Photo courtesy of Washington Department of Ecology
The Washington Department of Ecology plans to test hundreds of wells over 150 square miles of mostly farmland in Whatcom County next March to see whether groundwater quality has improved over 20 years.
A recent study involving 25 wells suggests nitrate levels are trending downward in the Sumas-Blaine Aquifer, Ecology needs to replicate the much-bigger 1997 study to confirm it, department hydrogeologist Barb Carey said.
“Groundwater is very variable over a short distance, so we can’t say those 25 wells are representative of 150 square miles,” she said. “It’s not definitive. That’s why we want to go back and look at the aquifer on a broad scale again.”
The study may provide a snapshot of how farmers in the heart of Western Washington’s dairy and berry industries are managing nutrients. In 1997, Ecology tested 248 wells and 21 percent had nitrate levels above federal drinking standards.
At the time, Ecology reported that the results confirmed a widespread problem in the aquifer and noted that dairies and raspberry fields were the most frequent land use upgradient of wells with high nitrate levels.
Nitrate, ubiquitous in the environment, is a public health concern at excessive levels, though studies on whether nitrate causes birth defects have been inconclusive, according to a 2015 statement by the U.S. Department of Health and Human Services.
Ecology estimates 25,000 to 35,000 people drink from the aquifer. The groundwater also reaches the Nooksack River, which for its size washes more nitrate into Puget Sound than any other river, according to Ecology.
Ecology followed up the 1997 study by monitoring a few dozen wells over the years. The 11 wells with the most complete testing records have all shown decreases in nitrate levels, according to an Ecology report issued last month.
The report focused on 25 wells monitored between 2003 and 2016. One in four did not meet drinking standards set by the Environmental Protection Agency, though nitrate levels declined in nine wells and increased in only one well. The other 15 wells had no significant change in nitrate levels, according to Ecology.
Whatcom Family Farmers spokesman Gerald Baron said the report shows nitrate levels are comparable with other agricultural areas and signals that improved farms practices are taking effect.
“It’s good news. The overall indication of decline is significant,” Baron said. “Clearly, it indicates manure lagoons are working and farmers are applying (fertilizer) according to regulations.”
Carey, who has taken part in monitoring the aquifer since 1995, agreed manure lagoons and manure-management plans implemented in the past two decades may be working.
“I think dairymen are aware of the importance of applying nutrients in the amounts and at the times that are most appropriate,” Carey said.
Ecology’s tests don’t identify the sources of nitrate, which include septic tanks. “Unfortunately, no,” Carey said. “That’s difficult to do, and it’s a very case-by-case basis.”
The aquifer straddles the U.S.-Canada border and is especially vulnerable to nitrate contamination, according to Ecology. The water table is shallow, and rainfall in the area ranges from 32 to 50 inches a year. Environmental groups are pushing for stricter regulations on dairies in the area.