Lower Yakima Valley nitrates in drinking water

When you turn on your faucet, the water that comes out should be safe to drink. Unfortunately, this isn't true for some well users in the Lower Yakima Valley.

Groundwater in this area contains elevated levels of nitrate. While nitrates do not cause health issues for most adults, they make it harder for blood to deliver oxygen in babies, pregnant people, and people with conditions like anemia or heart disease. You may have heard this called "blue baby syndrome" when it affects infants.

Fortunately, doctors are required to report cases of blue baby syndrome, and to date none have been reported in this part of the Yakima Valley. We want to keep it that way.

We are working with other state and local government agencies to reduce nitrate contamination so everyone in the Lower Yakima Valley has clean, safe drinking water. We've designated a "groundwater management area" where we are focusing these efforts. This area is roughly the stretch alongside I-82 from Wapato to Grandview.

Here's an update on what we're doing and what you can do to protect your water.

How to protect your drinking water

Nitrates can't be seen or smelled. They can't be removed by boiling your water or using a water filter pitcher. Here's what you can do to stay safe.

• Test your well annually so you know what's in it. Your city does not test it for you, unlike if you are on a city water system. Call the Yakima Health District or state Department of Health if you need help interpreting your results.
• If your well has high nitrate levels, use bottled water or install a home filtration system like a reverse osmosis filter. Do not boil your water, which can increase nitrate concentrations. Contact us or the Yakima Health District for help figuring out your options.
• Keep fertilizers, pesticides, fuel, oil, animals, waste, and septic tanks at least 100 feet away from your wellhead.
• Make sure your wellhead seal is intact and that your well and septic system are in good condition.
• Don't pour chemicals like cleaning supplies and paints down your drain.

What we are doing to protect your drinking water

Nitrates can seep into the ground from human and animal waste, fertilizer, or commercial activities. Once in groundwater, nitrates can be pumped up by your well. Since there is no way to remove widespread nitrate contamination once it has reached the aquifer, we are working on many long-term strategies to reduce the overall amount of nitrate entering groundwater in the first place. We are also providing clean drinking water to people with unsafe nitrate concentrations in their wells. We are working with several government agencies to do this:

• Yakima Health District
• Yakima County
• Washington Department of Health
• Washington Department of Agriculture
• South Yakima Conservation District

Here's some of what we've been doing:

We are monitoring well water

• We have been regularly measuring nitrate levels in 170 wells in the Lower Yakima Valley since 2021. This includes 34 new wells installed randomly but evenly spaced throughout the area, in addition to existing private wells at 136 homes.
• The results tell us how nitrate levels are changing and how results may depend on seasonal variabilities or the conditions of a particular well. If these wells show lower nitrate levels over time, we'll know that our strategies to reduce contamination are working effectively.
• We sampled water from 1,059 additional wells to test for nitrates as of June 2025.

We are recommending agricultural and food processing practices that minimize nitrate releases

• We updated water quality permit requirements to prevent more nitrate from being discharged into groundwater. Facilities under this permit must responsibly manage manure, wastewater, and other activities that release nitrates.
• We are educating gardeners and farm owners about how to safely use fertilizer and manure to minimize nitrate pollution. We are helping interested farms improve how they apply fertilizer and prevent over watering crops, which can leach additional nitrates into groundwater.
• We are inspecting farms to ensure waste storage ponds (lagoons) and manure stockpiles meet regulations.
• We are strengthening composting requirements to prevent nitrate contamination released by decomposition.

We are improving sewage and drinking water infrastructure

• We are working with cities to expand public sewer and water systems so fewer homes use septic systems. Reducing the number of septic systems means fewer of them may fail or work improperly, which releases nitrates into groundwater.
• We are helping cities replace aging sewer systems and maintain wastewater facilities so they can adequately contain nitrates.
• We are providing people with instructions on how to maintain septic systems so they meet health and safety standards.
• We are continuing our successful septic loan program, which reduces the cost of repairing or replacing septic systems.

We are providing safe drinking water

• We regularly delivered free bottled water to 146 households whose wells have high nitrate levels.
• We installed 130 free home filtration systems.
• We are studying alternative drinking water sources, like building community wells or connecting well users to public water systems, so people don't have to rely on contaminated wells.

We also received state funding to continue providing bottled water to homes with high nitrate levels. Contact the Department of Health for more information and to see if you qualify.

For a full update, you can read more details in this progress report.