Phosphorus and Suspended Solids TMDL For the Lower Fox River/Green Bay Area of Concern – Putting the Pieces Together Bud Harris, P. Sager, D. Scheberle, V. Harris, P. Baumgart, D. Robertson, K. Fermanich, M. Finney, J. Kennedy, J. V. Klump UW Green Bay November 2-3, 2005 Looking upstream from the mouth of the Lower Fox River to the DePere dam, one can see the industrial and urban land uses that have destroyed fish and wildlife habitat and that are the source of the high concentrations nutrients, suspended solids and toxic substances.

Fox-Wolf Basin (16,500 km2) Three Sub-Basins Lower Fox (1,580 km2) New London Berlin Oshkosh Neenah/Menasha Appleton Wrightstown DePere Mouth Fox-Wolf Basin (16,500 km2) Three Sub-Basins Lower Fox (1,580 km2) 41 Watersheds

Green Bay Area of Concern (approx 57.2 km2)

TMDL Requirements in Section 303(d) Clean Water Act TMDL Requirements in Section 303(d) identify impaired/threatened waterbodies (P listed in 303d in 2002) develop TMDLs for those waters 4

TMDL Definition Sum WLA + Sum LA + {MOS} = TMDL WLA = wasteload allocation (point source loads) LA = load allocation (nonpoint source and background loads) MOS = margin of safety (explicit or implicit) TMDL = total maximum daily load

TMDLs 303(c) 303(d) 303(e) Water Quality Standards Water Quality Controls* TMDLs * Water quality controls include regulatory as well as voluntary controls 6

Examples of how wq goals and TMDLs could be expressed Nutrient TMDLs Examples of how wq goals and TMDLs could be expressed Water Quality Water Quality Controls TMDL Goals nitrogen concentration phosphorus concentration chlorophyll-a conc. macrophyte density Carlson Trophic State Index tons of in-lake algal biomass pH transparency biological indicators such as health of fish or macroinvertebrates dissolved oxygen ..... annual or seasonal loading of nitrogen or phosphorus percent reduction in nitrogen or phosphorus ..... 7

How did we get here? Some important benchmarks 1965 Federal Water Pollution Control Act 1970 First Load Estimate for P and SS 70-80’s Sea Grant Green Bay Subprogram 80-90’s GBMSD Monitoring Program 1988 Green Bay Remedial Action Plan 1990’s Priority Watershed Programs 1990 State of Bay Report 1992 NEWWT 2003 Lower Fox River Watershed Monitoring Program 2004-05 SWAT modeling for load allocation

Changes? Total P in Green Bay

Changes? Average TSS in Green Bay

Changes? Secchi Disk in Green Bay

Target for TP Based on Algal Growth Rates in Green Bay Algal growth begins to decline at 45 ug/l TP At > 100 ug/l, growth rates do not increase

Defining the relationship between total phosphorous and algae Present ambient phosphorous concentration ■ Target level ▲

Secchi Depth Model for Lower Green Bay (by Paul Sager) Light penetration measured by secchi disk and light meter Secchi depth = 0.80 – 0.174 TSS – 0.17 VSS – 0.16 Chlor a (r2 = .69) Sea Grant and Paul Sager currently updating model using recent MSD data

Green Bay AOC TMDLs TMDL 15 riparian protection rotational grazing Phosphorus (P) & Suspended Solids(SS) Water Quality Goals Water Quality Controls TMDL riparian protection rotational grazing conservation tillage manure mgt stormwater mgt P rationing construction site mgt urban design P target SS target Secchi disk depth 45µg/l 50% reduction in P load 7.5 mg/l 50% reduction in SS load 1.5 m 15

Basin Load Partitioning Data from GBMSD, DNR,USGS New London Berlin Oshkosh Neenah/Menasha Appleton Wrightstown DePere Mouth Basin Load Partitioning Data from GBMSD, DNR,USGS Estimates by Dale Robertson USGS

Loads at Main Branch Sites

Smaller-scale monitoring to identify sources with greater confidence

Fox-Wolf Basin Point Source P Loads

TMDL Lower Fox River Basin (assume 50% reduction all sources) TMDL (P) = sum WLA + sum LA + MOS = 258,791 Kg/yr / 2 = 129,396 Kg/yr TMDL (SS) = sum WLA + sum LA + MOS = 81,600 mt/yr / 2 = 40,800 mt/yr

Possible Approaches STRATEGIES SS P SCENRARIO ONE SCENARIO TWO etc… Phosphorus in Soil kept at a stable 40 parts per million Vegetated Buffer Strip-installed on 100 percent of the 1:24k hydrology streams Phosphorus in feed for dairy cows is reduced by 25 percent Conservation Tillage current No Till (NT) the rest Mulch Till (MT), and all manure incorporated Intensive Rotational grazing in which 40 percent of dairy farms adopt SCENARIO TWO etc… Individual % Reduction SS P 0% 12.8% 3.5% 4.1% 0% 5.5% 18.7% 16.5% 14.1% 15.3%

Next Steps? www.uwgb.edu/watershed Satellite image May 19, 2000

Phosphorous Reduction Management Strategy What is the likelihood of success? Cost effectiveness Social acceptability Ecological integrity True cost pricing Political Will

TMDL Review Criteria 26 Is the TMDL approvable? Identification of waterbody/pollutant of concern Applicable water quality standards and numeric targets Technical analysis/supporting documentation Margin of safety & seasonality TMDL/loading capacity Wasteload & load allocations Reasonable assurances nonpoint source controls will be implemented if point source WLAs rely on those controls Public participation Monitoring plan (for phased approach) Implementation plan (not required) 26