MinnFARM Feedlot Runoff Compliance and Priority

Credits (and who to blame?) Base presentation prepared by MPCA for MPCA and County feedlot staff Revised by Al Kean, BWSR, for SWCD and BWSR staff

Topics Bit of history about FLEval Brief overview of MinnFARM (Minnesota Feedlot Annualized Runoff Model) Annual feedlot runoff Load Limits to define compliance with State water quality standards MinnFARM Priority INDEX to define noncompliant feedlot priority for financial and technical assistance Feedlot regulator Best Professional Judgment (BPJ) considerations

Key Reference Documents MinnFARM Users Guide: http://www.manure.umn.edu/applied/assets/MinnFARM%20Users%20Guide%202_0%20051508.pdf Evaluating Open Lot Runoff Compliance, MPCA, May 1, 2008 http://www.pca.state.mn.us/publications/wq-f8-35.pdf

FLEval Purpose and Approach 1980 – approximately 90,000 feedlots in MN 1982 – ARS – Create consistent, scientific tool to prioritize feedlots for environmental upgrades Approach – compute BOD concentration at Point of Discharge for 25-yr., 24-hr. runoff event, which related to MN water quality standards at the time Rating from 0 to 100, with 0 = 25 mg/l BOD at Point of Disharge for 25-yr., 24-hr. event 2002 – DOS version converted to Excel

MinnFARM Purpose and Approach FLEval is single event based, does not consider all seasons or all runoff events 2004 – EPA 319 grant to UMN to develop annualized feedlot runoff model (using Excel) Evaluates 4 seasons of year using rainfall and snow data from nearest weather station Computes annual loads of COD, P, N, BOD and fecal coliform at End of Treatment Priority INDEX considers annual loads and receiving waters (1 to 100, low to high priority)

MinnFARM Other Changes from FLEval Updated research Accounts for varying number of animals on the lot at different times of the year Incorporates width of buffer in calculations Can integrate compliance indication for multiple lots in one feedlot operation Designated Storm worksheet can evaluate specific storm events MinnFARM FLEval output removed

MinnFARM vs. FLEval Terms Feedlot – Area where animals are kept Same as FLEval Area 2 – Area that produces clean water flowing through the feedlot (yard water) Area 3 – Clean water flowing onto the buffer area Buffer – Vegetated treatment area for feedlot runoff End of Treatment (EoT) Related to FLEval Point of Discharge Water of Concern (WoC) Receiving waters for feedlot runoff not considered in FLEval

Drainage Ditch, Wetland, Buffer “Area 2” Feedlot EoT -Property Boundary -Road Ditch -Intermittent Stream -Water of Concern WoC = Lake, Stream, Drainage Ditch, Wetland, Tile Intake, Sinkhole Area 3 MinnFARM Schematic

End of Treatment (EoT) Point at which the runoff leaves the treatment area and: Enters a road ditch, Enters a intermittent stream, Crosses a property boundary (unless written agreement with neighbor) Enters a Water of Concern

Water of Concern (WoC) Receiving water for feedlot runoff (affects MinnFARM Compliance Indication and Priority Index) Lakes (>25 acres of open water) Perennial Stream w/wo lake Drainage Ditch w/wo lake Tile Intake w/wo lake Public or Non-public Wetlands Sinkhole or other direct conduit to Groundwater

Key Factors in MinnFARM Lot Size Reduce lot size and amount of runoff to allow for more treatment with less buffer Soil Types Model is greatly influenced by infiltration Only ½ of BOD can be settled out Area 2 and Roof Runoff Reduce amount of runoff through the feedlot and increase effects of buffer treatment Buffer Width Substantial effects on buffer treatment

Evaluating Open Lot Runoff Compliance (using MinnFARM) MPCA document number: wq-f8-35 Effective May 1, 2008 Minnesota requirements for open feedlots not required to have an NPDES permit Annual BOD and P Load Limits correlated to current State water quality standards (circa 1990) MinnFARM computes annual loads and uses load limits to indicate compliance

