A goal of the Clean Water Act is to ensure that running water resources have physical integrity, which means it is in equilibrium and stable with its watershed. ADEQ is researching stream stability to understand how to better maintain and restore the physical integrity of Arizona's rivers and streams.
The objective of ADEQ's geomorphology research is to test, and if necessary develop reliable quantitative assessment tools by which we can determine with accuracy and repeatability, the functional state of a stream or river.
The stability of streams is associated with a balance between the variables which shape and maintain stream channels. A stable stream is one that over time maintains its dimension, pattern, and profile in such a manner that it is neither aggrading nor degrading and is able to transport, without adverse consequences, the flows and detritus of its watershed (Rosgen, 1996).
Most of the methods that ADEQ is evaluating have been developed by others (Bevenger and King, 1995; BLM, 1993; Harrelson, et al, 1994; Pfankuch, 1975; Rosgen, 1996). It is important that these geomorphology assessment tools be thoroughly tested under the environmental conditions found in Arizona before adopting them to support our water quality assessment and water quality standards programs.
To predict the potential impact of an activity on a stream or river the current physical state or stability of the waterbody must be known - that is, what is the river doing?
To determine this, reference conditions (least disturbed) and impaired sites are selected and the dimension, pattern, profile, bed material, and erosional processes are measured with a set of geomorphology assessment tools. Sample sites will be stratified by Rosgen stream type (Rosgen, 1996), and a geomorphology database will be created from which we will be able to determine the measurements that best describe stable conditions in Arizona streams.
Channel dimension is determined by measuring bankfull width and depth, bankfull cross-section area, width to flood prone area, entrenchment ratio, mean bankfull depth, width, width/depth ratio, pool depth and width, pool cross-section area, riffle width and depth, riffle cross-section area, ratio of pool depth to riffle depth, ratio of pool width to riffle width, ratio of pool area to riffle area, ratio of maximum pool depth to mean bankfull depth, ratio of lowest bank height to maximum bankfull depth, estimated mean velocity at bankfull stage, and estimated discharge at bankfull stage.
Channel pattern is measured by meander length, belt width, radius of curvature, meander width ratio, arc length, arc angle, ratio of radius of curvature to bankfull width, ratio of meander length to bankfull width, and sinuosity.
Channel profile is determined by measuring valley slope, riffle slope, average water surface slope, pool slope, pool to pool spacing, pool length, and the following ratios: riffle slope, pool slope, and run slope to average water surface slope; riffle maximum depth and run depth to mean bankfull depth; pool length to bankfull width; pool to pool spacing to bankfull width.
Other measurements include pebble counts of channel materials, modified Pfankuch channel stability rating, Bank Erodibility Hazard Index (BEHI), Proper Functioning Condition (PFC), determination of flow regime, stream size, stream order, meander patterns, type of depositional features, an assessment of stream channel debris/blockages, riparian composition, and an estimate of riparian density.
Channel dimension will be measured by a laser level, stadia rod with laser receiver, and a fiberglass measuring tape (Harrelson et al, 1994). Field measurements include bankfull width and depth, width of floodprone area, pool, riffle, run widths and depths, and cross-section measurements of riffles and pools. Ratios, cross-section areas, maximum and mean bankfull depths, bankfull mean velocity and discharge will be determined with the aid of "The Reference Reach Spreadsheet" developed Mecklenburg (1999 - 2000).
Field measurements of channel pattern determined with a fiberglass tape include meander length, belt width, radius of curvature, arc length, and arc angle. The Reference Reach Spreadsheet will be used to determine the remaining channel pattern attributes.
Channel profile measurements are taken with the laser level equipment and include riffle, water and pool slope, pool to pool spacing, and pool length. Ratios and other hydraulic attributes will be calculated by "The Reference Reach Spreadsheet." Valley slope will be determined with a topographical map or by ArcView software.
Pebble counts will follow the method described in Bevenger and King (1995) and by Rosgen (1996). Channel stability, a semi-quantitative measurement, will follow the procedure by Pfankuch (1975), expanded by Rosgen (1996) and modified by ADEQ for Arizona conditions.
Potential sources of erosion from banks will be determined with the BEHI method developed by Rosgen (1996). PFC (BLM, 1993) will be assessed at each site with the intent of stratifying this qualitative index with stream type and physical condition. Flow regime, stream size, stream order, meander patterns, type of depositional features, stream channel debris/blockages, riparian composition, and the estimated of riparian density will be determined on site with field forms developed by Wildland Hydrology, Pagosa Springs, Colorado.
Mercury is a toxic, persistent and bio-accumulative pollutant that is both a public health and an environmental concern. Mercury has a direct affect on the nervous system and has long been known to have toxic effects on humans and wildlife. The organic form of mercury, known as methylmercury (MeHg), is one of the most toxic substances known.
Over the past several years, ADEQ has found increasing evidence of mercury contamination in the lakes and streams throughout the state. As a result of this monitoring, ADEQ has issued fish consumption advisories on at least 12 waterbodies in widely varying locations throughout the state including Alamo Lake, Upper and Lower Lake Mary, Lyman Lake, Parker Canyon Lake. These waterbodies will now require development of a total maximum daily load (TMDL) and plan of implementation to improve water quality.
To support various departmental programs including TMDLs, ADEQ has developed a multi-media, multi-agency mercury strategy that focuses on preventing new mercury from entering the environment and reducing the contributions from existing anthropogenic sources.
