Groundwater Vulnerability Is There a Groundwater Quality Problem

Groundwater Vulnerability

Is There a Groundwater Quality Problem? • U. S. Geological Survey, IN Dept of Environmental Management, USEPA, and IN Dept of Natural Resources assembled groundwater quality database • 18 pesticides and 5 “breakdown products” detected in 9% of samples

Is There a Groundwater Quality Problem? • Pesticides detected most often – alachlor, atrazine metabolites – di-ethylatrazine, di-isopropylatrazine – dicamba, 2, 4 -D, metolachlor • Nitrate above 2 ppm in 50% of sampled wells

State Groundwater Management Plan - Present • • Applies to pesticides Education/Outreach Best management practices Sampling wells

State Groundwater Management Plan - Future? • Necessary regulatory management approaches • Restrictions on pesticide product use where needed

DRASTIC Depth to water table Recharge (aquifer) Aquifer media Soil media Topography (slope) Impact of vadose zone Conductivity (hydraulic)

DRASTIC • Expert/numerical ranking model • DRASTIC Index D r. D w + R r. R w + A r. A w + S r. S w + T r. T w + I r. I w + C r. C w where r = Rating w = Weight

DRASTIC Ratings for Depth to Water

DRASTIC Factor Weights

DRASTIC D r. D w + R r. R w + A r. A w + S r. S w + T r. T w + I r. I w + C r. C w 8*5+2*4+8*3+6*2+7*1+1*5+7*3 = 117

Data Sources • NRCS State Soils Geographic Database (STATSGO) • Scale 1: 250, 000 • Info attribute tables • • • USGS DEM and geology IGS hydrogeologic unit maps IDNR and IGS water depths

DRASTIC Rating Table

Groundwater Vulnerability Issues • Based only on hydrogeologic factors • Does not consider land uses, management, pesticide properties • High or very high vulnerability rating does not mean pesticides will be present in groundwater • Low rating does not mean pesticides will not be present

Benefits • Provides reasonable estimates of groundwater vulnerability • Protects groundwater • Targets sites for education • Provides foundation for state groundwater management plan • Offers cost savings while improving groundwater protection