Final Recommendations
for
Protecting the Cane Creek Water Supply

Adopted by Orange Water and Sewer Authority Board of Directors
October 23, 1997

NOTE: This version does not include Appendices B and C of the Final Recommendations. These may be obtained in hard copy form from Ed Holland, Director of Planning and Development, at OWASA (e-mail eholland@owasa.org or telephone (919) 986-4421 ext. 215).

Introduction and Background

Orange Water and Sewer Authority (OWASA) owns and operates the Cane Creek Reservoir as one of two principle water supplies for the Towns of Carrboro and Chapel Hill, the University of North Carolina at Chapel Hill, UNC Hospitals, and portions of Orange County. The reservoir cost $20 million to build and was filled in 1989. Cane Creek is expected to provide water to the community through the twenty-first century.

In January 1994 the OWASA Board of Directors appointed a 22-member Watershed Advisory Committee to guide the Board in developing a management plan for ensuring the long term quality of the Cane Creek Reservoir. The Committee's charge included assistance to staff and Board in developing the scope of work for a consultant study; interaction with staff and consultants during the study; and finally, advising the Board on a preferred water supply protection strategy. The Committee was composed of a range of stakeholders, including property owners and watershed residents, water customers from Carrboro and Chapel Hill, professional experts from the University, elected officials from each governing jurisdiction, and OWASA Board members. A complete list of Committee members is attached as Appendix A.

In October 1994 the Board approved Committee-drafted goals, objectives, and a scope of work, and in June 1995 awarded a consulting contract to the Cadmus Group, Inc. Cadmus worked closely with the Committee and OWASA staff reviewing data, developing, refining, and modeling alternative management scenarios, and in August 1996 presented results in the Cane Creek Reservoir Watershed Study - Draft Report.

Findings indicated that future water quality objectives could be met through four different approaches that relied on varying degrees of open space preservation, large lot zoning, cluster development, regional stormwater ponds, and tributary subimpoundments. Each of the options theoretically offered the same water quality outcome, but differed substantially in its impact on watershed property owners, cost to OWASA ratepayers, uncertainty of meeting predicted results, and potential for unintended or irreversible results.

The Committee and the OWASA Board agreed to solicit additional community input before recommending a single preferred strategy. Accordingly, the Cadmus report was circulated to local elected officials, staff, and interested citizens; highlighted in newspaper articles; and presented at three public meetings, including one in Bingham Township in the watershed. Verbal and written comments were received from nearly 50 individuals. These were compiled by OWASA staff and reviewed by the Watershed Advisory Committee in March and April 1997. An additional management scenario emerged from this process and was evaluated by Tetra Tech, Inc. (successor contractors to the Cadmus Group) for compliance with previously established water quality goals.

On June 26, 1997 the OWASA Board adopted Provisional Recommendations for Protecting the Cane Creek Water Supply that incorporated efforts and comments compiled as of that date. The Provisional Recommendations were transmitted to the Carrboro Board of Aldermen and Chapel Hill Town Council to establish further consensus before submitting final recommendations to the Orange County Board of Commissioners. OWASA Board members made informational presentations to the Towns on August 25 and 26 and received their official comments on October 9.

Comments from the Towns have been incorporated, as appropriate, into the text of these Final Recommendations and are included in full at the end of Appendix C.

Orange County staff plan to prepare a report for the Board of Commissioners in December, 1997. Final action by the Commissioners on proposed ordinance changes is anticipated in August, 1998 after the County conducts public meetings and a joint public hearing of the Commissioners and Planning Board.

Guiding Principles

Long-standing water supply principles emphasize the importance of high quality source water. OWASA's own Water Supply Protection Policy expresses a commitment to high quality drinking water through a combination of source water protection and treatment technology.

The overall goal developed by the Watershed Advisory Committee and adopted by the OWASA Board was to manage the Cane Creek Reservoir to meet or exceed all applicable state and federal standards and to ensure its excellent water quality and long term viability as a public water supply source. This goal was characterized by four water quality and two non-water quality objectives. The most important was minimizing risks to public health, but of the non-water quality objectives, both the Committee and Board considered minimizing impacts on County residents who are not OWASA customers to be more important than minimizing rate increases to OWASA customers, and nearly as important as the public health objective. These objectives established benchmarks against which alternative management scenarios were evaluated and measured by Cadmus.

Additional principles and core values that underlie the recommendations presented in this report are noted below. Virtually all are related to the long period of time during which Cane Creek is expected to serve the community.

• The Cane Creek Reservoir is a valuable resource in which the people of Carrboro and Chapel Hill have invested more than $20 million. It is essential to protect this investment for the next 100 years or more.

• OWASA and other water providers are responsible for making decisions today and for managing resources for a future too distant to see with clarity. Sound management requires making these decisions with care and caution in order to sustain as many options as possible for future generations.

