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Color by Numbers Manual

Please bookmark this page to make it easy to refer back to this manual.

If you have questions not answered in the video or manual, see our Frequently Asked Questions below. 

We are delighted that you will be contributing to an ever-increasing database on the Color of our coastal waters! The strength of this effort is in the numbers of data points collected over time, so your participation is key.

This manual guides you through the seven steps in the process to help us measure the color of the Bay. You can download a printer friendly version of the manual here.

We now have a video to walk you through all of the steps of the Color by Numbers manual.

It covers both the registration process and the steps to take a measurement. You may want to follow the steps along with the video, pausing where needed to complete each part.

If you have any problems throughout this process, please do not hesitate to contact us. During office hours, Monday-Friday 9 a.m. to 5 p.m., call us at (207) 799-8574. Outside office hours, call or text (207) 370-7553.

Let’s get started.

The first four steps in this process should be completed before heading outside to take your measurement. They should be completed at one time and should take about 20 minutes.

For these first four steps, you will need the smartphone you will be using for measurements and a second internet-connected device (e.g. computer, tablet, or another smartphone) to help you get set up.

After you complete the first four steps, get outside and start measuring the color of the Bay by following steps 5 through 7.

  1. Create your account online
  2. Download the app onto your device
  3. Register your device
  4. Learn about the optimal locations and scheduling, adding measurement times into your calendar
  5. Take your first measurement
  6. Confirm that your device has been registered and that you have taken your measurement
  7. Share your measurement experiences with us

Thank you to everyone involved in the Citclops project for creating, and providing the EyeOnWater app and website utilized in this effort. You can learn more about those involved with the Citclops project here.

Step 1: Create your Account Online

NOTE: It will be easiest to use this digital version of this manual to create your account rather than a printed version of the downloadable pdf version. This will allow you to click on the links instead of having to type them into your browser. 

1.1 On a second device (not the phone you will use for measuring), create your user account by going to http://www.eyeonwater.org/color/welcome.php

Note: Use the exact link above. This is the most efficient way to create your account. Make sure not to use https, as the link will not work.

If you do not use the link above, first, be sure you land on the right website, not eyeonwater.com, but eyeonwater.org.

When you get to the site, here is how you can find the place to Create your Account:
→ Go to eyeonwater.org:
→ Go to upper right corner, click on Observations
→ Go to lower middle of the screen and click on View the map of colour

1.2 Go to the upper right corner and click on Create User Account

If you do not see the EyeOnWater color banner (see arrow in the image above):

On Windows Computer (Upper Right)

On an iPad or Tablet, make sure you are holding the device in portrait orientation.

On a desktop or laptop computer, you will need to resize the window to make the banner appear.

Generally, this means making the window the size of an iPad or magazine cover. To make the window smaller:

On Mac Computer (Upper Left)

→ Click the button for your operating system (see images to the right)
→ That will resize your browser window to the last used size
→ Move your mouse to the bottom edge of the window and change the size of window making it as tall as possible
→ Move your mouse to the right edge of the window and now make the width of the window narrower, until the banner appears

1.3 Fill in the fields: a username, email address, a password and the “prove you are a human” verification code. Please note: your username will be public on the EyeOnWater website and linked to the data you collect. Common usernames may not be available. Record your username and password. You will need this information to log into eyeonwater.org to see your data. Then click the “Create account” button.

1.4 Close the black pop up window (see example below) by clicking the “X” in the upper right hand corner.

1.5 Next, click “Login” in the upper right hand corner. Enter your email address, password, and click the green “login” button.

You will know you are logged in when you see “User:[your username]” in the upper right of the screen. DO NOT click on the User:[your username”] button! Clicking on it will log you out. If that happens, follow the instructions in this step—1.5—to log back in.

1.6 Click on “Register Device” in the upper right corner to prepare to connect your smartphone to your account by scanning a QR code.

You should see a screen like the one below. Keep this open while you walk through steps 2 and 3 to get your phone set up. The QR code is valid for only 10 minutes. Should it expire, please reload the page.

Step 2: Download the EyeOnWater app onto your smartphone

Cover artThere are two ways to download the EyeOnWater app, either search your phone’s app store or use the links provided here. Note: There are multiple apps called EyeOnWater. Download the one with the logo shown to the right.

