APISHAPA WATERSHED
Protecting Water Quality through Monitoring, Assessment and Education
FAQ
What is a Watershed?
Apishapa Watershed

A watershed is an area of land where water from rain and melting snow and ice drains downhill into a body of water. The watershed includes both the streams and rivers that convey the water as well as the land surfaces from which water drains into those channels.

What is "water quality"?
Apishapa Watershed

A method of characterizing water based on physical‚ chemical‚ and biological components in relation to a specific use. These characteristics are compared to set of standards and guidelines‚ set forth by various government agencies‚ to determine if the water is suitable for a particular use.

What are the water quality standards on the Apishapa River?
Apishapa Watershed

The Colorado Water Quality Control Commission (WQCC) established water quality standards for the Apishapa River can be found at
http://www.cdphe.state.co.us/regulations/wqccregs/.

What water quality parameters are being measured at the Apishapa Gaging Stations?
Apishapa Watershed

The Aqua Troll® 200 (instrument) measures temperature (ºC), pressure (PSI)‚ and resistivity (ohm-cm). These parameters are used to calculate depth (ft)‚ Actual Conductivity (µS)‚ Specific Conductivity (µS)‚ salinity (PSU)‚ Total Dissolved Solids (ppm)‚ and water density (g/cm³) within the instrument. In addition‚ water samples are collect and sent into a laboratory for analysis of various constituents including calcium‚ magnesium‚ sodium‚ and Sodium Adsorption Ratio (SAR).

What is Conductivity?
Apishapa Watershed

Conductivity‚ often referred to as electrical conductivity‚ specific conductance‚ and conductance‚ is the measure of the ability of water to pass an electrical current. Conductivity in water is affected by the presence of inorganic dissolved solids and is temperature dependent. All of the terms noted above refer to conductivity at a standardized temperature of 25 degrees Celsius.  Additional information on conductivity can be found at the following website:  http://www.epa.gov/owow/monitoring/volunteer/stream/vms59.html.

What is Sodium Adsorption Ratio (SAR)?
Apishapa Watershed

Sodium Adsorption Ration (SAR) is a measure of the suitability of water for use in agricultural irrigation, as determined by the comparative concentrations of calcium (Ca), magnesium (Mg), and sodium (Na) in water.  The equation used to calculate SAR is given as follows:

High sodium ions in water affect the permeability of soil and can cause infiltration problems.  This is because sodium, when present in the soil in exchangeable form, replaces calcium and magnesium adsorbed on the soil clays and causes dispersion of soil particles.  This dispersion results in the breakdown of soil aggregates.  The soil becomes hard and compact when dry and reduces infiltration rates of water and air into soil.  For more information on SAR, please visit:  http://www.ext.colostate.edu/pubs/crops/00506.html.

How do you get flow measurements?
Apishapa Watershed

Flow can be determined in a few ways and we use all three methods listed below as a quality assurance control measure. For our purposes flow is reported as cubic feet per second (cfs)‚ but it can also be reported as gallons per day (gpm)‚ million gallons per day (MGD)‚ or as barrels of water per day (BPD)‚ just to name a few.

Use of a flow meter: A flow meter measures velocity at various stages (heights) across a cross section of stream. These individual measurements are compiled and a total flow is calculated.

The staff gage: A stream height is read from the vertical scale on the staff gage.
Although‚ not used directly to determine flow it gives the user a general idea of stream conditions. Its critical use is in determining the rating curve.

The Aqua Troll® 200: The probe reads pressure (PSI) which is used to calculate depth of water (ft). These readings can further be calculated to predict flow.

What is a Rating Curve?
Apishapa Watershed

In hydrology it’s a graph of discharge versus stage (height) for a given point on a stream, in this case the gaging stations, where flow is measured with a flow meter at a cross section. Numerous measurements of stream flow are made over a range of stages and plotted as stage on the x-axis and discharge on the y-axis giving us step 1 of our rating curve. Step 2 involves plotting and correlating measured stage with the physical gage height reading.

Apishapa Watershed

How are these stations set up?
Apishapa Watershed

Apishapa Watershed

How often are the data on the website updated?
Apishapa Watershed

The Aqua Troll® 200 continuously reads data and records it internally at 15 minute intervals. The data are downloaded every 2 weeks‚ processed every 6-8 weeks‚ and tables and graphs posted to the website every 8 weeks.

Are there other water monitoring projects similar to the Apishapa Water Monitoring project?
Apishapa Watershed

Yes, the Purgatoire River Water Monitoring Project. This project consists of the collection and analysis of surface water data from 27 monthly sites (including 9 real-time sites) in the Purgatoire Watershed. This project was designed and implemented by Tetra Tech, Inc. with field support from Norwest including weekly maintenance at each of the 9 real-time stites along the river and its tributaries.  During Norwest's visits, the installed multi-meter probes are cleared of any debris and sediment to insure accurate water quality measurements.  The in-stream staff gages are cleaned if necessary and the staff gage measurements are recorded.  Field parameters are measured using a handheld YSI meter and compared to the installed multi-meter probe readings. Any identified problems are addressed during the site visit if possible, with Tetra Tech being notified of any complex problems.  Additional support is provided on an as-needed basis including collecting water quality samples and measuring stream flow.  To view information on the Purgatoire River Water Monitoring Project please visit:

www.purgatoirewatershed.org

Apishapa Watershed
contact us
Apishapa Watershed

Norwest Denver Office
950 South Cherry Street
Suite 800
Denver, CO 80246
Telephone:  303.782.0164
Fax:  303.782.2560
Email:denver@norwestcorp.com

Apishapa Watershed
Apishapa Watershed