Water Quality in Iowa

Why are we learning about water and watersheds. Select FOUR.

• It is an issue the community cares about (passing a $25 million water quality bond).

• Most Iowa waterways have high nitrate levels and this can affect our health in Iowa.

• The severity of flooding in our city (Ames) is affected by watershed issues.

• We have water issues right in front of us at Ames High (detention basins, Ioway Creek, etc.)

• The national standards (NGSS) call for us to study local watershed issues.

Answer explanation

The national standards call for us to design and conduct investigations about water (but do not call for us to study anything local). We choose to study local processes because it gives us the opportunity to connect with our community and it makes what we learn more relevant to our day-to-day lives.

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What is the main function of the regeneration zone in a natural swimming pool?

• To add chlorine and disinfect the water

• To filter and clean the water using biological processes

• To increase the temperature of the pool water

• To keep fish and insects out of the swimming area

Answer explanation

To filter and clean the water using biological processes
Feedback: The regeneration zone mimics a wetland ecosystem. Plants, bacteria, and gravel work together to remove nutrients and organic waste, keeping the water naturally clean.

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How do plants help maintain water quality in a natural swimming pool?

• By producing oxygen bubbles that kill bacteria

• By absorbing nutrients that would otherwise feed algae

• By releasing chlorine-like chemicals into the water

• By preventing sunlight from reaching the water

Answer explanation

By absorbing nutrients that would otherwise feed algae
Feedback: Plants take up nutrients such as nitrogen and phosphorus through their roots. This limits algae growth and keeps the water clear—just like in natural ponds or wetlands.

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Which Earth system process is most similar to how a natural swimming pool maintains balance?

• The greenhouse effect trapping heat in the atmosphere

• The carbon cycle recycling energy through the biosphere

• Wetland filtration of water through plants and soil

• Wind erosion moving sediment between ecosystems

Answer explanation

Wetland filtration of water through plants and soil
Feedback: Natural swimming pools imitate wetland filtration, where water passes through plants, soil, and microbes that remove contaminants and recycle nutrients.

We worked on defining what "high quality water" is. While natural swimming pools are great for people and fish (and other living things), some water characteristics are just good for fish, some are just good for people, and some are bad for both!

Groups:

(a) Just good for fish

,

(b) Just good for people

,

(c) Not good for either of us!

• High nitrate levels

• Low nitrate levels in drinking water

• Low bacteria levels

• High dissolved oxygen levels

• Some algae present (the base of the food chain)

• Excess algae growth (algal bloom)

• Clear water with little suspended sediment

• Moderate nutrient levels (not too low, not too high)

Answer explanation

Good for People

1. Low nitrate levels in drinking water – safe for human consumption; high levels can cause health problems.

2. Clear water with little suspended sediment – looks clean and is more appealing for recreation.

3. Low bacteria levels – indicates water is safe for swimming and drinking.

Good for Fish / Aquatic Life

1. High dissolved oxygen levels – needed by fish and other aquatic organisms to breathe.

2. Moderate nutrient levels (not too low, not too high) – support algae and plant growth at a healthy level for the food web.

3. Cool water temperatures – hold more dissolved oxygen and prevent fish stress.

Not Good for Either

1. High nitrate levels – can cause “blue baby syndrome” in humans and contribute to algal blooms that harm fish.

2. Excess algae growth (algal bloom) – reduces oxygen when it decomposes and makes water unsafe or unpleasant for use.

3. Muddy or very cloudy water (low clarity) – carries pollutants, blocks sunlight, and reduces water quality for both people and aquatic life.

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While algae look kind of gross in water, we learned that it is important to have algae in order to have strong natural communities in Ioway Creek. Reorder the following to show the role of algae within a food web sequence.

• Algae form the base of the food web, producing energy-rich compounds.

• Small fish eat zooplankton for energy.

• Larger fish eat the smaller fish.

• Sunlight provides energy for algae to grow through photosynthesis.

• Zooplankton feed on algae.

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Enlarge the picture to see our data on Ioway Creek species. Why might mayflies and caddisflies considered high-quality indicator species even though few or none were found in this sample?

• They are top predators in aquatic systems.

• They require clean, well-oxygenated water and disappear when pollution increases.

• They can survive in muddy or nutrient-rich water.

• They are invasive species that outcompete tolerant ones.

Answer explanation

These species’ absence in Ioway Creek signals that water quality may not be ideal—they’re sensitive to low oxygen and pollution.

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Enlarge the figure to view the data. What might the presence of many water mites (medium-quality species) and aquatic worms (low-quality species) suggest about the creek’s water quality?

• The creek is very clean and unpolluted.

• The creek has moderate pollution or low oxygen in some areas.

• The creek is completely polluted with no oxygen.

• The creek has too many predators keeping insect numbers low.

Answer explanation

The creek has moderate pollution or low oxygen in some areas.
Explanation: Medium and low-quality species dominate when water quality is not pristine. The mix of both suggests some clean-water habitats remain but others may be stressed or nutrient-enriched.

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Riffles are shallow, fast-moving parts of a stream where water tumbles over rocks and gravel. The moving water traps air and mixes in oxygen, creating a good habitat for clean-water organisms such as mayflies, stoneflies, and caddisflies. These species cling to rocks and rely on high oxygen levels.

Slow, muddy areas (also called pools or runs) have deeper, slower water. Fine sediments and organic matter settle to the bottom, which can reduce dissolved oxygen and increase nutrient levels. These conditions support more tolerant species, such as aquatic worms, leeches, and scavenger beetles, that can live in lower-oxygen environments.

Based on these descriptions, where did the Ioway Creek samples come from?

• Slow muddy areas.

• Riffles.

• Not enough information.

Answer explanation

Your teacher collected the samples from a slow, muddy area — the abundance of aquatic worms, flatworms, and scavenger beetles indicates fine sediment and lower oxygen, conditions typical of slower-moving water. It is also easier to grab this stuff than get into the water to explore the riffles!

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What is the main reason Lake Michigan’s water has become much clearer in the past 20 years?

• Increased pollution from nearby cities

• The disappearance of perch and trout

• The spread of invasive mussels that filter the water

• The removal of all nutrients from the lake

Answer explanation

The spread of invasive mussels that filter the water
Explanation: The text states that invasive mussels can filter the entire lake in just a few days, removing algae and particles from the water, which makes it appear clearer.

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