Step 3: Register your Smartphone

3.1 On the smartphone you will use for measuring, open the EyeOnWater app.

3.2 Click the menu icon in the upper left hand corner.

3.3 Click “Register your device”

3.4 Click “Scan QR code”

3.5 Now you are going to use both devices—the one you used to create your account and the phone you will use for measuring—at the same time, to register the smartphone you will use for measuring color.
Hold the phone you will use for measuring color up to the QR code on the second screen. Your phone will automatically recognize and scan the QR code and then take you back to the “Scan QR code” screen.

PLEASE NOTE: It may seem like your phone did not scan the QR code as the website does not have a clear “your device is registered” signal. The moment your phone scans the QR code, your device is registered.

3.6 Close the app now.

If you never scanned a QR code before, your phone may prompt you to install a QR code reading app. You can follow the prompts to do so.

Step 4: Mark your calendar—When and where to measure

High tide between 10 AM and 2 PM is optimal for measuring. We have identified all dates and times this year that provide the tides and light needed for measuring. The dates in bold on this schedule are dates we want as many people as possible to participate. Please measure only during the Measuring Window.

4.1 Review the Optimal times to measure: The list is at the end of this manual and a printable PDF version can be found here. You can help us help the health of Casco Bay by integrating the Optimal Measuring Dates into your calendar and measure as often as you can! Thank you!

4.2 Find an optimal location. This will be a place where you:

  • cannot see the bottom
  • can safely hold your phone parallel to the water (a dock, or a boat; not a beach or shoreline)
  • you have the sun at your back (even if it is cloudy), shining over either of your shoulders.

If you have access to a kayak, sail, or power boat, we encourage measuring via boat. Since there is an hour-long window, you could take multiple measurements in a row, moving a few feet between each measurement.

You can measure color from tall piers, boats, and ferries; it is okay if you are several feet above the water, so long as you can clearly see the water.

If you are looking for location ideas, visit this google map for suggestions https://www.google.com/maps/d/viewer?mid=1GnNejvs3iTphjAPcUKhL67kBlPeHl2EK&ll=43.77502142181361%2C-70.06745724999996&z=11.

4.3 Plan your arrival time so that you have enough time to get to your location and find a specific measuring spot within the specified Measuring Window for that date.

Now, please read the rest of this before starting to measure.

Step 5: Measuring, step by step, using the EyeOnWater app

Next, get outside and start measuring the color of Casco Bay!

Please note: the app works best when you move through it step by step, not using the back buttons.

If at any point the app starts to act strangely or you have to go back, restart the app.

5.1 Go to your measuring location on the Bay.

5.2 Make sure your phone’s location service and cellular data or wifi is on. If you cannot use data or wifi, please see the Troubleshooting section below. While in settings, also consider turning your phone’s screen brightness up.

5.3 Be very careful with your phone. Do not drop your phone into the water!

5.4 Open the EyeOnWater app on your phone. Because you have already registered your device, the database remembers you and you do not have to sign in each time you record a measurement.

5.5 There may be a short intro, so after that, click Get Started.

5.6 With the sun at your back, hold your phone in portrait orientation and point your phone’s camera down toward the water, as directed by the app. Your phone should be horizontal to the water, and the app will let you know if your phone is not horizontal enough. When your phone is in the correct position, the screen will change. Continue to hold your phone in that position.

5.7 Use the camera icon on the screen to take a photo of the water. The coordinates of the location are captured at this time.

5.8 If prompted, you can pinch and zoom in, until you just see water. The part of the image that remains should be the best representation of the water as you observe it. This will crop the photo, removing anything non-water from the image.

Tap the green “DONE” at the bottom of your screen. Please note: This image will not be saved on your phone.

5.9 At this point you can stop holding your phone over the water. If it is sunny out, you may want to find shade where you can continue while still seeing the water. Be sure to remove sunglasses. This could distort your measurement. Tri-colored bars will sit on top of two versions of your photo. The photo you took appears on the left. On the right, there is a solid color, the app’s representation of the color of the water. Swipe the tri-colored bars across your screen to compare each with the color of the water you are observing to make a selection. No color will match exactly the color of the water, so pick the one that is closest. Tap the + icon on the section of the bar that best represents the color of the water. You can swipe the bars left and right to see all the color options.

