resource protection guidelines
The resource-protection objectives are designed to ensure the quality and quantity of the water resources, as well as to protect cultural, historical and recreational resources. As individual properties, situations and organizations vary, the numbers and percentages cited below are not absolute. Each government will determine its own objective-satisfying performance standards. Objective A:
Protect and improve base flows and stream habitat through recharge. Protect Cockeysville Marble recharge areas from contamination.
Base flows affect the availability of drinking water and the diversity of stream species. Local governments can limit new impervious surfaces, particularly in areas of Cockeysville Marble; encourage wetland preservation; encourage the maintenance and upgrading of stormwater management structures; and support low-impact development techniques that preserve natural features.
- Establish stormwater infiltration performance standards to minimize increases in stormwater runoff volume due to development. Discourage design standards requiring excessive impervious surfaces in development. Encourage the preservation of existing wetlands, and where appropriate, the creation of artificial wetlands and the use of infiltration trenches and swales.
- Limit impervious surfaces to 10% in residential areas and 20% in commercial/industrial areas where recharge areas of the Cockeysville Marble formation occur. Greater impervious surface may be acceptable only where soil permeability is already low, or where infiltration techniques allowing groundwater discharge are used.
- Outside the Cockeysville Marble area, limit impervious surfaces to less than 10% in rural areas, less than 35% in suburban areas, and less than 50% in commercial/industrial and high-density areas. In all cases, the use of retention and recharge techniques should be encouraged if not required.
- Encourage the maintenance of stormwater management structures and the retrofitting of extant structures that are inadequately designed; investigate the development of a stormwater management public utility as a means of doing this.
- Encourage and support the use of low-impact development techniques, including cluster development approaches, to facilitate on-site recharge through the use of existing natural-resource features.
Protect and improve water quality and stream habitat through floodplain and wetland protection.
Excessive nutrients (including nitrogen and phosphorus) and excessive sediments (soil particles) are pollutants particularly detrimental to streams and rivers and to the plants, animals and fish that depend on them for survival. High levels of nutrients in a stream cause increased algal growth and a subsequent reduction in dissolved oxygen. Many kinds of fish that normally thrive in streams cannot tolerate low oxygen levels.
A large volume of sediment damages a stream system by suffocating fish and aquatic insects and by filling crevices between rocks where fish and invertebrates live and hide. Suspended sediment clouds otherwise clear stream water, occluding sunlight and limiting the growth of aquatic plants.
Wetlands and floodplains filter the water flowing in streams and the groundwater entering them. Sediments are filtered and nutrients are absorbed and transformed, providing substantial benefits to downstream users. This filtering improves the quality of downstream drinking-water supplies, enhances the fishery by reducing pollutants and suspended sediments, and improves the scenic qualities of a stream. Wetlands and floodplains also are vital to the ecosystem, providing food for many species and homes or nesting grounds for countless migratory and native species. Wetlands and floodplains also play a vital role in flood reduction.
- Establish flood hazard districts according to FEMA requirements that prohibit land uses in the floodplain which cause flooding and potential contamination of streamside properties. No new development should be permitted within the 100-year floodplain of White Clay Creek or its tributaries. Land uses which increase computed flood elevations and/or impair the ecological functioning of the floodplain should be prohibited, as should those that cause flooding and/or pollution.
- Protect jurisdictional wetlands by requiring delineation on all development plans. Establish policies to minimize direct impacts and to establish a minimum buffer of 25 feet or more between the wetland and development activities. Using existing wetlands for stormwater management should be discouraged except where they are highly degraded and when a mitigation program is included.
- Protect jurisdictional wetlands by encouraging cooperation to use best management practices (BMPs) in and near wetlands.
Protect and improve water quality and stream habitat through riparian forest buffers.
The single most important natural system critical to maintaining the integrity of the White Clay Creek watershed is the riparian forest buffer (RFB). Riparian forest buffers are extremely important to the maintenance of stream health. RFBs are complex ecosystems that can help to provide optimum food and habitat for stream communities as well as mitigate or control nonpoint source pollution. Naturally vegetated stream corridors provide food, nesting areas and migration routes for wildlife. According to the USDA Soil Conservation Service (Technical Release #55), forest buffers can reduce the quantity of stormwater runoff by 30% over non-wooded areas.