• Water quality problems typically develop over periods of years or decades and may require years or decades to resolve. Even though Cane Creek water quality is in compliance with current State and federal standards, actions are needed today in advance of environmental and regulatory conditions of tomorrow. Important lessons exist in the pro-active water supply protection decisions made more than a century ago by cities such as New York, Boston, Portland, Oregon, and Portland, Maine.

• As a water supplier, OWASA acknowledges a preference for non-structural protection strategies. Open space preservation and land use management through acquisition, zoning, and development controls is a practice with widespread support in the water industry and is preferable to technological methods, such as stormwater detention, tributary subimpoundments, and other engineered solutions, with unproved or inconsistent performance records.

• (Comment: It is noted that this institutional preference, which somewhat conflicts with efforts to minimize effects on watershed residents, was not shared unanimously by the Cane Creek Watershed Advisory Committee.)

• Community input, stakeholder equity, and effective partnerships are essential. OWASA is committed to applying to Cane Creek the valuable technical and political experience gained during the 1989-91 University Lake protection efforts.

Present Water Quality

Water quality in Cane Creek is generally good and in compliance with applicable regulatory standards, but it is not pristine. As in University Lake and other Piedmont reservoirs, Cane Creek is enriched by nutrients that contribute to a range of conditions that may compromise both public health and aesthetic objectives.

Cadmus conducted an in-depth review of current management practices and conservation plans for the five active dairy farms in the watershed. Findings and predictive analyses revealed a high degree of compliance with recommended agricultural practices for cropland, pastureland, and animal waste management. Inspection of recent and ongoing pesticides data from the reservoir and tributaries revealed occasional traces of agricultural herbicides. On the few occasions when these were detected in the reservoir itself, they were at levels more than 10 times lower than pesticide standards for treated drinking water.

Modeling analyses indicate that development regulations and practices currently in place are not sufficient to prevent future deterioration from new development.

Overall findings and management options are summarized below. Details are available in the August 1996 Cadmus report.

Major Findings:

• Existing water quality is acceptable, but not pristine.

• The most significant water quality problems are associated with nutrients and algal blooms. Cadmus characterized these as representing a high risk to attaining the Cane Creek objectives.

• Low levels of dissolved oxygen in bottom waters during the summer months increase the concentration of naturally occurring iron and manganese, which create taste and staining problems unless removed at the treatment plant. Other compounds associated with high nutrient and low dissolved oxygen conditions can also cause objectionable tastes and odors in the treated water. These conditions are considered to be a high risk to attaining the aesthetic water quality objectives for Cane Creek.

• Total organic carbon (TOC) concentrations, an indicator of potentially harmful disinfection by-products formed during chlorination, are similarly considered to be a high risk condition. Cadmus' modeling indicated that TOC levels are not likely to change, regardless of management strategy.

• Based on current knowledge and monitoring data, there appears to be little risk from chemical pesticides and synthetic organic chemicals (SOCs).

• Risks from microbial pathogens, such as Giardia and Cryptosporidium, are in the low to moderate range and are expected to remain low if animal waste practices and OWASA's treatment plant operation are sustained at their current, high levels of performance.

• Sediment delivery to the reservoir reflects generally good land management practices and is within an acceptable range. Sedimentation is not expected to reduce water storage capacity if accumulation rates remain in the present range.

• Cane Creek's fish population is acceptable, but could be improved through independent fishery management programs.

• Aquatic weeds are not a current problem, but continued oversight is needed.

Management Options:

No single management option can meet all of the objectives; therefore, a combination of methods is needed:

• Modifications to the Orange County Zoning Ordinance - Orange County's watershed protection requirements are among the most stringent in North Carolina, but certain modifications are needed to manage degradation due to future development.

• Further evaluation of tributary detention by OWASA.

Additional steps recommended include:

• OWASA acquisition of nearly 1300 additional acres of critical land to help prevent future contamination.

• Modification of the Cane Creek water intake structure to allow selective withdrawal of higher quality water.

• Further evaluation of cost-effective water treatment options, such as pre-oxidation with chlorine dioxide, that may reduce the production of disinfection byproducts.

• Discussion with Alamance County officials their consideration of re-zoning the Alamance portion of the watershed.

Some options have been eliminated from further consideration:

• In-lake management techniques, such as mechanical de-stratification, bottom water aeration, alum-copper sulfate application, or biomanipulation, are not recommended.

State and Local Water Supply Protection

The North Carolina Environmental Management Commission (EMC) requires local counties and municipalities to enact baseline land use regulations for water supply watersheds within their jurisdictions. Communities may adopt stricter standards if desired.