Since eating fish is the single greatest source of mercury exposure for most people, preventing the entry of mercury into the environment is the best way to reduce mercury exposure that causes health effects. Another important aspect to the long-term strategy is to reduce the use of consumer products containing mercury, encourage new technologies that can reduce or replace the use of mercury and facilitate proper disposal of existing products at the end of their useful life. Implementation of the strategy will require participation from agencies including: Game & Fish, Health Services, Mines & Minerals, U.S. EPA, USGS, state/federal land managers as well as public and private partners.
The Mercury Strategy combines three separate approaches:
- Additional data collection and research to determine actual levels and sources of mercury in Arizona (ongoing)
- As the Arizona picture continues to be refined, develop an education and outreach program brochures, website materials and workshops -- aimed at specific populations sectors and/or users (short-term)
- Develop both regulatory and non-regulatory methods to reduce and/or eliminate the use of mercury per key sector (longer-term)
Fact Sheet: Fish Consumption Advisories (10/31/12)
Fish Consumption Advisories - Questions and Answers
- What is a fish advisory for?
Where a fish advisory has been issued, the Arizona Department of Environmental Quality (ADEQ), the Arizona Game and Fish Department (AGFD) and the Arizona Department of Health Services (ADHS) have reviewed information and are advising consumers not to consume or to limit consumption of fish from a particular lake or stream. This advisory does not limit recreational use of waterbody for fishing, bird watching or other types of recreation.
- Are there fish consumption advisories in effect in Arizona?
Yes. There are about 10 different lakes in Arizona where ADEQ, AGFD and ADHS have issued fish consumption advisories. These lakes include Parker Canyon, Pena Blanca and Arivaca in southern Arizona near Nogales; Alamo Lake, Upper and Lower Lake Mary, Soldier Lake, Soldier Annex and Long Lake in north-central Arizona and Lyman Lake in northeastern Arizona.
- How do these fish consumption advisories come about?
Mercury has been detected at elevated concentrations in fish taken from the specific lake as part of the ongoing monitoring conducted by ADEQ and AGFD. Average mercury concentrations of greater than 0.3 - 0.6 milligrams per kilogram (mg/Kg) in fish found naturally in or stocked in a particular waterbody may result in a fish consumption advisory being issued.
- Why is mercury considered harmful?
Mercury is a liquid metal that when consumed by living organisms is transformed to methylmercury (or "organic" mercury). While methylmercury has been linked to a variety of health effects, the primary basis for this fish advisory is its toxicity to the nervous system, including the brain. Most at risk are babies and unborn children whose mothers consume fish containing mercury during pregnancy or while nursing. Exposure to mercury at elevated concentrations can delay walking and talking and cause learning disabilities in children. If you have questions about eating fish during pregnancy or while nursing, please contact your health care provider. Additional information on this subject can be found at:
What if I've eaten fish from one of these listed lakes in the past, am I OK?
The process for calculating risks from exposure to mercury is very conservative. Methylmercury will naturally leave your body over time once exposure has stopped. This process occurs at a rate of roughly one half of the total amount in your body about every two months. If you have any questions about risks from mercury you may have consumed in the past, please contact your health care provider.
Where did the mercury come from?
Mercury occurs naturally in the environment and is found in small concentrations in Arizona soils. Cinnabar, a natural solid form of mercury, occurs as reddish veins in or near recent volcanic rocks. Seven of Arizona's 15 counties contain significant deposits with historic mining and exploration for the metal occurring in several areas, including Maricopa, Yavapai and Pinal counties. Mercury has also been used in many industrial and agricultural applications and also in placer mining. Mercury can enter lakes and streams from any of these sources and will build up over time, especially if a waterbody is dammed and the sediments cannot be naturally flushed out. It only takes an extremely small amount of mercury to contaminate a water body. To illustrate, one part per million (the same as one milligram per kilogram) is like one day in 2,739 years.
How did the mercury build up in the fish?
Once mercury has entered a lake or stream, it is readily taken up by bacteria found in sediments and sometimes within the animals themselves. Mercury can build up in tissues of insects and as these insects are eaten by predators and these organisms are, in turn, eaten by larger predators, the mercury concentration increases every step, all the way up the "food chain" to "top predators" such as the bass and walleye. Concentrations of mercury in large, older fish can be many times those found in the insects at the bottom of the food chain.
Is it safe to swim or wade in lakes with these advisories?
Yes. Once mercury enters an aquatic ecosystem such as a lake or stream, it is readily taken up by bacteria found in sediments. Once in the sediments, it is quickly accumulated in the muscle tissue of living organisms such as aquatic insects and fish where it generally remains, moving from organism to organism. In aquatic ecosystems the vast majority of the mercury is most likely contained in the organisms inhabiting that system, leaving only very small amounts in the water. ADEQ continues to monitor lakes and streams for mercury in both water and sediments to protect the public health and environment.
Is it safe to fish in these lakes?
Yes. Recreational fishing should not be affected by this advisory. It is safe for people of any age to handle fish in catch and release situations and, as stated above, contact with the water should not pose a risk.
Is this just an Arizona problem?
No. Fish consumption advisories due to mercury are common throughout the United States and Canada. All but six states have mercury advisories presently in effect. Fourteen states have issued statewide advisories on all lakes. The state of Minnesota alone has 937 mercury advisories in effect. In January, 2001, the U.S. EPA and the U.S. Food and Drug Administration jointly issued a fish advisory covering both commercially and recreationally caught fish, advising women who are pregnant or who may become pregnant, to limit consumption of all fish to one eight ounce fillet per week. For more information, please visit: U.S. EPA: Fish Advisories .