Monday, November 23, 2009

the manure problem

Horses are a way of life in the Ojai Valley, but the waste they generate has long been recognized as a potential water quality problem. The issue is nutrient-rich manure that is often disposed of adjacent to or sometimes in the creeks throughout the watershed. This elevates nitrogen levels in the water, which leads to excess algae. See previous blog post here.

A preliminary survey was recently conducted to evaluate the scale of the problem. The results were submitted in a memo to the Regional Water Quality Control Board who are currently considering regulatory approaches for the Algae TMDL.

According to the memo, the study was based on information from horse owners, site visits to the main horse locations, and well known horse locations. Based on this survey, there were 62 horses counted within the City limits of Ojai. And valleywide, excluding the upper Ojai Valley, the numbers shown on this map total 792 horses.
The memo further states:

It is believed that considerably more horses could be located with a more detailed survey. A more detailed survey would take many field trips and review of aerial photography. The detailed survey should yield at least twice the number horses shown in this preliminary survey. Many of the horses that are not yet counted will likely be on locations with 1-5 horses. Funding for a detailed survey has yet to be obtained.
At this time, the best estimate for total horses in the Ojai Valley (excluding the upper Ojai Valley) is 2000-3000 horses. If each horse has 30 lbs/day of solid waste*, that equates to 30-45 tons/day of horse manure.

*A 1,000 lb horse produces about 31 lbs of feces and 2.4 gallons of urine daily, which totals 51 lbs of waste per day. Pennsylvania State College of Agriculture Sciences study “Horse Stable Manure Management”