It might not be so obvious that the size of a lot has anything to do with water pollution. However, lot size dictates how many lots will border a river, stream, or lake. Each developed lot in some way or another can contribute to bank eriosion, polluted runoff, and loss of wildlife habitat. The impact accumulates lot by lot and can, in time, become too much for the biological community to take. If more lots are developed than what the body of water can support, it will suffer.
Impervious Surfaces, which cannot be penetrated by water, are a key part of the equation. Research around the country has shown that when more than 10% of a watershed is covered by impervious surfaces, water quality declines.
Water tends to move much faster over roofs, decks, and driveways than over naturally vegetated areas. As water moves faster, its ability to erode or carry sediment increases dramatically. When its speed doubles, water will move particles 64 times larger, transport 32 times more material in suspension, and produce four times more erosive power.
Impervious surfaces allow sand, gasoline, oils, antifreeze, salts, and other chemicals to be carried quickly to surface waters. If natural vegetation were in place, many of these chemicals would be broken down.
Habitat Fragmentation occurs when natural shoreline vegetation is removed and replaced with urban-style lawns. Many species of north woods wildlife cannot survive in a fragmented habitat. Research in Northern Wisconsin has documented the changes in amphibian and bird populations as shorelines become increasingly fragmented. Green frogs disappear. Warblers, thrushes, and vireos are replaced with grackles and cowbirds.
Exotic Species are those introduced from other areas and are not native to the landscape. Many species of plants found along developed shorelines were introduced either on purpose or accidentally by people.
Great amounts of time and money are then spent managing them - to get them to grow (bluegrass lawns) or to eliminate them (weeds). In any case, the fertilizers, pesticides, and herbicides used often end up in our lakes and streams harming water quality or local wildlife.
Exotic species such as house cats, English sparrows, European starlings, purple loosestrife, and others can eliminate the native species through predation, competition and disease.