The City of Caldwell in Canyon County, Idaho, supplies groundwater to approximately 74,000 residents through some 25,000 connections. This aquifer-fed public water system relies on groundwater wells that draw water deep underground before treatment and distribution. Understanding how certain contaminants like 1,2,3-trichloropropane (TCP), a chlorinated solvent, are found in this water helps homeowners evaluate technical options for their household water quality.
Agricultural Land-Use History and Its Influence on 1,2,3-TCP Detections
Legacy Use of Soil Fumigants in the Region
Canyon County’s agricultural past involved the use of soil fumigants containing TCP as an impurity. These fumigants were applied extensively from the mid-20th century onward to control pests. Such historic applications contribute to the presence of small TCP traces in the groundwater system here, as documented in federal groundwater surveys.
Mapping Agricultural Areas to Detection Records
Areas with concentrated historic farming practices tend to align with locations of occasional TCP detection in groundwater samples. The agricultural footprint in Canyon County plays a role in the potential occurrence of the chlorinated solvent in the aquifer serving the Caldwell system.
Persistence of Soil Fumigant Impurities in Groundwater Decades Later
Slow Migration of 1,2,3-TCP into Deep Aquifers
TCP travelled gradually through soil and rock layers over decades after its use peaked, reaching deep groundwater supplies. The chemical's stability and low biodegradability mean it can persist long-term, even when surface applications ceased many years ago.
Delayed Appearance in Monitoring Samples
Federal monitoring conducted from 2013 to 2015 detected no 1,2,3-TCP above the reporting level (0.03 parts per billion) in 26 samples from the City of Caldwell public water system, evidence consistent with slow but limited migration into these groundwater sources.
How Sampling Parameters Influence Detection Expectations
Sample Depth and Well Characteristics
The depth of wells drawing water from the aquifer affects expected TCP levels. Deeper wells often tap older, more stabilized water with potentially lower TCP presence, whereas shallower wells may yield more variable results depending on contamination migration.
Source Type and Seasonal Variability
Groundwater as a source shows different TCP behavior compared to surface water systems. Seasonal changes can influence chemical concentrations, but multi-year monitoring in this region shows 1,2,3-TCP detection remains below measurable thresholds across seasons.
Pathways of 1,2,3-Trichloropropane into Local Groundwater and Distribution
Introduction via Past Agricultural Chemicals
TCP enters groundwater primarily through leaching from soils where fumigants containing this chlorinated solvent impurity were applied decades ago. Over time, this chemical migrates with water flow into aquifers supplying the municipal system.
Distribution System Dynamics
Once treated and distributed, 1,2,3-TCP concentrations in tap water reflect the source water quality and any treatment processes applied by the water system. Caldwell's water system records show no health-based violations related to TCP.
Interpreting Certified Laboratory Testing for TCP in Household Water
Understanding Test Reports for 1,2,3-Trichloropropane
Certified laboratory analysis reports TCP levels in micrograms per liter (µg/L), equivalent to parts per billion (ppb). Test results below 0.03 µg/L indicate levels below the federal reporting threshold, but only a specific test of your household water can determine its distinct concentration.
Test Result Limitations and Considerations
Absence of detection in a lab report means the constituent was not found above the reporting level, not necessarily that TCP is absent. Repeat testing under varied conditions may be advisable to characterize household water fully.
Seasonal and Multi-Year Variations Documented in Canyon County
Consistency of Non-Detects Over Time
Sampling from late 2014 to mid-2015 by EPA showed no 1,2,3-TCP detections above reporting levels in the City of Caldwell system. This suggests stable conditions with regard to chlorinated solvent presence at the municipal source over this period.
Potential for Changes with Land Use or Climate
While current records show no notable increases, changes in land use or groundwater recharge patterns could alter TCP behavior in the future. Ongoing monitoring remains essential to track any emerging trends.
In summary, Canyon County's groundwater system serving households shows no detected 1,2,3-TCP above reporting levels, reflecting legacy agricultural impacts and deep aquifer characteristics. Homeowners considering water treatment options have evidence to weigh approaches based on localized data and confirmed test results. The Pentair 1,2,3-TCP Filter provides a documented, ready-to-configure option to address any confirmed presence of this chlorinated solvent in household water supplies.
Where this information comes from
Source: EPA SDWIS public water system record. Sampled 2015-05-28. These figures describe the public water system's record, not the plumbing inside any individual building.
On record: EPA UCMR3 monitoring (2013-2015) for City of Caldwell (ID3140013), ID: 26 results across 1 listed contaminants, 0 detections above the reporting level; nothing detected above the method reporting level
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