Northeastern Oklahoma (Ottawa, Delaware, Mayes, Cherokee, Craig, Adair, and northern Sequoyah Counties) is located in the Ozark Highlands Ecoregion (Omernik, 1987). This is a region of karst topography, eroded to form steep hills, valleys, and bluffs. Karst features include caves, sinkholes, streams, springs and complex underground drainage systems.

At one time, this area was covered in a shallow, tropical sea. When ancient marine organisms died, their calcium rich shells and skeletons sank to the bottom of the sea, forming thick calcareous deposits. Overtime, these deposits became today's bedrock of limestone and dolomite.

Limestone and dolomite are soluble in dilute acids. Water becomes slightly acidic as it takes up carbon dioxide while passing through surface soils. The dissolving action of this acidic water on these carbonate subsurface rocks produces today's karst features.

Consequently, karst areas, such as northeastern Oklahoma, contain numerous sinkholes, springs and streams that drain into subterranean caverns (i.e., caves). Water enters these groundwater systems rapidly as it passes through cracks and crevices in the ground surface, such as fractures in stream beds (i.e., losing streams), sinkholes, or fractured limestone under thin layers of permeable soils. Groundwater in karst areas can travel as quickly as a few thousand feet to over a mile per day. Degradation of sensitive, underground habitats and the associated groundwater can, therefore, occur rapidly in areas of karst topography. These and other characteristics of karst ecosystems make the underground environment relatively fragile and highly susceptible to human induced perturbation.

Many highly specialized and sensitive fish and wildlife species such as bats, amphibians, fish, and crustaceans (e.g., cave crayfish, isopods, amphipods) spend all or a part of their life in these unique and sensitive karst habitats. Federally-listed species that occur in karst habitats of northeastern Oklahoma are the endangered Ozark big-eared bat, gray bat, and Indiana bat, and the threatened Ozark cavefish.

Other high quality fish and wildlife resources in the Ozark Highlands include riparian corridors along streams and rivers, bottomland forest and other wetland habitats, and Ozark oak-hickory forest. These areas provide habitat for neotropical songbirds, birds of prey, bats, and numerous species of mammals, reptiles, and amphibians. Riparian and wetland vegetation also serves as a buffer to protect the sensitive high-quality karst watercourses from non-point source pollution by filtering sediments and capturing and breaking down nutrients and water pollutants (FISRWG, 1998).

Care should be taken to minimize impacts to these important fish and wildlife resources when construction projects are proposed in karst areas. We recommend the following Best management Practices to minimize impacts: (printer-friendly version)

