Presentation on theme: "Stream Mitigation and Ecological Function in Mined Watersheds Todd Petty, PhD Division of Forestry and Natural Resources March 31, 2009."— Presentation transcript:
Stream Mitigation and Ecological Function in Mined Watersheds Todd Petty, PhD Division of Forestry and Natural Resources March 31, 2009
Jennifer Fulton Gretchen Gingerich Eric Merriam Megan Minter Jenny Newland (CVI) Mariya Schilz Paul Ziemkiewicz OSM USGS USEPA Magnum Consol Argus Acknowledgments
The MTM Debate Extensive alteration of headwater catchments from surface mines Best available technologies are used to mitigate for necessary environmental impacts. Reclamation effectiveness in recovering lost headwater functions is unclear.
Headwater Functions Water Retention and Flood control Aquifer recharge Soil retention Organic Matter retention and processing Nutrient retention and cycling Support of vertebrate and invertebrate communities Transport of dilute freshwater and processed detritus, nutrients, and biomass to downstream systems
Pre-mining Function – Post-mining Function = Mitigation Requirement - =
- = What functions are being lost from the native catchments? To what extent, if any, are reclaimed areas functioning as headwater catchments? What are the remaining functional deficits? Can deficits be met on-site through improved reclamation? Can remaining deficits be met and justified through off-site restoration actions?
Functional Value of Reclaimed HWs 5 Reclaimed HWs 5 Paired Native HWs Compare and contrast functions Identify opportunities for improvement
Structural Differences Site CodeSite Type Age (Yrs) Elevation (m) Gradient (%) Canopy Cover (%) Emergent Vegetation (%) Average depth (cm) Mean Particle Size WHOKMine silt/clay ARGMine silt/clay STBRMine silt/clay SUTRMine silt/clay BIHOMine silt/clay UTHCRef cobble UTLFRef cobble UTMCERef gravel UTMCWRef gravel UTWORef cobble
Water Chemistry Average Seasonal Measurements Parameter MinedReference MeanRangeMeanRange Conductivity (μS/m) DO (ppm) pH Q (cfs) Temperature (°C) Al (mg/L) Ca (mg/L) Fe (mg/L) Mg (mg/L) Mn (mg/L) NO3 (mg/L) – Se (mg/L) TP (mg/L)
OM Retention Artificial Sticks P. ChannelReference
OM Decomposition P. ChannelReference
OM Processing Power* 100 g of detritus enters into a 100 m channel segment on day 0 Processing Power = total amt decomposed within the 100 m segment over some period of time (400 days). Over a period of 400 days: 64 g of OM are processed within the reference channel 54 g of OM are processed within the reclaimed channel Leaves a functional deficit of 10 g OM processing power per 100 m per 400 days *Highly Preliminary!!!
Dissolved Carbon P. Channel Reference WHOK is a young mine – all C is inorganic (bicarbonate) DOC tends to increase with mine age (except for BIHO?) DOC lower in reference streams, but dominates TC (no bicarbonate) Dissolve carbon paints a good picture of ecosystem processes. OM stewing in mined channels. OM chewed up and spit out of reference channels.
Reclaimed HWs are fully transformed and differ markedly from native catchments with regard to structure, vegetation, and sediments. Reclaimed catchments support altered, but productive, invertebrate and vertebrate communities. The OM processing functions of reclaimed HWs are altered but largely retained – there is a measurable functional deficit that may be addressed through off- site mitigation. High TDS and elevated conductivity of outflows from reclaimed catchments may be the most important difference between reclaimed and native HWs. Reclaimed HWs Take Home
Focus on maximizing the wetland functions of reclaimed catchments vs. rebuilding lotic structures – Plant diversity, bird habitat, nutrient and OM processing, water and sediment storage Functional losses related to OM processing may be best addressed through off-site mitigation – Increasing OM retentiveness in small perennial streams nearby TDS problem is a big issue, and HW catchment protection may be necessary to maintain clean, freshwater sources in mined watersheds. Connections to downstream systems remain unknown. Improvements to Reclamation?
Pigeon Creek: Tools Needed to ID Off-Site Mitigation Opportunities and Put Into a Currency Transferable to the Impacted HW Catchments 30 Sites Drainage Area Gradient Habitat Quality Channel Complexity OM Retention OM Decomp
Relationship Between OM Retention and Stream Channel Complexity Makes it possible to predict the functional lift of a stream restoration project
Pre-mining Function - Post-mining Function = Mitigation Requirement - =
Calculation of Recoverable OM EcoUnits Associated with Stream Restoration Projects SITE NAMELENGTH Recoverable OM EcoUnit Elk Creek RF Oldfield Br Rockhouse Cr Pigeon Cr CVI-Universal Coal CVI-Oldfield Br Mouth LF Oldfield Br CVI-Oldfield Br Below Forks CVI-PC RR Bridge Pigeon Cr DS Rockhouse Cr CVI-High School Hell Creek Lower Mouth TOTALS1.64
What is the Functional Value of a Mitigation Project? 1.24 km stream length 0.68 km OM Retention Units
Reclaimed HW catchments are functioning very well in some ways, and not so well in other ways. OM processing Ecological Units can be used to make objective decisions about acceptable functional deficits from mining and functional lift from off-site mitigation. We must begin to address the TDS issue in intensively mined watersheds, which will require integration of HW protection into the decision making process. We have proposed a 4 Phase mitigation process, which can ensure the protection of HW catchment functions and maximize watershed scale ecological values. Conclusions
Overall Objective Ensure long-term protection of existing headwater functions and improve the functional value of riverine ecosystems in intensively mined WV watersheds. Phase 1 Maximize recovery of headwater functions through construction and permanent conservation of stream and wetland drainage networks on reclaimed surface mines and connect on-site structures to native drainage networks off-site. Phase 2 Enhance structural and functional characteristics of native drainage networks adjacent to the developed property and link these areas to reconstructed networks on-site (from Phase 1). Phase 3 Enhance structural and functional characteristics of native headwater drainage networks within the larger watershed of impact, thereby retaining stream structure and function at the watershed scale. Phase 4 Maximize ecological conditions and structural and functional characteristics of perennial streams at the scale of the larger watershed of impact (e.g., at the 8- or 10-digit HUC scale). A Watershed Scale Mitigation Process for WV Minelands