Load Limits Compliance Criteria Annual Load Limits correlate to State water quality standards: BOD standard = 25 mg/L monthly average and P standard for discharge to a lake = 1 mg/L total P monthly average If WoC is not a lake: Annual BOD Load Limit governs: at EoT = 50 lbs. plus 0.25 lbs. per 1000 lbs. of animal weight (AU) Max. annual load 125 lbs. regardless of feedlot size If WoC is a lake: Annual P Load Limit may govern: at EoT = 2 lbs. plus 0.01 lbs. per 1000 lbs. of animal weight (AU) Max. annual load 5 lbs. regardless of feedlot size

BOD Load Limit

P Load Limit

Interpreting MinnFARM Results MinnFARM is an indicator of compliance Does not guarantee compliance or non-compliance Room for Best Professional Judgment (BPJ) Soil types Runoff onto multiple buffers Buffer length and/or width, level spreaders, etc. Other sources of feedlot pollution (e.g. milkhouse waste, silage leachate, animal mortality handling)

MPCA Grandfather Policy For existing operations previously evaluated using FLEval No need to re-evaluate with MinnFARM unless…. Feedlot has changed in a way that significantly affects modeling results e.g. more animals, bigger lots, etc. Original design assumptions are no longer valid e.g. clean water no longer diverted, vegetated buffer not maintained (sheet flow, vegetation) FLEval analysis did not fit the situation very well e.g. very large operation, large runoff volumes, sensitive features nearby

Model Outputs MinnFARM FLEval has been removed Replaced with Yes or No for Regulatory Compliance INDEX – Used for prioritization ONLY Load Limits – Used for compliance Which load limit is used

MinnFARM Priority INDEX Priority Index from 1 to 100 (higher index = higher pollution potential) MinnFARM considerations include: Annual BOD and P load at EoT BOD Concentration at EoT Type of receiving water (WoC) Distance from EoT to WoC Not used for compliance indication

Example MinnFARM INDEX 1 acre lot with 100 AU, no buffer

Example MinnFARM INDEX 1 acre lot with 100 AU, 100 ft. good buffer, 30 ft. width

General BPJ for Compliance (Best Professional Judgment) Four items to consider MinnFARM results very close to the thresholds No threats to human health MinnFARM index is low (<10) Long ways to waters with aquatic life or marginal waters Farmed wetlands Type II that dry up annually Use all four items above for decision, not just one or two. Regulator to document reasoning in the file

Soil Type BPJ Big influence on the model results Soil survey is not always correct Type A soils are easier to get compliance Rapid infiltration may protect surface waters, but groundwater becomes a concern Consider a Nitrogen balance calculation on the buffer Enough grassed area to apply at agronomic rates Runoff analysis estimate (3 - 1 - 3) Require buffer size to be at least as large as for type “B” soils

Vegetated Buffer BPJ Some model runs will achieve compliance with less than 100 feet of buffer Consider having a minimum buffer length regardless of model results (at least 100 ft.?) Buffer width is important Wide buffers typically develop rills No treatment after 3 inches of flow depth Buffer vegetation type and maintenance Not all buffers should be called permanent meadow – vegetation maintenance is critical

Feedlot Runoff Treatment on Neighbor’s Property BPJ MPCA recommends not counting on neighbor’s land to treat feedlot runoff Can be used if a written statement is obtained by feedlot owner from neighbor Be aware this agreement could change at any point, making the model invalid in the future

Other Pollution Sources BPJ Milkhouse waste Feed Storage and Feed Pad leachate and/or runoff Dead Animal Treatment areas MinnFARM model does not account for these potential pollution hazards

Key Take-Away Information MinnFARM is the current feedlot runoff evaluation tool Annual BOD and P Load Limits are current compliance indication methods MinnFARM Priority Index is a key feedlot prioritization tool Evaluating Open Lot Runoff Compliance, May 1, 2008, wq-f8-35, is a key reference document

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