Storm water events in a small agricultural watershed: Characterization and evaluation of improvements in stream water microbiology following implementation of Best Management Practices Robert D. Simon a, ⁎, Joseph C. Makarewicz b, 1 a Department of Biology, SUNY Geneseo, Geneseo, NY 14454, USA b Department of Environmental Science and Biology, The College at Brockport, State University of New York, Brockport, NY 14420, USA abstract article info Article history: Received 1 June 2008 Accepted 11 December 2008 Communicated by Bosch Index words: Storm water events Agriculture Small watersheds Stream microbiology Best Management Practices Both storm water event and nonevent flow contributed to the annual discharge from Graywood Gully, a small sub-watershed of Conesus Lake, New York USA, whose land use is 74% agriculture. While events contributed significant amounts of water in short periods of time, nonevents accounted for the majority of water on a yearly basis and could have flow rates matching those that occurred during events. Event storm water was elevated in materials associated with particulates such as total suspended solids, total Kjeldahl nitrogen, and total phosphorus. Water from high flow nonevents was elevated in soluble components such as sodium, nitrate, and soluble reactive phosphorus. As a result, events contributed the majority of particulates to the yearly loading from Graywood Gully whereas nonevents contributed the majority of soluble materials. The levels of total coliforms, Escherichia coli, Enterococcus, and total heterotrophic bacteria were elevated in storm water relative to nonevent flow, indicating that they acted as particulates. The median level of E. coli in nonevents was 200 CFU/100 mL whereas the median level during events was 3660 CFU/100 mL. Consequently, storm events accounted for 92% of all E. coli loading from Graywood Gully. Best Management Practices (BMPs) resulted in the mean, median, maximum and minimum levels of event-driven E. coli loading from Graywood Gully to decrease 10 fold over a 5-year period. The implementation of BMPs in the Graywood Gully watershed has improved the microbiology of event waters and consequently decreased the role that the watershed plays as a contributor of microbial pollution to Conesus Lake. © 2009 Elsevier Inc. All rights reserved. Introduction There are few more dramatic environmental occurrences in the Great Lakes basin than storm water events caused by extended periods of heavy rain and/or snowmelt. These events can transport large amounts of water and material into the lakes in a short period of time and are often associated with disruptive flooding. In the urban setting, storm water can transport significant amounts of heavy metals (Davis et al., 2001; Jartun et al., 2008), polycyclic aromatic hydrocarbons (PAHs) (Hoffman et al., 1985), and polychlorinated biphenyls (PCBs) (Hwang and Foster, 2008). Urban storm water runoff is also elevated in microbial pollution (Salmore et al., 2006) with sources such as pet waste and raccoons (Ram et al., 2007). In the rural setting, agricultural storm runoff may contain large amounts of soil due to erosion (Borah et al., 2003). In addition, runoff may contribute cow manure (McFarland and Hauck, 1999), wildlife fecal material, and agricultural pesticides (Smith et al., 2006). The growth of cities and suburbs has increased the need to manage rainwater runoff and to understand the capacity and behavior of combined storm water–sewer systems. Thus, significant community efforts in modeling of urban storm water events have been under- taken (e.g., Brezonik and Stadelmann, 2002). In contrast, planning and management for storm water flow in an agricultural watershed is the realm of the individual farmer and regional county agent who are often more concerned with prevention of soil erosion than they are in managing the storm water related pollution in runoff such as phosphorus (P) and fecal material. Compared to urban watersheds, the dynamics of pollutant drainage during storm water events in agricultural settings is not well understood. Graywood Gully is one of the smallest catchments (38 ha) in the Conesus Lake watershed. Land use is mostly in agriculture (74%) with a single dairy farm operation with approximately 100 head of cattle and row crops including corn and beans. For the past 5 years, “Whole Farm Planning” has been instituted at Graywood Gully, and a myriad of structural and cultural Best Management Practices (BMPs) aimed at controlling nutrient and animal waste pollution have been implemen- ted based on soil testing, evaluation of the P index, and field assessments (Makarewicz, 2009). The changes implemented, such as better manure management, installation of subsurface drainage, and Journal of Great Lakes Research 35 (2009) 76–82 ⁎ Corresponding author. Tel.: +1 585 245 5279. E-mail addresses: simon@geneseo.edu (R.D. Simon), Jmakarew@brockport.edu (J.C. Makarewicz). 1 Tel.: +1 585 395 5747. 0380-1330/$ – see front matter © 2009 Elsevier Inc. All rights reserved. doi:10.1016/j.jglr.2008.12.002 Contents lists available at ScienceDirect Journal of Great Lakes Research journal homepage: www.elsevier.com/locate/jglr