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| Triangle Area Water Supply Monitoring Project |
The Triangle Area Water Supply Monitoring Project was established to provide local governments with water-quality and streamflow data that could be used to protect and monitor the area's surface-water supplies. Specific goals of the Project are to:
- Supplement existing data on major ions, nutrients, and trace elements to enable determination of long-term trends;
- Examine differences in water quality among water supplies within the region, especially differences among smaller upland sources, large multipurpose reservoirs, and run-of-river supplies;
- Provide tributary loading and in-lake data for predictive modeling of Falls and Jordan Lakes; and
- Establish a data base for the presence of synthetic organic compounds in surface water in the region.
Implementation
The Project has been implemented in phases and is currently in phase VI. Each
phase has been marked by the development of an interlocal agreement in which
the objectives are re-evaluated and revised, if needed, and cost is allocated
to each participating local government or agency.
Phase VI
Objectives for Phase VI:
- Extend the existing water-quality database for major ions, nutrients, sediment, and trace elements to track spatial variations in water quality, loads to reservoirs, and long-term water-quality trends.
- Continue collection of water-quality data at tributary sites during high-flow events to increase the understanding of constituent concentrations and mass loading during extreme hydrologic conditions.
- Investigate the occurrence of mercury in water and sediment.
- Maintain a network of continuous streamflow gaging stations in the study area.
- Publish an analysis of water-quality trends for data collected through 2007.
Phase V
Objectives for Phase V:
- Extend the existing water-quality data base for major ions, nutrients, sediment, and trace elements through June 2007 to provide data necessary for determining spatial variation in water quality, loads to reservoirs, and for analysis of water-quality trends.
- Continue data collection at existing tributary sites during high-flow events.
- Investigate the occurrence of emerging water-quality contaminants, including selected pharmaceutical compounds, antibiotics, and other wastewater indicators, at seven sites near water-supply intakes.
- Maintain a network of continuous streamflow gaging stations in the study area.
- Increase public awareness and understanding of the Project and quality of water-supply sources in the region through periodic progress reports, press releases, presentations, and by maintaining a Project web site.
- Publish a report that includes analysis of water-quality trends for data collected through 2005.
Phase IV
Objectives for Phase IV:
- Continue monitoring for major ions, nutrients, and trace elements through June 2003 for study sites to provide data useful for determining spatial variation in water quality, loads to reservoirs, and for analysis of water-quality trends;
- Determine the presence of selected U.S. EPA regulated drinking-water contaminants in the region's surface water;
- Increase data collection to describe spatial variation in water quality among segments of Jordan Lake relevant to water treatment concerns;
- Add a streamflow gage and conduct water-quality sampling in the White Oak creek sub basin of Jordan Lake;
- Develop an integrated water-quality data base of data collected by municipal water and wastewater-treatment facilities in the study area and data collected by the USGS for this study;
- Increase public awareness and understanding of the Project and quality of water in the region through progress reports, press releases, and by maintaining a web site; and
- Maintain a system of continuous streamflow gaging stations in the study area.
Phase III--Recommendations for extending and modifying the program.
The Triangle Area Water Supply Monitoring Project has made additional significant progress toward its original goals. It has provided a solid basis for measuring long-term changes in water quality, and expanded our information about synthetic organic chemicals in the Triangle Area's water supplies. Much of this data will be of value to local utilities in meeting new monitoring requirements under the Safe Drinking Water Act and in developing strategies for protecting and treating local drinking water supplies.
Based on the first five years of monitoring data, sampling frequency may be reduced for major ions, nutrients, and trace metals without losing valuable statistical data. The Project Steering committee, composed of representatives from each participating local government, recommends the following specific changes to the Project:
- Streams: Sample physical properties, major ions and nutrients 6 times per year and trace metals 2 times per year at intake sites and other USGS stream sites (years 1,2,3, and 4)
- Lakes: Sample physical properties, major ions, nutrients, and chlorophyll a 4 times per year and trace metals 2 times per year. (years 1,2,3, and 4)
USGS would reduce major ions and nutrient monitoring at its sites from 12 to 4 times per year. The Committee believes, given the existing Project database, the proposed monitoring frequency and sites for Phase III will maintain statistical validity while freeing up resources for other monitoring.
- 13 DEM Sites: The remaining stream and reservoir sites in the network will be sampled by DEM. DEM will sample 13 sites 12 times per year for nutrients and less frequently for trace metals and major ions. (years 1,2,3, and 4)
- Collect and analyze samples once per year at 9 intake sites for selected organics. (years 1,2,3, and 4)
This expands the number of organic constituents measured at intake areas.
