top of page
  • sierrawatershed

Be A Beach Detective

Updated: Dec 22, 2020

An exploration of plastic pollution in Lake Tahoe

PC: UC Davis TERC by Bill Wynne

Grade Level:

  • K-12


Physical Science:

  • Structure and Properties of Matter

  • Molecules: Structure & Movement

Earth Science:

  • Human Impacts on Earth’s Systems

Tools & Materials

  • Microplastics-Beach Detective Data Sheet or Science Notebook

  • Pencil

  • Rope* to mark your plot area *You can also use sticks and rocks found at the beach to mark the boundaries of your test plot.

  • Buckets or containers for litter collection and sorting

  • Bag for disposing of litter

  • Ruler (if available)

  • Tweezers (if available)

  • Magnifying lens (if available)

To Do & Notice

1. Question: Is there a plastic pollution problem in Lake Tahoe?

  • Watch this video of Jenna Granger, SWEP Field Instructor introducing the Beach Detective exploration.

2. Make a Claim:

  • You have likely heard of the plastic pollution problem in our oceans.

  • Is there a plastic pollution problem in Lake Tahoe?

  • Why is plastic a problem?

  • What can we do to eliminate the problem?

3. Testing Ideas:

  • Setting Up for Investigation:

  • Watch this video created by our partners at the UC Davis Tahoe Environmental Research Center to help guide your investigation.

  • Head to a local Lake Tahoe beach near you with your Beach Detective Data Sheet (or science notebook) and the materials listed above.

  • Designate an area where you have space to conduct an investigation.

  • Mark a 1 meter by 1 meter square test plot. Use rope, sticks or rocks to designate the boundaries of your test plot. IMPORTANT: Try to place your test plot half above and half below the wrack line of the beach. Wondering what the wrack line is? The wrack line is the line of debris deposited by storm or wave action along the shore of the lake. If there is no obvious line of debris place your test plot anywhere along the beach where debris is present.

4. Conducting the Investigation:

Survey for plastics within your test plot.

  • Start by removing and discarding any large natural debris from your test plot. Natural debris includes sticks, grasses and other materials typically found in nature. These are not litter so they will not be included in our survey.

  • Look for the presence of plastic litter within your test plot and sort and count by size following these guidelines:

  • Start by sorting and counting the amount of larger: Macroplastics present in your test plot. Macroplastics are any plastic greater than 2.5 cm in size (larger than your thumb nail). Record the number of pieces of this size class on your data sheet or in your science notebook.

  • Then sort and count the amount of Mesoplastics present in your test plot. Mesoplastics are plastics that are smaller than 2.5cm and larger than 0.5cm/5mm (about the size of your pinky fingernail). Record the number of pieces of this size class on your data sheet or in your science notebook.

  • Then sort and count the amount of Microplastics present in your test plot. Microplastics are plastics smaller than 0.5cm/5mm (about the size of a grain of rice). Record the number of pieces of this size class on your data sheet or in your science notebook.

  • Identify the source material. What was the original object that the plastic pieces came from? If you aren’t sure, take your best guess.

  • Calculate the total number of pieces of plastic present in your test plot and record this data on your data sheet or in your science notebook.

  • Note the most common size class.

  • When data collection is complete be sure to place all litter collected in a trash bin to make sure they are removed from the environment.

  • Answer data analysis & interpretation questions on page two of the data sheet.

5. Analyze & Interpret Data:

Presence of Plastic:

  • Did you find a presence of plastic in your test plot? If so, what was the source material (larger bucket, bottle, straw, toy, etc.)? Where do you think the plastic came from (beach visitors, boating and other lake recreation, blown from another part of the lake?) Did you have more of a certain size group than others? Do you think there are nanoplastics (so small they cannot be seen without a microscope) in your test plot? Based on your data collection what happens to plastics in the environment? Do they break down (decompose) or do they break up (into smaller and smaller pieces)?

  • If you did not find a presence of plastic: Why not? Do you think your test plot is an accurate representation of the entire beach? All of Lake Tahoe?