Tip: You are looking for the closest match to the color of the water. The human eye can accurately match colors when viewed simultaneously, so look at the color bars and the water at the same time.
The app helps you in this process by providing a simplified representation of the color of the water. This may feel subjective, but the more measurements you take AND the more measurements we all collect over time, the more useful your measurements will be.

5.10 After you tap the “+” button on the color that best matches the color of the water, a new page pops up.

If it is raining, tap or slide the “Is it raining?” button.

If you see the bottom, tap or slide the “Do you see the bottom?” button.

Moving the buttons to green means yes.

Unless you are using a Secchi disk, do not say Yes to “Are you an expert?”

Click the green “SEND” button at the bottom of the screen.

This sends the image, your data, and the GPS location to eyeonwater.org.

5.11 When your see the “Thank you!” screen your measurement has been recorded and stored on your phone or uploaded to the website. This screen also shares more information about the measurement you just recorded.

Step 6: See your measurements online and confirm your phone was registered correctly.

Please note: The data uploads are a bit slower than they have been previously. Your measurements will actually show up in the Global measurements area of the website first.

After a few hours, you can also check for them in the My Measurements by going to http://www.eyeonwater.org/color/welcome.php. Click “Login” in the upper right hand corner and complete the login process. You can do this on your device’s browser app or from your computer browser.

Just above the map, on the left-hand side of the screen, click on “My Measurements.” The map will zoom in to Casco Bay and show your measurements. If you do not see measurements, your phone was not registered properly, or your measurements have not been delivered to EyeOnWater. See below.

Please note: Times are in Central European Summer Time.


If you cannot use data or wifi:
While you do not have to use data or wifi while measuring, it is ideal. If you do not use data or wifi, there are a few additional steps you will need to take. Note: You will need to have your location services on.
Follow the steps above and then

  1. Before leaving your measuring location: Check to see if your data is queued for upload:
    On the smartphone you use for measuring, open the EyeOnWater app.
    Click the menu icon in the upper left hand corner.
    Click “Queued Uploads”
    If you don’t see anything in the queue, take another measurement.
  2. Get to a place where you can connect to wifi.
  3. Reopen the EyeOnWater app.
  4. Click the menu icon in the upper left hand corner.
    1. Click “Queued Uploads”
    2. Upload your observations

If you do not see your measurements online:

  • Try the “If you cannot use data or wifi” steps above.
  • Re-register your device again, repeating Step 3 above.

Step 7: Share on Social Media!

We want to stay up-to-date on the color measurements you are taking and celebrate your participation in this effort!

A great way to do this is to share selfies or photos of the scenery you see from your measurement location. We are on Instagram, Facebook, and Twitter and you can use the hashtags #cascobay and #colorbynumbers to show us how you are getting involved. This also encourages others to get involved! If you are not on Social Media and want to share your experience with us, send an email to volunteer [at] cascobay [dot] org.

If at any time throughout this process you have questions, contact Friends of Casco Bay. During office hours, Monday-Friday 9 a.m. to 5 p.m., call us at (207) 799-8574. Outside office hours, call or text (207) 370-7553.

Thank you!

Color by Numbers Measuring Dates & Times


Wednesday, June 13, 10:47 AM – 11:47 AM
Thursday, June 14, 11:40 AM – 12:40 PM
Friday, June 15, 12:33 PM – 1:33 PM
Tuesday, June 26, 10:31 AM – 11:31 AM
Wednesday, June 27, 11:14 AM – 12:14 PM
Thursday, June 28, 11:54 AM – 12:54 PM
Friday, June 29, 12:32 PM – 1:32 PM


Thursday, July 12, 10:26 AM – 11:26 AM
Friday, July 13, 11:22 AM – 12:22 PM
Saturday, July 14, 12:17 PM – 1:17 PM
Wednesday, July 25, 10:07 AM – 11:07 AM
Thursday , July 26, 10:50 AM – 11:50 AM
Friday, July 27, 11:30 AM – 12:30 PM
Saturday, July 28, 12:07 PM – 1:07 PM
Sunday, July 29, 12:42 PM – 1:42 PM


