Water quality monitoring along the Delta Clearwater River has not been done on a consistent basis. Some tests were completed by the USGS in 1977-1980 and in the early 1990’s by the SWCD. In 2005 the SWCD initiated water quality monitoring to establish baseline data concerning the overall health of the Clearwater River and Lake. This report outlines the results of tests conducted in 2007.
Temperature
While temperature may be one of the easiest measurements to perform, it is also one of the most important parameters to test because it dramatically affects the rates of chemical and biological reactions within the water.
Clearwater River is well within range of Alaska water standards. 2007 result were similar to 2006 in that the warmest temperatures were in June with October being the coldest. In general, the river shows a warming trend as the water moves from upriver toward downriver due to solar heating. The exception was in October. The variation was very slight and probably due more to the temperature and amount of sunlight on the day of the sampling.
pH
pH is the measure of how acidic or basic a solution is. Generally, the ability of aquatic organisms to complete a life cycle greatly diminishes as pH becomes more than 9.0 or less than 5.0.
Clearwater River is well within Alaska Water Standards. The highest reading was at the lower stretches of the river during the April and October testing, but still below the 8.5 upper limits. This data corresponds well to data taken by USGS from 1977 – 1980, where their results ranged between 7.2 -8.2.
Dissolved Oxygen
Dissolved oxygen (DO) is one of the most important indicators of water quality for aquatic life. It is essential for the basic metabolic processes of animals and plants inhabiting our waters.
Clearwater River is within range of Alaska Water Standards for drinking, recreational (above 4 ppm) or aquatic habitat (7 – 17 ppm). Although the results were fairly constant through the testing season it shows a slight increase in dissolved oxygen towards the lower part of the river.
Turbidity
Turbidity is caused by suspended solid matter which scatters light passing through the water. Any material mixed and suspended in water will reduce its clarity and make the water turbid (i.e. muddy and cloudy).
Clearwater River’s name is well deserved. Its turbidity falls below even drinking water standards. Data collected in 2006 and 2007 falls slightly lowered than data collect by SWCD in 1992
Total Dissolved Solids
Conductivity measures the electrical conductance of water, which is proportional to the nature and quantity of total dissolved solids (TDS) in the sample water.
As has been the case with other tests, Clearwater River falls well below Alaska State Standards.
Ortho-Phosphate
Both phosphorus and nitrogen are essential nutrients for the plants and animals that make up the aquatic food web. Even a modest increase in phosphorus can, under the right conditions, set off a whole chain of undesirable events in a water body. These may include accelerated plant growth, algae blooms, low dissolved oxygen, and the death of certain fish, invertebrates and other aquatic animals. There are many sources of phosphorus, both natural and human. These include soil and rocks, wastewater treatment plants, runoff from fertilized lawns and croplands, outhouses and failing septic systems, animal manure, and runoff from disturbed land areas, drained wetlands, water treatment and commercial cleaning chemicals. Although there are no Alaska Standards for this, non-polluted waters will have less than .1mg/L total phosphorous which Clearwater River is below.
Nitrate
Together with phosphorus, nitrates in excess amounts can accelerate eutrophication, causing dramatic increases in aquatic plant growth and changes in the types of plants and animals that live in a water body. This, in turn, affects dissolved oxygen, temperature and other water quality indicators. Nitrates can get into water from fertilized fields and lawns as well as sewage and manure.
Clearwater River is below critical levels for nitrate levels. A water body should have level of <1 mg/L, which Clearwater is well under. The data does not show any clear trends. Since the nitrate levels are so low it is possible that there are interferences (movement of the instrument, air bubbles, scratches on bottles) in the sampling that caused the lack of consistency in the data. This data levels also corresponds well with the USGS data collected 1977 – 1980.
In summary, Clearwater River and Clearwater Lake are in very good condition in spite of increased activity. Testing will continue along the river and lake next year. Now that the Harding Lake Restoration Project is complete, tests will be performed at Harding Lake starting in 2008.
