Water Quality

CCG_8_text_boxColgan Creek’s main problem is thermal pollution. When water is too warm or polluted, the wildlife either dies or moves away to find a better home. Our goal is to make the water of Colgan Creek cool, clear and clean enough to support all riparian life forms, particularly trout—indicators of a healthy stream.

A Watershed Hero

To manage, you must measure. By measuring water quality in Colgan Creek, we provide valuable data for managing our resource. Water testing can make us into watershed heroes, as well. For example, in 2007, a Santa Rosa resident took water quality measurements in Colgan Creek and found that conductivity was too high. He reported it to the clean water authorities and investigators found that excessive amounts of animal waste were coming from the vicinity of the Santa Rosa Fairgrounds, entering storm drains and reaching the creek. Soon after that, the storm water system received long overdue upgrades— all because a watershed community member cared enough to monitor water quality. As Jack Williams, of Trout Unlimited said, “Citizen science is powerful.”
As we monitor water quality, we collect data which we can use to manage and protect Colgan Creek.

Watershed Heroes at Home

We can be watershed heroes by protecting water quality at home and around town when we keep toxins where they can’t reach the creek.

  • Store toxins properly When stored in damaged containers, toxins can leak and get carried into the storm drain. If put in the garbage, toxins can leak into the landfill and contaminate the water table.
  • Make certain toxin containers are intact, and stored above the ground.
  • Sonoma County has toxin pick-up services (not the regular garbage service) and drop-off facilities: www.recyclenow.org/toxics/house_tox_facility.asp

Creek-Friendly Car Care

CCG_8_used_oilTo keep car-dirt runoff out of storm drains, use a commercial car wash.

And since oil leaks can reach waterways via storm drains, keep a well-maintained engine, and get car oil changed professionally. Used oil goes only to a certified oil collection site.



Heroic Dog Care

CCG_8_dogAlways carry a plastic bag when you walk your dog. Keep dog poop out of the creek and off the creek banks (where it gets washed into the water by rain). Dog waste can release dangerously high levels of nitrogen pollution. And perhaps we all prefer nature walks without smelling, seeing or stepping on dog droppings.
No Pet Dumping, Please! Never dump your aquarium water into the creek. And do not release animals from the pet store—fish, turtles, mice, rats, snakes, birds or other non-native animals—into the watershed. These species can transmit disease to wild fish and other native animals. www.habitattitude.net

Keeping records of water quality data enables us to sound the alarm when pollution has entered the creek. Thanks to Elsie Allen High School biology teacher Jenny Fleisher, students perform all seven of these water quality tests in Colgan Creek.

Water Quality Monitoring



Water thermometer

Colgan Creek water is generally too warm to support trout, salmon or other cold-water dependent species.

When the newly planted native trees and shrubs begin to mature and shade begins to cool the water, conditions will get better.



Test strip for pH reading

Creek organisms need water with a balanced pH. In Colgan Creek, the lucky number is 7.

Each pH value < 7 indicates 10 times greater acidic. And for each number >7, the base is 10 times greater. If you find pH spikes in either direction, report it!

Dissolved oxygen

Aquatic animals rely on breathing oxygen that is dissolved in water. When the oxygen gets too low, these organisms die. In fact the entire creek can die. Cold water that travels swiftly contains more oxygen than warm, still water, so a healthy creek needs movement. Stagnant water has the lowest levels, and summer is the season when dissolved oxygen levels are predictably low.



conductivity meter

This test measures how well water conducts electricity.

High conductivity readings may indicate increased phosphates or nitrates. Oil contamination may lower conductivity.


Turbid water contains suspended particles that, in excess, can harm riparian habitat.


Nephelometer, for measuring turbidity

Turbidity can be observed with the eye, but for scientific purposes is measured in turbidity units via nephelometer (NTUs).


Phosphorus boosts plant growth, making water green and cloudy. When this extra plant life dies, it loads up the creek with rotting vegetation—reducing oxygen levels in the water. Phosphorus is measured in parts per million.


Nitrogen is a naturally occurring nutrient which, in excess amounts, causes a host of problems for water bodies, including algae blooms which harm aquatic environments and are extremely difficult to control. Nitrogen levels in water are measured in parts per million.