Friday, August 10, 10:09 AM – 11:09 AM
Saturday, August 11, 11:05 AM – 12:05 PM
Sunday, August 12, 11:58 AM – 12:58 PM
Monday, August 13, 12:50 PM – 1:50 PM
Friday, August 24, 10:21 AM – 11:21 AM
Saturday, August 25, 11:00 AM – 12:00 AM
Sunday, August 26, 11:35 AM – 12:35 PM
Monday , August 27, 12:09 PM – 1:09 PM
Tuesday, August 28, 12:42 PM – 1:42 PM



Sunday, September 9, 10:47 AM – 11:47 AM
Monday, September 10, 11:38 AM – 12:38 PM
Tuesday, September 11, 12:27 PM – 1:27 PM
Sunday, September 23, 10:24 AM – 11:24 AM
Monday, September 24, 10:59 AM – 11:59 AM
Tuesday, September 25, 11:33 AM – 12:33 PM
Wednesday, September 26, 12:06 PM – 1:06 PM
Thursday, September 27, 12:41 PM – 1:41 PM


Monday, October 8, 10:29 AM – 11:29 AM
Tuesday, October 9, 11:17 AM – 12:17 PM
Wednesday, October 10, 12:03 PM – 1:03 PM
Thursday , October 11, 12:47 PM – 1:47 PM
Tuesday, October 23, 10:20 AM – 11:20 AM
Wednesday, October 24, 10:56 AM – 11:56 AM
Thursday, October 25, 11:32 PM – 12:32 PM
Friday, October 26, 12:10 PM – 1:10 PM
Saturday, October 27, 12:52 PM – 1:52 PM

To print a list of these dates, go to: https://www.cascobay.org/wp-content/uploads/2018/07/2018-Color-by-Numbers-Measuring-Dates-and-Times.pdf

To add these dates as a calendar in Google Calendar:

  1. On a computer, go to this link and download the calendar file: https://calendar.google.com/calendar/ical/cascobay.org_0ub5vgo7fa2vcpgh2icfp761ds%40group.calendar.google.com/public/basic.ics
  2. Import events into Google Calendar

    • After you’ve exported your events, you can import them into Google Calendar.

    • Open Google Calendar on a computer. Note: You can only import from a computer, not a phone or tablet.
    • In the top right, click Settings Settings and then 
    • Click Import & Export.
    • Click Select file from your computer and select the file you exported. The file should end in “ics”.
    •  Choose which calendar to add the imported events to. By default, events will be imported into your primary calendar.
    • Click Import.

To add these dates as a calendar for and iPhone, iPad, or Outlook:

Click this link and follow the prompts to add the events to you calendar: https://calendar.google.com/calendar/ical/cascobay.org_0ub5vgo7fa2vcpgh2icfp761ds%40group.calendar.google.com/public/basic.ics

Color by Numbers Frequently Asked Questions

I’m not feeling tech savvy enough to do the registration process because it seems really involved. Maybe I shouldn’t participate?
We’d love to help you get set up. The video and/or the manual should provide all the info you need. If not, you can call Sarah at (207) 370-7553. She’s happy to help!  Usually she can help you resolve your problem quickly over the phone. It is a bummer that registration can seem so difficult!

I’m having trouble accessing the EyeOnWater website.
Try clearing your browser cache: https://www.digitaltrends.com/computing/how-to-clear-your-browser-cache/

Then use http://www.eyeonwater.org/,  not https://

I’m not sure I’m picking the right color. The colors on the scale look really similar and I’m worried that I’m not seeing it clearly enough. What should I do?

