Stream Monitoring

Another way to measure water quality is to consider the creatures living in the stream. Even small streams are home to fish, insects and other aquatic life. Assessing biological conditions involves conducting an inventory of the species of fish and insects living in the waterway. Some species are more tolerant of pollutants than others. Even polluted streams are home for pollution-tolerant species like the blacknose dace, mummichog or black fly larvae. If a species is present that can only live in very clean water, then this indicates that the water is healthy. Likewise, if only the most pollutant tolerant species can be found, then the water quality is likely impacted. Every spring, insects are collected at over 100 locations around the County and analyzed by species. Fish species are analyzed every summer in cooperation with the Maryland Department of Natural Resources.

Biological monitoring, watching and tracking the living things in our waters is one of the ways to determine that waterway’s health. By combining information on species living in streams with data from chemical analysis and the physical condition of the stream channel scientists determine stream health.

Fish Sampling

In the summer, teams of scientists and volunteers don their waders and head to the streams to count, weigh and categorize the fish. Pumpkinseed, stoneroller, white suckers, rosyside dace, greenside darters, brown trout and about 100 other species are catalogued during the survey. Fish are collected and then identified and weighed before they are returned to the stream.

Some fish species can tolerate a great deal of pollution and can live in conditions that other fish would not survive. During the survey, scientists record the number of different species, the types of species and the number of fish. They also weigh and measure the fish. The information that they collect is entered into a variety of mathematical formulas which provide an index, called the Index of Biological Integrity (IBI). This index allows scientists to quantify and compare for streams around the county and state.

Similar mathematical formulas are used to evaluate the insects in streams. The insects, like the fish, vary in their tolerance for pollutants. If particular species are found in a waterway, you can be relatively confident that the waterway is healthy.

Aquatic Insects

Every spring insects are collected from rocky, fast flowing, shallow sections of streams. These spots are called riffles and are the part of the stream referred to when we speak of babbling brooks. The insects we are interested in live between and beneath the rocks on the bottom of the stream and are called benthic macroinvertebrates. Benthic, because they live on the bottom, and macroinvertebrate because they are large invertebrates (without backbones.) Large is a relative term; the largest of these insects is a couple of inches long and the smallest, quite small, but still visible to the naked eye. Scientists sometimes refer to these pollution-sensitive insects as EPT. This is an acronym for the scientific orders Ephemeroptera, Plecoptera, and Trichoptera. Using macroinvertebrates as a measure for stream health is an easy and effective way to track changes in water quality. A "Dnet" is used to collect aquatic insects.

When the information on insect species is combined with a fish index and other monitoring efforts, the county gains a great deal of understanding about stream health. The IBI for insects is often referred to as the BIBI which stands for the Benthic Index of Biotic Integrity. Using these statistics, we are able to assign values to the biological health of a stream and determine if the health of the stream is improving or declining.

See for yourself how our natural resource specialists collect macroinvertebrate samples, examine them under the microscope and assess  the health of our streams by watching the short video, "Watershed Moments—Keepers of the Stream," featuring County Executive Johnny Olszewski.

We look to the life in the streams to determine whether the streams are healthy, but don’t forget that it is that beauty and diversity of life that we’re working to protect. You can join our science geeks looking for insects and counting fish. Check out the Maryland Stream Waders program and get your waders on.

Physical Stream Habitat

The physical condition of the stream refers to the state of the banks and channels of waterways. The survey examines whether there is significant erosion, if the channel is changing, if sediment is accumulating in areas and whether there is an abundance of debris or trash. These issues are all related to the physical condition of the waterway. Thirty sites are part of a long-term study to monitor erosion and other changes in the physical state of the waterway. In addition, Baltimore County is working to catalog all 2,100 miles of stream by having teams walk the streams and create reports on the stream and the area immediately surrounding it.

It is important to know what is in the water. An analysis of the chemical content of the water provides a snapshot of the quality of the water. Over 100 sites are monitored for chemical conditions six to eight times during the year. Another two locations are monitored monthly. Just as your doctor doesn’t randomly check for every conceivable disease during your annual check up, EPS conducts chemical analysis for nutrients, heavy metals, total solids and bacteria. These items are likely pollutants. Also, just like your own physician, if there are indications of a problem, additional tests may be conducted. 