  • Problem with Plastic: Why are plastics in the watershed a problem? Do smaller plastics create a bigger problem? Why?

  • What can you do? How can we reduce or eliminate the plastic problem in Lake Tahoe? See “What’s Going On” section for ideas or think of your own.

6. Communicate Findings:

  • Share your results with SWEP to let us know what you found on Lake Tahoe’s beaches by sending us photos or videos of your experiment. Post your photos on social media and tag us @sweptahoe on Instagram and/or to @swep4 on Facebook. Be sure to hashtag and follow #SWEPsnippets. If you cannot post directly yourself, send your photos or video to SWEP (

What’s Going On

What is Plastic?

  • Plastics are synthetic (human-made) materials that are created when long chains of polymers are bound together. Most modern plastics are produced from fossil fuels: oil, natural gas, or coal.

    • Poly = many

    • Mer = single units

Does plastic ever go away?

  • While plastic has become an invaluable part of our everyday life, the negative impacts have become very apparent. Plastics never go “away” even after we put them in the trash can or recycling bin. Only 9% of all plastic ever produced has been recycled. Plastics find their way into the natural environment and easily degrade into smaller and smaller fragments by UV light and physical abrasion from wind and waves. Plastic is the most common form of debris found in the oceans, and is typically portrayed as large garbage patches floating on the surface, rotating slowly with the ocean currents. But now scientists have evidence that plastic debris is not just a surface problem.

What are Microplastics?

  • Very small pieces of plastic (<5 mm or the size of a grain of rice) are known as microplastics. Microplastics are commonly formed through the breakdown of larger plastic items and small microbeads found in certain makeups, toothpastes and personal care products. These small particles can easily make it through sanitation and water filtration systems, posing a risk to aquatic life.

Plastics in the Environment:

  • While plastics have been extensively studied in marine environments since the late 1970's, the impact of plastics in freshwater systems, like Lake Tahoe, is still relatively unknown. In summer 2018, UC Davis TERC researchers conducted the first sampling around Lake Tahoe to quantify microplastics in beach sand. Microplastics were found at all beaches sampled. Microplastics are also found in water samples and snowpack samples in our region.

  • Fish and other wildlife confuse large plastics, such as grocery bags, bottles, and straws, for food. Larger fish eat this plastic and then a larger animal eats the smaller one, and the plastics work their way up the food chain. These plastics may alter the behavior of the animals caused by a chemical imbalance or cause the animal to believe it is full while obtaining no nutrients or substance. Animals are impacted by entrapment in larger plastic debris such as plastic shopping bags and fishing nets and lines.

What can you do to help?

  • Reduce the amount of plastic items you use in your daily life. Choose to use reusable and refillable items instead of single use items that get thrown “away”. Rethink your habits and behaviors and take more time to choose the right products that have no plastic packaging.

  • Join a community litter pick up day or create your own with your family.

  • Become a citizen scientist by using the UC Davis Citizen Science Tahoe application on your smartphone. This app helps collect data of the exact location where litter is found on the beach, how much of it there is, what kind of litter it is, and identifying solutions for this problem. Download the app and help clean up our lake! Watch this video tutorial from TERC to learn how.


  • UC Davis Tahoe Environmental Research Center has been collecting data on plastics in Lake Tahoe and is working to improve the health of our watershed. Click here to see their research so far.

  • There is a 72 mile underwater lake clean-up planned to help remove litter from the bottom of Lake Tahoe next summer. Watch this video about the “Clean Up the Lake” project or visit their website.

Going Further

  • Refuse single-use plastics! Commit to reusables and plastic-free alternatives!

  • Make upcycled crafts out of plastic materials that would otherwise end up in the trash or recycling. Give them a whole new purpose by turning them into something different that is useful and fun:

    • Start the Spring season with a home garden using plastic water bottles

Thank you to our many partners for supporting student's science, sustainability and outdoor learning experiences.

Please review SWEP's Terms of Use prior to using this resource.

184 views0 comments

Recent Posts

See All


bottom of page