- Sample selected sites (5 sites) 2 times each during a storm event for major ions, nutrients, and trace metals (year 1)
During Phase II, the Project conducted special storm event monitoring at 6 sites and monitored one half of the remaining sites once during high flows. In year 1 Phase III, the Project will evaluate sites to determine where it needs additional high flow data. This data will enhance the Project's pollutant loading analysis.
- Discontinue all project monitoring at Falls Lake at Raleigh intake, NC 50, I-85, and NC 98; at Little Lick Creek, Knap of Reeds Creek, Ellerbe Creek, Swift Creek, and at Lake Benson. Discontinue all project monitoring at Jordan Lake at Bells Landing and the Smithfield site on the Neuse River.
The City of Raleigh and the Town of Smithfield are not participating in Phase III of the Project.
- Develop annual project summaries (year 1,2, and 3), an interpretive report. (year 4)
Phase II-- Recommendations for extending and modifying the program.
The Triangle Area Water Supply Monitoring Project has made substantial progress towards its original goals. It has provided a solid basis for measuring long-term changes in water quality, and expanded considerably our sparse information about synthetic organic chemicals in the triangle Area's water supplies. Much of this data will be of value to local utilities in meeting new monitoring requirements under the federal Safe Drinking Water Act.
Based on the first two years' data, several parameters and sampling locations may be dropped from the program without losing valuable information. Although no real surprises or water quality "problems" were revealed during the first two years, the program has identified one or more issues of interest for each locality. Some of these, such as the occasional presence of pesticides downstream of urban areas, merit more detailed follow-up study. As noted at the Project's beginning in 1988, additional years of data will be needed to detect statistically meaningful changes in other constituents.
The Project Steering Committee composed of representatives from each participating local government, recommends the following changes to the project:
- Extend the monitoring project for three more years (October 1991 - June 30, 1995).
This will further strengthen the statistical basis for measuring long-term changes in water quality, and will enable more detailed investigation of certain issues identified during the first two years of monitoring (See below).
- Maintain annual costs at no more than current amounts.
Local shares in Project costs are determined in proportion to the amount of water produced by each local entity as determined January 1, 1991.
- Maintain existing parametric coverage at existing locations except for the following changes to begin in Year 4 (October, 1991):
- Delete the analysis of volatile organic chemicals (VOCs) for the next three years, but maintain GC/FID screening for other synthetic organics.
The patterns of VOC occurrence detected during the first two years (primarily trihalomethanes produced during water and wastewater treatment) revealed neither surprises nor cause for concern regarding water supply quality. Virtually no other VOCs were detected. It may be advisable to check or confirm this pattern through additional VOCs monitoring some time in the future.
GC/FID screening provides a relatively inexpensive way to "keep and eye on" other synthetic organic chemicals that may be present from time to time. This analysis should be maintained.
- Delete routine pesticide analysis, but focus sampling and monitoring efforts on one geographic area in order to determine the source of pesticides which appeared downstream of urban areas during the first two years of monitoring.
The present program is not able to determine, for example, whether pesticides detected downstream of urban areas were the result of general urban runoff, or were flushed down the drain and discharged through wastewater treatment plants.
- Discontinue monitoring at the outflows of Lake Michie and Little River Reservoir.
Existing sites at the Lake Michie and Little River Reservoir water intakes will be maintained. The first two years' data indicate that there is no difference in water quality between these locations and sites immediately downstream. The outflow locations can be dropped with little risk of losing information.
- Conduct storm event monitoring for total nutrients, metal, pesticides, and other non-volatile organics at several major tributaries.
Storms are major loading events for the area's water supplies. Substantial amounts of pollutants are mobilized from non-point source runoff and resuspended bottom sediments during and immediately after storms. Substances that are not detectable during routine monitoring are often present at this time.
Phase I--Triangle Area Water Supply Monitoring Project
Objectives:
- Expand the sparse existing data base for synthetic organic chemicals to better determine their presence or absence in the region's waters; and, supplement the existing nutrient and trace metal data base for measuring long term trends in major water supplies. It is recognized that additional years of data will be needed to detect statistically meaningful changes in water quality.
- Provide a basis for measuring shorter term, but long-lasting, changes due to large scale management practices in the watersheds, such as the phosphate detergent ban, treatment plant upgrades, etc. The monitoring program will not be designed to detect short-term episodic events, such as temporary treatment plant failures or chemical spills.
- Document any overall spatial differences among water supplies within the region, especially differences between smaller upland sources (Cane Creek, University Lake, Little River), large multipurpose reservoirs (Falls and Jordan lakes), and run of river supplies (Neuse and Cape Fear Rivers).
- Provide additional tributary loading and in-lake data that can be used for predictive models of Falls and Jordan Reservoirs.
- Help determine the role of stream sediments (particulate matter) in transporting or removing synthetic organic chemicals in the water column.
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