Water Management

Photo of Santa Fe Municipal ReservoirThis water management plan provides a framework for long-term monitoring that will help the City maintain a reliable, high quality water supply. Because ecosystem health of the upper watershed riparian corridor is directly related to both water quality and quantity within in the Santa Fe River within the upper watershed, this plan also specifies measures for ecosystem monitoring and potential habitat enhancement within the riparian corridor. The proposal will address three critical objectives for water management:

  • Maintain a reliable water supply,
  • Maintain a high quality of water, and
  • Enhance wildlife habitat and ecosystem function.

Water Management Recommendations

  • Maintain a reliable water supply.
  • Regularly test and measure stream flow, precipitation, reservoir level, and reservoir bathymetry or reservoir depth.
  • Stream Flow.

Stream flow is important to assess the quantity of Santa Fe River supply, both for near- and long-term management of the City’s water utility, as well as assessing the impact of management activities on the stream system. There are several deficiencies at the existing gages within the watershed that should be resolved to improve the ability of these gages to provide adequate data. The Santa Fe River above McClure gage is submerged when the reservoir level nears maximum capacity, and as a result doesn’t record discharge during these periods. We recommend that a new gage be installed further upstream in order to avoid submersion problems. All three of the primary stream gages have automated data recording, but none of them are equipped with telemetry to transmit data for satellite uplink and subsequent on-line posting. To resolve this, SCADA telemetry should be installed at all three gages.

Precipitation

The majority of Santa Fe River discharge in most years is derived from snow melt runoff. As such, monitoring snow pack is a critical component to assessing and forecasting Santa Fe River water supply on an annual and seasonal basis. Although precipitation as rainfall has contributed significantly to reservoir storage on several occasions, and the rarity of these events preclude their incorporation in water supply planning scenarios, monitoring precipitation as rainfall is important for safe operation of the reservoirs.

In order to increase the quality and usefulness of precipitation data, we recommend that locations where precipitation as rainfall is currently being recorded be upgraded from manual measurements to automated logging with SCADA telemetry. In addition, the precipitation gages should be equipped to measure both snowfall and rain. The collected snowfall data will be used to complement snowfall already being collected by the NRCS at the snow pillow sites, while rainfall data will be used to compile an on-going record for identifying trends and future planning.

Reservoir Level

Reservoir level information is critical for proper management of the reservoirs, compliance with water-right permits, and for delivery of adequate treated water to City water customers. In the past, reservoir levels were determined by visual inspection of a staff gage located on the reservoir outlet tower using a telescope, and reported in 100th of feet. Reservoir level monitoring has since been upgraded to an automated system using an ultrasonic sensor with SCADA telemetry to transmit real-time measurements to the water treatment plant for logging and reporting; however, there are currently some problems with telemetry signals reaching the water treatment plant from the McClure reservoir. We recommend that the water utility install a SCADA repeater to ensure accurate transmittal of reservoi- level data to the water treatment plant.

Reservoir Bathymetry

The City’s water utility has conducted several bathymetric surveys of the reservoirs in order to assess changes in storage capacity over time. The most recent reservoir bathymetry study was conducted in 1993. Reservoir bathymetry studies should be continued in the future in order to protect reservoir capacity and ensure safe operation of water utility works. In absence of a catastrophic runoff/erosion event that is deemed to have deposited significant material in either of the reservoirs, a regular interval for bathymetric studies should be approximately every 20 years. In the event that significant material is deposited within a reservoir, then the water utility will conduct a bathymetric study at the earliest time afterward to asses impact to reservoir storage.

Maintain a High Quality of Water

Regularly monitor 10 critical parameters for water quality below the Nichols Reservoir and/or at the water treatment plant.

Critical parameters that require regular analysis for water quality include a total of 10 parameters, and monitoring will occur below the Nichols Reservoir or at the water treatment plant.

Total Organic Carbon (TOC) and Dissolved Organic Carbon (DOC)

TOC and DOC are important to water treatment operators because of the potential for organic carbon to form trihalomethanes (THMs) as a disinfection byproduct during chlorination. THMs are carcinogens and regulated by EPA. TOC and DOC are sampled once a month in raw water by the WTP below Nichols Reservoir as required by the EPA.

E. coli, Giardia and Cryptosporidium

E. coli, Giardia and Cryptosporidium in raw water have been sampled monthly by the WTP since April 2007 as required by the EPA Long Term 2 Enhanced Surface Water Treatment Rule (LT2ESWTR). Monthly samples are collected at the outlet from Nichols Reservoir and submitted to a laboratory, which will continue until March 2009. Results of the sampling will determine the level of treatment required at the City WTP. If the mean concentration is less than .075 oocyst/L, then minimal treatment will be required and the two-year monthly sampling cycle will be repeated six years later (in 2015). Results to date, show very low detections of cryptosporidium.

Temperature

Water temperature impacts the “metabolism, behavior and mortality of fish and other aquatic organisms” (NMED 2008). Continuous measurement of temperature is necessary to determine the maximum daily temperatures, the duration of excessive temperatures and the diurnal and seasonal fluctuations of temperature that affect aquatic life. New Mexico Water Quality Standards (20.6.4.121.B1) for temperature is less than 20 degrees centigrade for aquatic cold water fisheries.