Forested and vegetative buffers remove nutrients from runoff while trapping sediment. They have been called "living filters. A well-maintained forest buffer on each side of the stream can remove the majority of phosphorus, nitrogen and sediment from surface and subsurface runoff.
Riparian forest buffers provide the food sources necessary for a healthy aquatic community, and the shade essential for keeping streams cool. Leaf litter, snags and tree roots in RFBs provide the habitat necessary for a thriving ecosystem. RFBs filter pollutants from overland runoff, reducing sediment and phosphorus loads. RFBs can also lower levels of nitrate in groundwater before it enters streams, reducing algal growth in reservoirs and improving the quality of downstream drinking-water supplies.
- Establish land-use management policies that preserve existing RFBs. Identify where RFBs occur and develop land-use management standards to preserve these buffers. Standards should include the establishment and maintenance of an RFB tied to review of a site's existing and proposed development along with its natural features, including soil characteristics and capability, slope, runoff patterns and the presence of wetlands and floodplains. A minimum RFB of 100 feet as measured from the top of all streambanks should be maintained.
- The depth of the riparian forest buffers on public lands may need to be increased in order to protect fragile riverbanks from the impacts of public use, to maintain biodiversity, to protect aesthetics in park and preserve areas and to enhance protection to songbirds (especially neo-tropical migratory species), cavity dwellers, large mammals and threatened and endangered species.
- Establish, identify and develop land-use management policies to create new RFBs.
Protect and improve water quality and stream habitat through sediment and stormwater management.
Excessive and uncontrolled or untreated runoff can wreak havoc on water levels - it can cause flooding, which threatens human life, erodes land and damages property. When water levels are low, aquatic life is threatened and pollutants are concentrated, intensifying water-quality problems. Further, runoff carries such pollutants as nutrients from lawn and agricultural fertilizers, pesticides, road salts, oil products, fecal wastes and toxic chemicals. In addition, heavy loads of sediment, swept into the stream by runoff, greatly impact the viability of stream ecosystems, destroying fish and wildlife habitat and otherwise degrading downstream water supplies.
This objective recommends a stormwater management plan for the White Clay Creek watershed, as envisioned in Pennsylvania's Act 167, prepared by the White Clay Creek Watershed Management Committee in concert with all the watershed municipalities, Pennsylvania's DEP, and Delaware DNREC. The general goals of the plan should include:
- preservation of water quality in the watershed's streams, wetlands and groundwater resources;
- maintenance and improvement of water flows in all streams and watercourses;
- protection and sustenance of natural stream channels, and maintenance of flood-carrying capacity of streams;
- limiting modification to the natural terrain and alteration to existing stream channels and other drainageways;
- maximizing recharge of groundwater and encouragement of infiltration to sustain groundwater supplies and stream flow;
- control of runoff, erosion and sedimentation through measures that are on site or situated as close as possible to where stormwater is produced;
- promotion of innovative stormwater management techniques which focus on groundwater recharge and stormwater quality;
- protection of persons and property from serious harm and significant damage from flooding caused by excessive runoff;
- ensuring that each residential, commercial, industrial or public development home and yard is constructed with adequate drainage;
- designing and constructing public drainage facilities and water courses so as to require minimum maintenance;
- minimizing soil erosion and sedimentation; promotion of delayed runoff by requiring the use of on-site retention; and
- promotion of groundwater recharge techniques where feasible.
Widespread use of Best Management Practices (BMPs) will substantially reduce sediments and contaminated runoff from construction sites, on-site domestic sewage systems, and other land-modifying activities. Communication and application of BMPs should be accomplished cooperatively, with the White Clay Creek Watershed Management Committee working with volunteer organizations, private landowners, conservation districts, municipalities and the cooperative extension services.
In addition, municipalities within the watershed should consider the following provisions for adoption:
- Require stormwater management and soil-erosion and sedimentation control plans for all development activities.
- Require that the flow of water on a parcel of property not be harmful to streamside vegetation, creeks and streams, lakes and ponds, aquatic life and adjacent properties.
- Prohibit discharge of roof drains, foundation drains, sump pumps into a street, roadway or other impervious surfaces.
- Prohibit post-development runoff that exceeds the natural volume and velocity experienced prior to construction.
- Prohibit the disturbance during development of such natural drainage areas as wetlands, marshes and swales.
- Require that surface runoff control measures be designed to protect surface stream water quality, and restrict volume and peak-rate stormwater runoff during and after development to levels similar to or less than those prior to development. The cumulative impacts of similar developments should be considered in reviewing proposals.
