Did You Know?

Everyone lives in a watershed!

A watershed is a drainage basin that collects precipitation which eventually drains to a common water body (e.g., stream, lake, wetland). Precipitation in a watershed may also sink into the earth to become groundwater. Depending on where you live, most of the water you drink comes from watersheds!





Water Monitoring

Sacrillo and Reilly Canyon

As a result of flooding in the Purgatoire watershed in July and early August 2013, the Sarcillo and Reilly Canyon gages are decommissioned. The Reilly Canyon stream channel has shifted approximately 50 feet west, isolating the Hydrolab. Additionally, the bank erosion on the west side of the channel caused a large tree to fall into the pool used for stage monitoring. The Sarcillo Canyon received more flooding in August that covered the channel with another foot of sediment. Bringing these monitoring stations back online will be very difficult and require significant channel excavation. More information on next steps will be provided over the coming weeks.


Reilly Monitoring Station – Before Flooding

Reilly Monitoring Station – After Flooding



Sarcillo Canyon Before July 15, 2013 Flood Event

Sarcillo Canyon After July 15, 2013 Flood Event



The surface water monitoring program was initiated during the 2010 annual spring snowmelt runoff. Historical streamflows in the Purgatoire River at Madrid (upstream of Trinidad Lake) show that snowmelt runoff generally begins in late-March/early-April and continues through late-June/early July. http://waterdata.usgs.gov/nwis

Tetra Tech personnel began implementing the monitoring program and began surface water sampling in April 2010, with appropriate access agreements being addressed in advance. The initial year of the surface water monitoring program was April 2010 through December 31, 2010.  The subsequent year’s monitoring program was January 1, 2011 and continue through December 31, 2011. The monitoring program continues annually on a calendar year basis, January 1 through December 31. Annual reports are generated in July, as provisional data is finalized and results are documented.

Tetra Tech provides responsible resource management and sustainable infrastructure services that encompass the full life cycle of solutions. More: www.tetratech.com

To help support the Purgatoire water quality monitoring project, Norwest Corporation, a local environmental consulting company, performs weekly maintenance on each of the nine gauging stations along the river and its tributaries. During these 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. A similar water monitoring project was implemented by Norwest Corporation in 2007 in the Apishapa Watershed located just north of the Purgatoire Watershed. To learn more about this program, please visit http://www.apishapawatershed.org/


Aquatic Life Monitoring in the Purgatoire Basin

Learn about the fish species and macroinvertebrates in the watershed! Download the powerpoint presentation.


Purgatoire River Watershed Monitoring Network

2014 Sampling Analysis Plan


Real-time Monitoring, Monthly Data & Reports

There is monthly data collected at 27 sites along the Purgatoire and real-time data collected at 9 sites in the watershed.  Data available on this website are provisional data that have not been reviewed or edited. These data may be subject to significant change and are not citeable until reviewed, approved, and published by Tetra Tech annually in a report format. 

The 2012 Purgatoire Watershed Monitoring Report is available and summarizes flow and water quality monitoring data and results.  Appendices  include ”Continuous Gaging Station Data” and Data Detail and Laboratory Analytical Reports”.  

Click on the links below to see provisional data, graphs, and reports.

Watershed Monitoring Objectives

The six objectives of the watershed monitoring program are:

  1. Provide water quality data to more fully understand and evaluate CBM influences on surface water quality and loading to tributaries and ultimately, the Purgatoire River both upstream and downstream of Trinidad Lake.

  2. Provide continued hydrologic and surface water quality data for the evaluation of the upper Purgatoire River and associated tributaries throughout various flow regimes.

  3. Evaluate chemical loads, trends in the concentrations, and assimilative capacity to develop management scenarios, creative options and control strategies to achieve permit compliance.

  4. Allow a comprehensive, site-wide comparison of water quality constituents of concern to applicable permit limits and WQCC water quality standards.

  5. Understand sodium adsorption ratio (SAR) and electrical conductivity (EC) relationship in the watershed as it relates to irrigated agriculture and classified uses.

  6. Provide a scientific and technical basis to support permitting decisions and water management options that could be presented to the Water Quality Control Division (WQCD) or regulatory options that could be introduced to the Water Quality Control Commission (WQCC) at a hearing for the Arkansas River basin in June 2013.