Reducing Pathogen Pollution from Coastal Dairies

Researcher:

Rob Atwill
Environmental Animal Health and Medical Ecology
Veterinary Medicine
UC Davis
E.: ratwill@ucdavis.edu
T.: (530) 754-2154

Relevant Links:

Tools:

Revised:

August 3, 2010

A dairy farm above Tomales Bay. W. Miller/UC Davis

August 3, 2010

Contact: Rebecca Buddingh, California Sea Grant intern, sgintern@ucsd.edu

New California Sea Grant research shows that pathogen pollution from coastal dairies above Tomales Bay along Point Reyes National Seashore can be reduced with a few simple, easily adoptable farm practices.

These farming practices include: planting vegetative buffer strips of barley and rye grasses around areas holding calves; mulching lots with straw; removing manure from the ground prior to rainfall; planting seeds in the ground, and bringing cows indoors during part of the rainy winter season.

These conclusions are based on experiments conducted at five dairy farms following 13 rain storms over a two-year period and are significant because Tomales Bay is a major center of shellfish growing. Shellfish, as filter feeders, can accumulate water-borne pathogens.

UC Davis researchers led by veterinarian Rob Atwill, a specialist in waterborne infectious diseases, worked with dairies to investigate voluntary, inexpensive methods for reducing two specific types of protozoal parasites in farm runoff. These were Cryptosporidium spp. and Giardia duodenalis, which cause diarrhea and other illnesses in humans and other mammals.

A vegetative buffer strip below a dairy reduces pathogen pollution in runoff. M. Lennox/UC Davis

Their experiments show that young calves (less than two months old) are important sources of Giardia and Cryptosporidium. Planting buffer strips around areas holding calves and mulching the ground with straw in these areas were the two most effective practices for reducing these two pathogens in runoff.

In a separate yet related component of the project, batches of sentinel mussels were planted in three bays in Central California and analyzed for the presence of DNA from Cryptosporidium spp. This work highlights the sporadic yet widespread presence of the parasite, irrespective of proximity to livestock runoff and/or human sewage.

A dozen coastal dairies have voluntarily adopted some of the best management practices developed during this project, to improve water quality in watersheds of the Tomales Bay region.

To learn more about this project, visit http://www.csgc.ucsd.edu/BOOKSTORE/Resources/PP2010/R-CZ-180-Atwill.pdf