Both Alamance and Orange Counties are in compliance with EMC regulations for the Cane Creek watershed. The one-acre minimum lot size required by Alamance County complies with the EMC's basic standard. By contrast, Orange County's water supply requirements are among the most stringent in the state. These are codified in Article 6.23, Extra Requirements for Watershed Protection Overlay Districts, of the Orange County Zoning Ordinance. Highlights include:

• A maximum allowable density of 1 dwelling unit per 2 acres throughout the watershed. Impervious surfaces are generally limited to 6 percent. Non-residential development is limited to 12 percent imperviousness, but no more than 139 of the 18,500+ Orange County acres in the watershed may be developed for non-residential purposes.

• Preference for non-structural stormwater controls that rely on buffers, natural vegetation, and infiltration. Structural controls, such as detention ponds, are allowed, but may not be used to qualify for density or impervious surface waivers. Any such devices are subject to strict performance requirements, including the posting of maintenance agreements, security bonds, and cash deposits.

• Buffer requirements are in place for the reservoir shoreline and along all perennial and intermittent streams. Buffers must remain in natural vegetation and may only be used for a limited set of restricted activities.

• Clustering of residential lots is allowed throughout the watershed with no prescriptive minimum lot size. Additionally, Orange County promotes its innovative Flexible Development Standards for Preserving Rural Character.

• Water supply and wastewater systems are limited to individual wells and on-site septic systems. Neither community water nor wastewater systems are allowed in the watershed.

Adequacy of Existing Programs

The Cadmus Group used Cane Creek field data to customize and calibrate water quality models to predict the results of future development and management scenarios. Water quality is predicted to deteriorate substantially as residential development exceeds 25 percent buildout. The reservoir already exhibits nuisance algae that cause taste and odor problems in treated water. These are often dominated by species that release harmful toxins under more extreme conditions. Algal blooms are predicted to quadruple in frequency, to more than 30 percent of the summer months, as development approaches 100 percent buildout.

Significantly, such a degree of degradation is predicted to result from future activities that comply with current regulations. As noted, Cadmus determined that these conditions could be avoided through different combinations of open space preservation, land acquisition, large lot zoning, cluster development, regional stormwater ponds, and tributary subimpoundments.

The recommendations presented below are the cumulative result of these technical analyses, community input, and Committee discussion. They attempt to provide a balance between water quality and stakeholder equity objectives outlined earlier. (Please see the Executive Summary of the August, 1996 Cadmus Report attached as Appendix B.)

Recommended Changes to Local Regulations

Under the recommended requirement, minimum lot sizes in the Cane Creek watershed would be the same as currently specified for University Lake; that is, 5-acre minimum, except for parcels recorded as of June 26, 1997, which could first be subdivided into as many as five 2-acre lots. Any additional lots created from the parent tract would have to be at least 5 acres. Existing parcels of less than 12 acres would be unaffected, because they could be subdivided into no more than five lots under either the proposed "5 and 2" zoning or under existing 2-acre zoning.

(Comment: More than 70 percent of the 1,050 existing parcels in the Orange County portion of the watershed are less than 12 acres in size. These properties, which constitute less than 20 percent of the watershed area, would not be affected by the new large lot requirements. Please see Table 1.)

Creative Open Space Design (Clustering)

As an alternative to mandatory large-lot development, property owners could choose a more flexible approach by locating dwelling units on smaller lots and reserving a portion of the tract as permanent open space. Existing forested or agricultural land could remain in those uses as part or all of the designated open space.

It is recommended that such development continue to be promoted under Orange County's Flexible Development Standards with a required open space reservation of 50 percent, allowable density of 2 acres per dwelling unit (based on total tract size and subject to suitability for septic systems), and a minimum actual lot size of 1 acre. Development opportunities on a hypothetical 55-acre parcel are illustrated for existing 2-acre zoning and compared to large lot and open space options in Figures 1 through 3.

Although the availability of central water or sewer utilities is recognized as an important factor in the viability of clustering, there is substantial concern about the reliability of subsurface and spray irrigation wastewater technology. At this time OWASA does not recommend these methods be allowed for community scale applications in the Cane Creek watershed, even if operated and maintained by OWASA. OWASA may choose to revisit this issue sometime in the future through an open, public process.

Table 1. Land Parcel Size in Cane Creek Watershed

NOTES: This table includes Orange County data only, and represents approximately 80 percent of the Cane Creek watershed area. Not included are: OWASA-owned property, Alamance County parcels, and a limited number of Bingham Township (Orange County) parcels located along the northern township border, or boundary parcels with significant area outside the watershed. Information was extracted from 1995 Orange County land parcel data. (OWASA analysis updated 9/30/97.)

Figure 1. Existing Zoning

Figure 2. Large Lots

Figure 3. Creative Open Space