

This update on nutrient pollution relates to leaf pollution. When Lake Sherwood was completed and homes were constructed there were specific covenants that required different types of trees. Chief among these was a requirement for a pin oak on each lot. For several decades the residential areas around the lake and in the drainage basin had only small- to medium-sized trees. The amount of leaf drop in the fall did not seem to be a significant problem. However, trees mature. The residential areas are now populated with mature trees that produce a tremendous number of dropped leaves in the fall.

During the latter part of September through early December large quantities of dead leaves accumulate on the lawns and streets as well as in the gutters and storm drains/culverts in the basin. Great effort is expended by continued on page 8