WATER QUALITY MONITORING
The initial goal of the ACWA water quality monitoring program was to set up an ongoing regime within the watershed to establish baseline water quality data. Once a baseline is set, ongoing water-quality monitoring can also track any potential changes as management practices in a watershed evolve across a number of farming operations.
There are numerous water quality parameters that can be evaluated, including: nitrates (nitrogen), phosphorus, bacteria, dissolved oxygen, temperature and turbidity - all common characteristics to use when evaluating the physical, biological, and chemical attributes of surface water.
Nitrogen is the main target in Iowa because it's easy to detect, it has been linked to hypoxia in the Gulf of Mexico, and it's the primary nutrient applied to farm fields in corn production. Nitrogen also represents a good starting point in the evaluation of changes in management, because it is one of the most easily manipulated practices on the farm.
Every watershed can have a wide variance of hydrologic conditions, and the Raccoon is not unusual in that regard. In our monitoring program, some of what we are doing is zeroing in on what we believe may be hotspots. That means we are looking for specific conditions — such as high nitrate or e.coli values — because we suspect they exist based on previous monitoring in specific areas.
For example, 42CA is basically is fed by tile lines, so elevated nitrate can be anticipated there, whereas 42A and 42B are at impoundment areas for flood control, and they seem to serve as reservoirs for e.coli survival between rain events. It is interesting to note that the highest nitrate sites are generally lower in e.coli and vice-versa.
In contrast, site 43 is the closest thing we have to a 'phase one background' site, which means that we are focused on the bigger picture there, and results there may appear to be more moderated. But all of them differ in characteristics and in what we see in terms of data coming out of them. From each snapshot, we can gain a better understanding of what we're dealing with in the watershed overall.
