Water Quality

Links:
http://www.cdphe.state.co.us/wq/PermitsUnit/ConstFactSheet.pdf
http://www.cdphe.state.co.us/wq/PermitsUnit/SWConstructionApplication.pdf

The following contains a summary of the Aspen area water quality testing results for the year 2001. Chloride levels continue their gradual decrease, both above town and in town. Since Sodium Acetate has been used as Aspen's deicer the biological oxygen demand (BOD) and Dissolved Oxygen (DO) levels have been normal, indicating lack of harmful effects from Sodium Acetate. Anomalous spikes in both Chloride and Calcium occurred in 2001 that did not occur in 1999 or 2000. Possible explanations for this increase could be lower water levels in 2001 (a natural cause for higher concentrations of Calcium) or sporadic episodes of non-permitted use of the City storm drains like swimming pool wastewater and cement dust or paint disposal. The Environmental Health Department plans to increase awareness through the use of storm drain signs explaining that these drain to the river.

BACKGROUND:
The City of Aspen began sporadic testing of the Roaring Fork River for Magnesium and Chloride in 1994. In 1999, because of concerns about harmful aquatic effects of chlorides, and possible health effects of heavy metals in the deicer, the City began using CMAK (Calcium Magnesium Acetate and Potassium Acetate) as its deicer. The next year the City switched to Sodium Acetate based on its greater snow melting effectiveness. Sodium Acetate is the most environmentally benign deicer available. It is considered somewhat inert, biodegradable, and is used on many airport runways because it is not corrosive. Its potential environmental disadvantage could be increasing the Biological Oxygen Demand of the waters, although our monitoring shows no effect.

Biological Oxygen Demand (BOD) is a measure of the oxygen used by microorganisms to decompose organic waste. When BOD levels are high, dissolved oxygen (DO) levels decrease because the bacteria are consuming the oxygen that is available in the water. When there is less dissolved oxygen available in the water, fish and other aquatic organisms may not survive. That is why staff has been monitoring the BOD and DO levels of the Roaring Fork River since August of 1999.

SAMPLING RESULTS:
Prior to 1999 we have limited data (13 samples covering the period of 1994 through 1998). Also samples were taken near the stream edges. Since the Environmental Health Department took over the river sampling in 1999, monthly samples have been properly taken from the middle of the river at each site.

Below is a graph of all of the chloride samples taken. It demonstrates the Chloride concentrations above Aspen at the Copper Bridge; in the middle of town at the Mill Street Bridge; below Mill Street at the Slaughterhouse Bridge; at the Aspen Consolidated Waste Treatment plant, and near Woody Creek. Mill Street is the only ongoing sampling location through town with data from 1994 to 2001. Its trend demonstrates a decrease in chloride levels from when Mag Chloride was used until now, although there is large variation from sample to sample. This may be due to weather, stream flow levels, or random variation. Chloride concentrations also dropped below town, but did not change much above town.


These two graphs show the levels of BOD and DO at each sampling site. Comparing BOD levels for the last two years, it is determined that the BOD fluctuation throughout the seasons is normal and probably not affected by the use of the City's deicer, Sodium Acetate. The DO graph demonstrates that the Roaring Fork River has sufficient levels of Dissolved Oxygen throughout town for a healthy aquatic environment.



The following graph illustrates the Calcium levels at each sampling site. It demonstrates Calcium levels were unusually high at all sample locations, including above town, indicating that background levels may be going up. Levels increased significantly through town and were especially high at the Slaughterhouse sampling site. (The deicer Sodium Acetate does not increase Calcium levels in a river or stream.) Also, Calcium is not a recognized pollutant. However, staff has seen several incidences of draining swimming pools and disposal of paint and cement dust into the storm drains and believe that the increase in Calcium could be related to these non-permitted uses of the City's storm drains. What is most concerning is that these illegal practices could be introducing other contaminants that could have a negative impact on the local aquatic life.


RECOMMENDATIONS:
Staff will continue to investigate the spikes in Calcium. Staff recommends a storm water education campaign. The campaign would include a press release and teaming with student groups to paint signs on the City storm drains. Staff will also increase enforcement of any illegal dumping into the river. Staff will continue to collect samples of Mg, Ca, Cl, BOD and DO at Copper, Mill and Slaughterhouse.
Please contact staff if Council has questions about the sampling program or is interested in discussing the recommendations in more detail.