By Denise Lana,
For the Record is part of a series of informational articles aimed at helping clarify some of the hot-topic issues currently facing the city of Decorah. This week’s FTR spawns from a variety of recent issues, including a study of the city’s drinking water as well as the completion of the Decorah Drinking Water Protection Plan by Rebecca Ohrtman from Iowa Water Quality Consulting. Public Opinion’s Denise Lana sat down with city engineer Jeremy Bril and water superintendent Todd Ihde to dive deeper into Decorah’s water concerns.
DL: What initiated the study of the city’s wells and quality of its drinking water?
JB: The water study came to be from funding received through a grant from the Iowa Finance Authority for municipal water infrastructure. The goal of the project was to assess our sources of drinking water in the city to determine if there were better management practices that we could install in the watershed to help protect that drinking water source.
The consulting group performed testing to answer the questions: Where does Decorah’s water come from? How quickly do contaminants affect our water? What is the capture area of contaminants? A common misnomer is we get most of our drinking water from the river. The maximum amount of water the river contributes to the city is 20 percent.
This was an in-depth study to determine the impact of the ground water that feeds our monitoring wells and drinking wells. The city has two clusters of well fields, with three wells near the water department, known as the west wells, and three wells situated near Goose Island and the high school, known as the north wells.
TI: These wells were established for the city through the 50s, 60s and 70s. Most of the water comes from the ground, not the river. To be clear, there are no quality issues we have had with our water. Our water quality is very good, but the study revealed areas where potential things like contaminants could move through.
JB: Basically, what this study did is define and narrow down the capture area of groundwater sources for our wells. We did onsite field testing, pump testing and electrical probe testing, so we could better define our capture area – the area where most of the ground water comes from — so we would know where we would really need to concentrate efforts with maintaining a high-quality drinking water.
DL: So, Decorah’s water is good?
TI: It is. Water quality has never been an issue in the city of Decorah.
JB: But we want to be proactive to keep from having problems.
DL: The plan discusses 10-day and 30-day contamination alerts; what are those?
JB: The Iowa geological survey’s two goals were to identify our capture area and determine how quickly something dumped in that area could potentially enter the wells. Normally, as water moves through the ground, it is very slow. We’re talking months to years, potentially. When they did a worst-case scenario model, water from the capture area had a 10-day travel time and a 30-day travel time. That means, in theory, if something fell on the ground in the capture area, it would take only 10 to 30 days to contaminate the wells.
It may seem like 10 days is plenty of time to react and do something, but by the time it gets reported and we find out about it, in the grand scheme of ground water, that is a very short time.
DL: Why does it move so quickly to the wells?
TI: We have very shallow wells, and the geology here, it’s more porous.
JB: Because of where the river is and our wells are, near sands and gravels. Around here if you were to get a crack in limestone, water can fly through that. I think that under normal operating conditions, it is not that fast. But we wanted to know worst case.
DL: What does this mean for residents?
JB: It makes us more aware of lots of things: Do we need to be more concerned with the application of fertilizers or chemicals? Do we need to make sure we are not dumping anything questionable down storm drains?
TI: We ask residents to do an inspection of all areas near their residences to make sure there are no abandoned wells, septic tanks, or similar, which are rich sources for places for contaminants to get in.
JB: If anyone sees an odd pipe in the ground, or anything that appears to be below ground that seems out of the norm …
TI: Exactly. We recently discovered an old buried septic tank just by walking around and inspecting. If someone notices a pipe or they are getting a sink hole in their yard, those are potential signs. We want this report to be treated as an educational piece, and we hope that people will read it and be more aware. If anyone sees anything they are concerned about, please give us a call.
DL: Is water well depletion something to worry about?
TI: No. The recharge rate of our aquifer is tremendous. What we call water loss is reported yearly. With daily logs, what we report as pumped in a year should correlate equally with what the city bills. The difference between those two is water loss. Under 20 percent is relatively normal, and we’ve been running 15-17 percent for years. Every bit of water is accounted for with meters.
We aren’t going to pick up on every service leak going to a residence, especially with the more porous geological area of our ground. A small leak, if it finds the right crack, it will never surface. Normally, that is how a lot of our leaks are detected is they make it to the surface.
JB: We measure at the wells, and at the water meters at the houses and businesses.
TI: If we were to burst a city water main, our usage would go up, and we would drop off in levels, almost instantly. There are 2,800 water lines providing service in the town, and we pump a million gallons a day.
JB: We are water rich right now. The meat of this report is an action plan. Now that we know our capture area and the timing of things, do we need to update our drinking water emergency response plan? If there is a spill, what happens now that we know it’s a smaller area we need to focus on, and things may move faster.
TI: We have an emergency plan in place, but it’s not updated every month. The drinking water action plan includes contact information, websites, people, procedures — a flow chart how to proceed — if there is an emergency situation.
DL: Has Decorah ever had any water contamination situation?
TI: We have only ever had one incident that has ever affected the city water, in the early 1990s (1992) when a cleaning solution from a dry-cleaning business got into the public water supply.
JB: One contaminated well was continuously pumped— and all the water wasted—for seven straight years.
TI: A second well was pumped and dumped for five years.
TI: When most people turn on a faucet, they don’t think about where the water comes from and where it goes. We are very lucky here; we pump the water, and we do a little bit of chlorine treatment and that’s it.
JB: The water is pretty incredible here, and we want everyone to be more aware so we can keep it that way.
The final report will be posted soon on the city’s website, and any water concerns can be directed to City Hall at 563-382-3651.