  • Make your color selection based on the color of the water you are seeing, rather than the photo on your phone. Oftentimes, the actual water and the image look like different colors to you, so choose the color based on the real thing!
  • When on the color selection screen, at the very bottom you can see a mini version of the whole 21 color scale. Above, each of the 3 “colors” in a bar are actually one color, with 3 variations of that color.
  • When making your color selection, you are doing exactly the right thing by choosing the closest match. The tint, tone, or shade (how black, white, or gray it is) does not matter.
  • Try turning up the brightness on your phone to see the scale better. Just remember to turn it back down afterward to conserve your phone’s battery life.
  • If you are having trouble in the sunlight seeing the screen, see if there is a shady spot to view the scale more easily or create some shade using your body. The human eye can accurately match colors when viewed simultaneously, so make sure you can still look at the color bars and the water at the same time.
  • Volunteers and staff are finding that practice helps, and that your proficiency in judging color improves with practice.
  • It is fine that the FU values you chose and the app calculated are different; that is something we expect to look at in our analyses.

Can I get feedback on my measurement?

It is difficult for us to provide feedback on your measurements. Please know that the value of this project is in the the quantity of measurements taken. Keep participating, and we think you’ll start to feel more confident. Read the tips in the previous question; if you still have questions, give Sarah a call at (207) 370-7553.

Must the water surface be sunlit? Can I take measurements on overcast days?

The surface does not need to be sunlit, so you can take measurements on a cloudy day. On those days, don’t worry about where the sun would be if it were shining. During this pilot phase of the project, we need all different kinds of measurements. Taking measurements on cloudy days may help us understand how taking measurements under different conditions may be affected by weather conditions.

What about rainy days?

Yes, you can take measurements in the rain, as long as you can do so safely, keeping in mind that surfaces may be slippery. And don’t go out if there is lightning! Just be sure to answer/slide the toggle for the “Is it raining?” question on the send screen.

Are reflections and shadows a problem? On sunny days, the light makes it hard to take a measurement because a reflection is created in the photo or my shadow or a shadow from the dock or the boat is in the image.

Reflections and shadows are allowed, although do try to minimize reflections. Move your position slightly to try to avoid getting foam, debris, or other floating objects in your photo if you can. Make your color selection based on the color of the water you are seeing, over the photo on your phone. This is the best thing to do if the actual water and the image look like different colors to you, which happens a lot. During this pilot year, the more photos we have, the better informed we will be as we consider refinements and future efforts.

Zooming in may help.

  • On iPhone: you have to do it before you take the photo. As you prepare to take the photo, you will see two boxes, and the smaller box has small circles with arrows in them in the corner. place your thumb and index finger on these two circles and use that to “pinch and zoom” or crop the area, then press the camera button.
  • On Android: pinch and zoom the photo after you take it.

How close should I be to the water’s surface?

You don’t have to be that close. We take measurements off the Southern Maine Community College Pier, many feet above the water.

What should I do when my phone freezes or doesn’t let me take the photo? Using the back button doesn’t seem to work.

If your phone freezes or you need to go back a step in the app, we suggest closing and then reopening the app, and then start from the beginning of the process.

iPhone 8 or earlier

1. Double-click the Home button to show your most recently used apps.

2. Swipe right or left to find the app that you want to close.

3. Swipe up on the app’s preview to close the app.


Because each model is different, do a google search for how to do this on your phone.

How can I check if my photo uploaded correctly?

Images are visible almost immediately under the Global section, so you can quickly determine there whether or not your upload was successful. Your readings are not visible immediately in the My Measurements section of the website;  usually takes a few hours.

Should I take measurements outside of these times?

This year, please focus on these selected dates and times, which were chosen to maximize the accuracy of the data. They can be found above.

Can I take a test measurement?

Sure. We ask that you only submit measurements during the selected times; however, you can walk through all of the steps, just don’t click the green send button on the screen with the map.

Are you asking us to take photos at the same location each day? Or can we move to different locations?
Either way works for us! We want this effort to be easy to take part in, so we welcome photos from the same or different locations, based on where it is convenient for you to participate at the measuring times.

We need measurements from multiple people at the same location and we also want to get measurements at as many locations around the Bay as possible. Consider helping us fill in the observation map which can be seen here: http://www.eyeonwater.org/content/map.php?map_type=color&menu=2

What should I do if I made a mistake and hit send and I wasn’t ready?

You can find your measurement on the eyeonwater website and click on the date and time to open the details. In that new window, click the green “Flag This” button.

Color by Numbers metrics so far this year:

Color by Numbers resources: