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What is a Watershed?
A watershed is an area of land in which the surface water runoff drains to a specific point. In the case of Cornelius, water either drains to Lake Norman or Mountain Island Lake. There are three Watershed Protection Districts in Cornelius: Lake Norman Watershed Critical Area, Mountain Island Lake Watershed Protected Area, and Mountain Island Lake Watershed Protected Area 2. The districts are sensitive to the amount of impervious area in them, and the land in each of these districts is subject to protection regulations.
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Why do we have Watershed Protection Regulations?
By controlling the amount of water runoff that goes into Lake Norman and Mountain Island Lake, we protect our water supply. Pervious ground cover allows water to be filtered of pollutants by soil before entering the water supply. It is important that everyone follow the regulations in order to protect our water supply and the ecosystem for the future.
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What are the Watershed Protection Regulations?
The regulations for the Watershed Protection Overlay are set forth in Section 5.12 of the Land Development Code. For all three Watershed Protection Districts, there are three impervious cover options. The low impervious cover option for single family residential requires that all lots must be a minimum of half an acre. The low impervious cover option for all other residential and nonresidential development requires that the total built-upon or impervious area of a project must not exceed 24 percent of the project acreage. The high impervious cover option is for high-density development and must have engineered storm water controls to control runoff. This option may not be used in the General Residential zoning district in the Lake Norman Watershed Critical Area. The Town Board must approve the high impervious cover option.
For any lake front lot recorded using a high impervious cover option, a 100 foot undisturbed buffer from the 760 contour line is required. The 760 contour line is the elevation that is considered full pond for the lake. For low impervious cover options, a 50 foot undisturbed buffer from the 760 contour line is required for lake front lots. No trees larger than two inches in diameter can be removed from this buffer. Also, no permanent structure may be constructed in the buffer. This includes sheds, gazebos, sidewalks, and pools.
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Lake Norman Watershed Buffers
There is a 50 foot undisturbed buffer from the 760 contour line, or shoreline, of Lake Norman. The buffer is the natural undisturbed area of land adjacent to the lake that serves as water quality filter for storm water runoff. The buffer is 100’ in “high density” developments. A high density development which cannot be utilized in the General Residential district, exceeds either 2 units per acre or 24% built-upon area in which engineered storm water controls are used to control runoff and development may not exceed 50% built-upon area. Undisturbed means that trees and vegetation cannot be removed from the designated buffer area. It also means that with very few exceptions nothing can be built in this area (see below). Also, expanding existing structures is not permitted in the buffer. Prior to construction on lakefront property the buffer must be delineated and protected with silt fence.
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What is allowed in the 50’ buffer?
- Drainage should be designed to sheet flow across buffer; plunge pools, level spreaders, diversion devices, wetland flow should be used to provide sheet flow.
- Uses existing and on-going in the buffer prior to October 1, 1993.
- Removal of trees less than 2 inches in diameter, as measured 6 inches above the ground and all dead or diseased trees.
- Shoreline stabilization and dredging (upon approval of Duke Power 1-800-443-5193).
- Fences
- Pathways with pervious material underneath approved by Mecklenburg County Water Quality that meet the following regulations:
- Boardwalks with spaces at least 2 inches apart.
- Stepping stones no more than 3 feet wide with rock sections no larger than 225 square inches.
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What is not allowed in the 50’ buffer?
- Structures/built-upon area (houses, garages gazebos, outbuildings, roofs)
- Paved/gravel surfaces
- Septic drain systems or drain fields
- Repair areas
- New lawn/turf grasses
- Sediment basins/open channels/piped storm water
- Masonry walls
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Impervious Allowance
If you live on Lake Norman or in the Lake Norman Watershed (or Mountain Island Lake Watershed) then there is typically a maximum impervious allowance for your property. Impervious area is land that is built upon with a structure, surface, or roofed storage area that renders the land underneath impenetrable to water. (Wooden slatted decks and pool water areas are exempt). Generally, if you have a single-family residence then your allowed impervious amount will be approximately 24%.
Exceptions include properties in which a different impervious amount is specified on the recorded plat. Impervious restrictions do not apply to properties that were platted prior to October 1, 1993, or properties in which the plat denotes that property and every other property (on the plat) as being 20,000 sq. ft. or more of land.
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Are there any exceptions?
Here is a list of permissible exceptions:
- Uses that were existing and on-going in the buffer prior to October 1, 1993, including maintaining existing lawns with the following restrictions:
- Use may only be changed to an allowed use.
- Any use that has ceased for 1 year can not be reestablished.
- Removal of trees, upon approval of Mecklenburg County, that are less than 2 inches in diameter measured 6 inches above ground, and those that are dead or diseased.
- Shoreline stabilization and dredging with approval from Duke Power and Mecklenburg County Water Quality.
- Fences constructed without removing or damaging trees greater than 2 inch caliper.
- Water dependent structures and other structures such as flagpoles, signs and security lights.
- Pathways must be made from topsoil, mulch or sand or must be approved by Mecklenburg County Water Quality and meet the following requirements:
- Wooden Boardwalks
- Must have at least 2 inch spaces between boards.
- No trees can be damaged or removed during construction.
- Must not exceed impervious allowed for property (you can find you the impervious area for your property on the recorded plat).
- Stepping stones
- No more than 3 feet wide in any location.
- Rock sections no larger than 225 square inches.
- Spaces between rock sections must be at least 2 inches.
- The base material must be soil with only soil or vegetation between rock sections.
- Should be designed around trees and sloped to divert water from the lake.
- No trees can be damaged or removed during construction.
- Must not exceed impervious allowed for property.
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