Monitoring the water on a regular basis is important, because any individual sample is just a snapshot of stream conditions at that moment. Water quality conditions change constantly due to weather and other factors. For example, a sudden rain shower might flush nutrients and bacteria from nearby agriculture into the stream. Roads act as conduits for pollution, with stormwater washing sediment, litter and roadway contaminants into storm drains that flow directly into streams with no filtration. Other pollution sources can occur intermittently, such as a failing septic tank, wildlife scat and pet waste. 

Categories of Pollutants

• Nutrients—Nutrients like nitrogen and phosphorus are chemicals that are vital to growth in plants, but an overabundance results in the growth of large quantities of algae. Algae can cause algal blooms in the bay and create problems with oxygen levels and water clarity and contribute to dead zones. EPS tests for several different forms of nitrogen and phosphorus to get a complete understanding of how much of these chemicals are in our waterways. Sources of nutrients include fertilizers, sewage, wildlife, agriculture and atmospheric pollutants.
• Depleted Oxygen Levels—In addition to testing for the levels of nutrients themselves, we also measure for problems they can create, like poor water clarity and depleted oxygen levels. Total suspended solids and total solids are measured to gauge the clarity of the water. Biological Oxygen Demand (BOD) indicates the amount of oxygen required by aerobic microorganisms to decompose the organic matter in a sample of water. Chemical Oxygen Demand (COD) indicates the amount of oxygen that is needed to oxidize reactive chemicals in water. 
• Heavy Metals—EPS also tests for heavy metals, particularly cadmium, copper, zinc and lead. Heavy metals are generally toxic to both wildlife and humans and can cause a variety of problems. The metals often sink into the sediments in the bottom of streams and lakes and are particularly problematic for the aquatic life there. These metals can accumulate in some species of fish that people like to eat and can adversely affect human health.

Storm Drain Outfall Monitoring

Imagine yourself walking beside a small stream, in a park, or near your house. You are admiring the ripple of the water as it flows over the pebbly bottom and enjoying the shady trees that line the banks. Then you notice a large pipe, about 36 inches in diameter, protruding from the bank. That is a stormwater outfall. You notice a strange smell and that the water flowing from the pipe is discolored. You call Baltimore County to express your concerns.

Citizens exploring their neighborhoods or walking by these outfalls are the County’s best resource to insure that the outfalls are free of pollutants. Baltimore County's Illicit Discharge Detection and Elimination Program monitors the flow from the 3,509 outfalls in the County. However, the random inspections rarely result in identifying a problem because of the intermittent nature of pollutant flows from outfalls. Citizen calls and observations are the most effective way to identify problems with the storm drain system. Prompt response from the County leads to detecting and eliminating pollutants entering our streams.

Pollutants in Stormwater

Pollutants can enter the stormdrain system in numerous ways. Sometimes a citizen or company has illegally dumped oil, automotive fluids, or other substances in or near a storm drain. Municipal sewer lines might be leaking, blocked or overflow. A private septic system might have failed and leaked effluent into a nearby storm drain. Other times a pipe is illegally connected to the storm drain system. The pollutants resulting from these sources are often intermittent and not present or detectable during inspection. Citizen reports have been an effective tool in helping to protect our local waterways from pollution. You can report an environmental concern online.

How to Recognize an Illicit Connection

Illicit discharges can be identified in several ways. There may be unusual odors coming from the storm drain, stream discoloration, foamy discharge, or you may actually observe someone dumping trash or other materials. Usually storm drain inlets should not have anything flowing in them during dry weather. If you observe flow in a storm drain three days after a rain or snow event, this may be an illicit connection.

Illicit discharges can be intentional or unintentional, such as:

• Sewage overflows
• Leaking oil from cars
• Trash dumping
• Leaking septic tanks
• Improper oil disposal
• Laundry washwater

There are allowable exceptions that can be discharged, which include:

• Foundation and footing drains
• Air conditioning condensation
• Irrigation and lawn watering
• Springs
• Water from sump pumps
• Individual residential car washing
• Dechlorinated swimming pool discharges
• Water line flushing