- Permit grading and vegetation removal only from actual building areas; require the replacement of such vegetation after construction is complete.
- Adopt a runoff-reduction hierarchy that operates under the following priority sequence:
- minimize impervious surfaces to reduce runoff volume and decrease stormwater pollution loads;
- preserve natural drainage swales, overland flow paths and depressional storage areas;
- convey runoff via vegetated filter swales in new development or where natural swales do not occur;
- infiltrate runoff on-site where soil permeability favors this.
Protect and improve water quality and stream habitat through slope protection.
Disturbance of steep slopes creates and escalates erosion and sedimentation of streams. Strict performance standards limiting the nature, extent, type and timing of earth disturbances on slopes are needed to protect against erosion and sedimentation and the resulting loss in water-quality values. Local governments can restrict development on steep slopes, regulate development on precautionary slopes, establish standards for grading and stabilization, require sediment and erosion control plans for slope development, encourage steep-slope BMPs in farming and forestry and enact tree ordinances.
- Establish steep-slope districts severely restricting development of 20 percent or greater slopes. Permit only minimally disturbing activities thereon. Permit activities with potential to cause erosion, such as disturbance for access, only after detailed engineering review and with careful construction monitoring.
- Establish precautionary-slope districts restricting extent of development on slopes of 15 to 20 percent. Permit development activities thereon only after detailed engineering review and with thorough construction monitoring.
- Establish performance standards to limit the extent of disturbance and impervious surfaces permitted on precautionary slopes. Include standards for grading and stabilization.
- Require sediment-and erosion-control plans for all development activities on all slope districts and within 500 feet of any creek, stream or run. Monitor construction activities to ensure compliance with plans.
- Encourage use of steep-slope BMPs in farming and forestry activities.
- Encourage the enactment of a tree ordinance.
Sustain biodiversity through habitat linkage and management.
Development is shrinking and isolating the watershed's stands of mature forest, which represent some of the last vestiges of native habitat in the watershed. Communities can plan such open-space links between forest segments as greenways, riparian forest buffers and other protected lands. They can monitor critical habitat areas and the wildlife in them, and establish programs to protect threatened species.
- Establish planning and monitoring programs for critical habitat areas.
- Establish programs to protect existing habitat and wildlife communities.
- Establish programs to preserve threatened and endangered species and critical habitats.
- Establish and expand programs to link critical habitats through riparian buffers, protected lands and greenways.
Encourage dedication, purchase and stewardship of open space.
Maintaining open spaces for agriculture, forest and recreational purposes helps to support natural ecosystems and enhances the quality of life for residents of the White Clay Creek watershed. Some important functions of open space include protection of water quality, protection of water supplies by recharging aquifers, control of erosion and sedimentation, maintenance of fish and wildlife populations and provision of areas for active recreation.
Programs to dedicate open space by agreement, easement or purchase help to achieve this objective. Ongoing programs should continue and expand, focusing on such stream resources as floodplains, riparian areas and wetlands, in addition to areas with steep slopes or significant ecological features.
- Work in concert with government agencies, property owners and watershed associations to create an open-space management program that encourages public and/or conservancy ownership of open-space parcels where appropriate.
- Promote and support the use of restrictions, conservation easements, purchase of development rights, and similar innovative voluntary techniques for protection of open space on private land.
- Encourage open-space programs for wetlands, floodplains, riparian areas, mature forest stands and steep slopes where appropriate, and link open spaces via riparian stream buffers and greenways.
- Encourage and facilitate stewardship of private lands.
Protect historic, cultural and archaeological resources in the White Clay Creek watershed.
Part of the essential nature of White Clay Creek is the remnant of earlier inhabitants, another is the culture and tradition of people now living nearby. An essential component of any Wild and Scenic River plan is the maintenance of the record of past and present, especially for those resources that are directly related to the stream itself.
- Develop a historic, cultural and archaeological inventory.
- Develop a program to monitor the use of historic structures.
- Promote adaptive reuse of structures through local ordinances.
- Preserve sensitive archaeological sites by working in concert with state and county archaeological preservation programs and local historical commissions.
- Include historical commissions in the development process.
- Promote and support the use of deed restrictions, conservation easements, purchase of developments rights and similar voluntary techniques for protection of historic, cultural and archeological resources on private land.