Urban Stream Syndrome

Purpose, goal, and standards

This activity examines urban stream syndrome and how urbanization affects stream banks. Urban streams often have issues with both physical structure and chemical composition. While this activity focuses on the physical changes, the chemical changes can be more important to the overall health of the stream. Even if a stream exhibits the physical changes described, it can still be untouched by urbanization if the chemical composition is normal. The opposite is true as well (see student problems 3 and 4).

After this activity, students should be able to:

Identify an urban stream based on bank structure.
Understand how urbanization affects the physical structure of stream banks. Students will examine the banks of 6 different streams to decide if the stream is exhibiting symptoms of urban stream syndrome.

**Correlation to the Next Generation Science Standards* (NGSS)**

Science and Engineering Practices	Disciplinary Core Ideas	Crosscutting Concepts
Developing and using models • Develop a model based on evidence to illustrate the relationship between components of a system.	ESS3.C Human Impacts on Earth Systems • Sustainability of human societies and the biodiversity that supports them requires responsible management of natural resources.	Cause and Effect • Empirical evidence is required to differentiate between cause and correlation and make claims about specific causes and effects.

Teacher instructions

Have students read the background section and answer any questions they have about urban stream syndrome.
Work through both problems in the Guided Practice section. Students will have answers provided for Guided Practice 1, but Guided Practice 2 should be done together as a class.
Once the class has completed the practice, have students work the following 6 problems individually. This should take 10 to 20 minutes.
If time allows, have students gather in groups of 3 or 4 to discuss their answers before sharing with the class. Give groups 10 minutes to discuss.
Share answers with students and discuss as a class any differences or difficulty students have with identifying affected stream banks.
Optional: Have students perform extension activity for homework or as an in-class project.

Guided Practice

Example 1: This stream appears to suffer from urban stream syndrome.
1) The bank is vertically steep, with 2) exposed soil.
3) The closest vegetation is primarily tree cover.
4) The water surface is significantly below the bank.

This stream appears to suffer from urban stream syndrome.
1) The bank is vertically steep, with 2) exposed soil.
3) The closest vegetation is primarily tree cover.
4) The water surface is significantly below the bank.

Have the class discuss Example 2 before beginning the assignment in full.
Example 2: This stream does not appear to suffer from urban stream syndrome.
1) The stream bed is narrow.
2) The stream bank is not steep.
3) There is riparian vegetation.
4) The bank has no exposed soil.
5) The water surface is almost level with the bank.

This stream does not appear to suffer from urban stream syndrome.
1) The stream bed is narrow.
2) The stream bank is not steep.
3) There is riparian vegetation.
4) The bank has no exposed soil.
5) The water surface is almost level with the bank.

Activity – Sample Answers

Does stream 1 suffer from urban stream syndrome? Yes
Why? The stream has concrete banks, no vegetation, and a wide stream bed. The bank is steep, and the water level is well below the bank.
Does stream 2 suffer from urban stream syndrome? No
Why? The stream has a small but existent riparian zone. It has a gently sloping, fully vegetated bank, and the water level is at or slightly below bank height.
Does stream 3 suffer from urban stream syndrome? No
Why? Although there are trees with exposed roots at the water level, there are no other hallmarks of an urban stream. The bank is fully vegetated, and water is at bank level. This is a mangrove-like area from a tropical forest.
Does stream 4 suffer from urban stream syndrome? Cannot tell
Why? This stream is clearly in an urban environment, but there is riparian vegetation and a low, gentle bank. Further testing (chemical, biodiversity) would be needed to classify it. (Some may correctly identify this as an example of urban stream restoration.)
Does stream 5 pictured here suffer from urban stream syndrome? No
Why? Although the bank on the left is steep, the bank on the right is flat. There is little riparian vegetation due to rapids, but there is still vegetation up to the water’s edge. The water level is at bank height.
Does stream 6 suffer from urban stream syndrome? Yes
Why? The stream has a steep, exposed bank, a wide bed, and no vegetation. The water level is below bank height.

Extension activity

Students can research another symptom of urban stream syndrome, like nutrient or toxin levels, and write a short paper on how the symptom changes stream structure in an urban environment. They should investigate which part of the urban environment leads to the change (structural changes such as road-building or input changes such as fertilizer) and available options to remedy it. Suggested symptoms for research: nitrogen availability, phosphorous availability, toxin levels, suspended sediment levels, temperature, hydrology, organic matter.

Have your students check out the Environmental Protection Agency website, an excellent resource they can use when beginning their research.

Urban Stream Syndrome
Student Guide

Name _______________________________________________________________ Date ______________________

Background

The environment in cities differs greatly from the environment outside of cities in several ways. Biodiversity is one of the first things people think about as being different when comparing a city to its surrounding environment. Although this is a significant difference, it is not the most obvious when comparing urban and non-urban areas. Easily identifiable differences are stream bed structure and water quality. Urban streams undergo both physical and chemical alterations, leading to both hydrology and biodiversity changes.

Urban streams often suffer from urban stream syndrome, which is characterized by changes in nutrient levels, hydrology, biodiversity, and other factors. In this activity, you will learn how to identify streams that suffer from urban stream syndrome based on visual evidence.

Changes in urban stream characteristics are caused by an increase in impervious surfaces resulting in increased run off and decreased water infiltration in urban environments. Lower rates of water infiltration lead to an increase in what researchers call “flashiness,” or large fluctuations in water flow volume and rate. Observable changes in the stream channel are important data for developing a model of urban stream syndrome. Other factors are tested to assess the total impact humans have made on a stream.

Use the chart below to familiarize yourself with stream channel characteristics and the differences between healthy streams and those showing symptoms of urban stream syndrome.

Characteristic	Healthy Stream	Urban Stream Syndrome
Width of stream bed	Narrow stream bed	Wide stream bed
Shape of stream bank	Flat/sloped stream bank	Vertical/steep stream bank
Riparian vegetation	Cattails, semi-aquatic species	Trees, terrestrial plants
Physical composition of bank	Unexposed soil	Exposed soil, concrete
Depth to water surface from bank	Level with riparian zone/bank	Deeper than riparian zone/bank

Directions

For the Guided Practice and Student Activity below, examine each image and indicate in the space provided if the stream appears to suffer from urban stream syndrome. Identify which physical features led you to this conclusion.

Guided Practice

Example 1: This stream does appear to suffer from urban stream syndrome. (The width of the stream bed is inconclusive.)
The bank is steep, with exposed soil.
The closest vegetation is primarily tree cover.
The water surface is significantly below the bank.

Example 2: Does this stream suffer from urban stream syndrome? _________________________________