• Implement a sediment and erosion control plan using best management practices during construction such as a) the installation of sediment fencing and straw hay bales to capture sediment, and b) stock piling any excavated material well away from streams and other karst features such as a cave opening so that the material cannot slough back into these areas (see also www.deq.state.ok.us/ECLSNEW/sitestrm.htm).
• Monitor sediment/erosion control measures after precipitation events. Clean, repair, and replace structures as necessary.
• Monitor sediment/erosion control measures periodically throughout all phases of construction. Clean, repair, and replace structures as necessary.
• Establish staging areas for the crew, equipment, hazardous materials, chemicals, fuels, lubricating oils, etc., no closer than 300 feet of a stream bank, sinkhole, spring, or cave entrance.
• Install sediment and erosion controls around staging areas to prevent discharge from these sites.
• Store construction waste materials, debris, and excess materials well away from karst features.
• Refuel construction equipment at least 100 feet from stream banks, sinkholes, springs, and cave entrances.
• Use the horizontal directional drilling method for proposed pipeline crossings of streams and wetlands, especially those streams which contain flowing water during project implementation to avoid impacts to these resources.
  • Prior to implementing a directional drill, a geotechnical investigation using the least intrusive means possible (e.g., ground penetrating radar, minimal exploratory bore hole drilling, seismic refraction and reflection, etc.) should be done to determine subsurface/geologic conditions that would be encountered along the drill path to ensure that a directional drill pipeline at the location would be feasible and not result in unnecessary damage to a sensitive area such as a karst void.
  • If the directional drilling method would not be feasible, we recommend that you:
    • conduct stream crossings during a period of low stream flow (July to October)
    • limit tree trimming and cutting to only what it is necessary
    • limit access of construction equipment within the stream channel to one confined location, preferably over an existing bridge, equipment pads, clean temporary native rock fill, or over a temporary portable bridge
    • limit in-stream equipment to that needed to construct a crossing
    • do not alter or remove natural stream features such as riffles or pools
    • place trench spoil at least 10 feet away from stream banks
    • use sediment filter devices to prevent flow of spoil off the right-of-way
    • de-water the trench, as necessary, to prevent discharge of silt laden water into stream during construction and backfilling operations
    • return the substrate and contours of the bank and bottom of the channel to pre-project conditions.
• Maintain natural stream features such as riffles or pools.
• Keep all machinery out of streams as much as possible.
• Limit the removal of riparian vegetation to only when it is necessary.
• Replace any woody riparian vegetation unavoidably lost by planting five trees for every tree lost. Only native riparian plants should be used to help prevent the spread of exotics.
• Contact the Service if karst features, such as sinkholes, springs, and cave openings, are discovered on the project site during any aspect of project implementation for further evaluation to determine if the feature is used by federally-listed species.
• Leave a wide natural vegetated buffer area around any sinkholes, springs, and cave openings (minimum of 300 feet), and along any streams (minimum 100 feet) located on the project site.
• Re-vegetate all disturbed areas as soon as possible after construction using only native plants to reduce soil erosion. Annual species, such as rye or wheat, may initially be planted along with native species in areas subject to immediate soil loss, such as a steep slope, to provide rapid erosion control. Final re-vegetation should use native species only.
• Plant a vegetative buffer of at least 100 feet around any sinkholes on the property if the vegetation was previously cleared.
• Apply fertilizers, herbicides, pesticides, or other chemicals no closer than 100 feet of sinkholes, losing streams, springs, and cave openings.
• Locate waste lagoons, storm water basins, feed lots, or septic systems away from sinkholes, springs, and caves.
• Remove and dispose of all debris and excess construction materials properly upon project completion.
• Evaluate the establishment of vegetation after project completion and inspect all sediment control structures at one month intervals for at least 3 months. Retain sediment control structures until site stabilization is achieved; and
• Remove temporary sediment/erosion control structures upon final site stabilization.

The measures most important to conserve listed cave species include 1) obtaining and utilizing knowledge of the cave locations used by the species, 2) limiting human disturbance to occupied caves, and 3) protecting known caves and surrounding foraging areas from habitat loss due to development. Essential information, such as the location of caves used by listed species, is often incomplete, and the extent of karst features in the vicinity of the proposed project may be larger than what is currently known. Undiscovered karst features, such as a cave opening and underground passages, may occur on or near project sites, even in previously developed areas. The Service recommends the following precautionary measures be taken to avoid impacts to federally-listed and sensitive karst species:

1. Survey the project right-of-way for karst features such as cave openings and sinkholes.

2. Establish a buffer area of about 300 feet around any caves or sinkholes found during the survey (or during any aspect of project implementation). The Service should be contacted for further evaluation to determine if the cave is used by federally-listed or sensitive cave species.

3. If a cave is used by federally-listed or sensitive species, we will likely require the cave to be mapped when bats are not present to determine if any additional openings or passages may be affected by the project. In addition, we may recommend modifications of the proposed project to allow additional buffer areas to be established. Incorporation of additional buffer areas may be necessary to avoid impacts to federally-listed or sensitive species.

4. In the event that holes or other openings are encountered during construction activities, no fill materials should be placed into the opening until Service or Service approved personnel have the opportunity to investigate the site thoroughly.

References

FISRWG. 1998. Stream Corridor Restoration: Principles, Processes, and Practices. By the Federal Interagency Stream Restoration Working Group (FISRWG) (15 Federal agencies of the U. S. Government). GPO item No. 0120–A; SuDocs No. A 57.6/2:EN 3/PT.653. ISBN-0-934213-59-3.

This list of Best Management Practices is not all inclusive. The list will be updated periodically, as needed. Please be aware that other federal, state, and local laws would likely apply to your construction practices.

Additional information from other agencies concerning regulations for development projects