Dissolved Oxygen (DO)

Cold water aquatic species, particularly embryos and larvae, are more sensitive to dissolved oxygen concentrations than warm water species. DO concentrations need to be at least 6 mg/L for healthy aquatic systems. Because DO is impacted by temperature and elevation, the percent saturation of DO is also important and it should approach 100%. Cold water can hold more oxygen than warm water.

pH

The water treatment plant and aquatic life are both sensitive to the pH of water. The treatment plan operators need to know the pH to adjust the alkalinity of the water to achieve good coagulation and produce stabilized water. The pH is measured continuously by the City WTP at the intake before treatment (out of Nichols Reservoir). NMED SWQ Bureau has also measured pH in Santa Fe River water in three locations, three times a year. The pH should remain between 6.6 and 8.8 (NMWQCC, 2007). Measured pH at the three sites in the Upper Watershed average 7.3, with a maximum observed at 8.7 in the fall at the inflow into McClure and a minimum of 6.1 measured several times in the spring at the wilderness boundary and at the inflow to McClure Reservoir. The low alkalinity of the water results in a lack of buffering capacity for the water which allows the pH to be unstable.

EC (Conductivity)

The specific conductance or electrical conductivity of water is an indicator of the total dissolved solids. It is a very inexpensive field check on water quality and could be used to indicate significant changes in water quality. EC has been recorded in the field by NMED SWQB at three sites, three times a year. EC measurements have ranged from 31 to 187 μmhos/cm in the Upper Watershed, less than the numeric criteria of 300 μmhos/cm or less (NMWQCC, 2007).

Turbidity

Turbidity is a principal physical characteristic of water and is an expression of the relative clarity of a liquid. It is caused by suspended matter or impurities that interfere with the clarity of the water. These impurities may include clay, silt, finely divided inorganic and organic matter, soluble colored organic compounds, and plankton and other microscopic organisms.

Clarity is important when producing drinking water for human consumption and in many manufacturing uses. Excessive turbidity, or cloudiness, in drinking water is aesthetically unappealing, and may also represent a health concern. Turbidity can provide food and shelter for pathogens. If not removed, turbidity can promote regrowth of pathogens in the distribution system, leading to waterborne disease outbreaks, which have caused significant cases of gastroenteritis throughout the United States and the world. Although turbidity is not a direct indicator of health risk, numerous studies show a strong relationship between removal of turbidity and removal of protozoa. (EPA 1999).

Alkalinity (Total Hydroxide, Carbonate, Bicarbonate)

Alkalinity is a measure of the ability of a solution to neutralize acids to the equivalence point of carbonate or bicarbonate. In effect, it is a measure of the buffering capacity of the water. Alkalinity is important to monitor for municipal water supplies because of its affect on the amount of chemicals needed to achieve coagulation and impact on the corrosion in distribution systems. Alkalinity is measured once a month by the City WTP below Nichols Reservoir.

PCBs

PCBs were detected in the outfall from Nichols Reservoir on May 3, 200,7 at concentrations totaling 0.235 μg/L, which is above the standard of .064 μg/L for domestic water supply and 0.014 μg/L for aquatic life and wildlife habitat. No other locations were sampled. We recommend that surface water be sampled for PCBs at the two locations above each reservoir to verify these results and determine if further assessment is necessary. If samples show no detection of PCBs, then no further sampling is recommended. If PCBs are detected, the NMED should be contacted to investigate the extent and source of contamination.

Enhanced Wildlife Habitat and Ecosystem Function

The first goal with habitat enhancement is to identify and define the species of interest within the project area for which further habitat assessment and enhancement activities will be carried out, and to define the optimum functioning capacity for the riparian and aquatic zones within the project area, which will be accomplished largely through the first round of ecological monitoring using Rapid Stream-Riparian Assessment (RSRA) methods. Based on results of ecological monitoring and evaluation of functional assessment of the riparian corridor, specific deficiencies in the riparian zone and in the stream course will be identified. The following is a list of six geomorphologically distinct riparian areas along the Santa Fe River within the upper watershed where ecological monitoring will be conducted:

  • Two reaches of the upstream of McClure reservoir
  • Three reaches downstream of McClure reservoir
  • One reach downstream of Nichols reservoir.

The Rapid Stream-Riparian Assessment (RSRA) utilizes a primarily qualitative assessment based on quantitative measurements. It focuses upon five functional components of the stream-riparian ecosystem that provide important benefits to humans and wildlife, and which, on public lands, are often the subject of government regulation and standards. These components are: 1) water quality and pollution, 2) stream channel and floodplain morphology and the ability of the system to limit erosion and withstand flooding without damage, 3) the presence of habitat for native fish and other aquatic species, 4) vegetation structure and composition, including the occurrence and relative dominance of exotic or non-native species, and 5) suitability as habitat for terrestrial wildlife, including threatened or endangered species. Within each of these areas, the RSRA evaluates between two and seven variables which reflect the overall function and health of the stream-riparian ecosystem (Stacey et al 2007).

To address the deficiencies, specific habitat enhancement recommendations will be developed and compiled in a Habitat Enhancement Plan (HEP). With input form the City’s partners and riparian and aquatic habitat experts, these recommendations will identify passive and active methods to affect measurable change in functioning capacity. Habitat enhancement activities in the riparian corridor and the stream course will be coordinated, as potential work in the stream course will necessitate removal or thinning of established vegetation along the banks of the river, modification of bank slope, and possible creation of new channel meanders which will require bank revegetation.

The HEP will consider methods that involve active work in the channel like installation of rock step and/or log plunge structures, riffles and pools, bank revetment, and induced meanders. More passive methods that may be effective in the channel involve operational changes in the way the City’s water utility can release water from McClure and Nichols reservoirs, Specifically, releases of larger pulses of water may mimic pre-dam snowmelt and high intensity short duration storm flows, which have the potential to create some beneficial stream bank erosion and other deposits that will enhance overall aquatic habitat features. The HEP will also evaluate methods to enhance riparian habitat, like removal of invasive species, thinning of existing vegetation, and additional plantings to control erosion and improve habitat in disturbed areas.

Any active channel and riparian work called for in the HEP will require a survey, hydrologic analysis, possibly engineering drawings, and permit approval from regulatory agencies including the USACE and NMED.

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