Water Quality Impact Evaluations Using Projected Land Use Patterns

and

Non Point Source Pollution Education Program

for the

Upper Cape Fear River Basin

Report written by: Carol Patrick, Piedmont Triad Council of Governments

Date: June 30, 2002

Background

In 1998, the Piedmont Triad Council of Governments (PTCOG) received a 205(j) grant to evaluate the impact of land use patterns for watersheds that have a 303(d) listed stream in the Haw River sub-basin and the Randleman Lake sub-basin of the Upper Cape Fear River Basin. This project was conducted in conjunction with the Triangle J Council of Governments. The five counties that PTCOG evaluated watersheds in were: Alamance, Rockingham, Randolph, Guilford, and Caswell. The five watersheds selected were (see map below):

Ø Alamance County: Town Branch

Ø Rockingham County: Little Troublesome Creek

Ø Randolph County: Hasketts Creek

Ø Guilford County: Hickory Creek

Ø Caswell County: Stony Creek

A 303(d) listed stream was selected from each of these counties, with the exception of Caswell County, because no 303(d) listed streams were present. In Caswell, Stony Creek was selected because it is a high growth area. Land use data (current and projected), zoning and other data were gathered by PTCOG to determine what the present and future growth trends would be. PTCOG then worked with the local governments in educating their staff about the impact of increased growth on streams, particularly impaired streams.

Project Objectives

Provide a general evaluation of potential water quality impacts of long-term land use plans on five streams within PTCOG’s region (Region G).
Increase level of public awareness of project impacts of land use plans and alternative development scenarios on surface water quality.
Assist local governments’ efforts to develop strategies for improving impaired waters.

Methodology

Digital land use and zoning information was obtained from most municipalities for the project. However, some municipalities still do not have digital information available. Caswell County does not have zoning and their parcels are not digital yet; therefore, Caswell County numbers are estimates. Guilford County does not have digital parcels available yet; therefore, estimates were also used for this watershed. The impervious surface ratios and runoff rates were obtained from the Neuse River Basin Stormwater Model, Streamlines Newsletter (7/96), and local knowledge. The simple method was used for runoff rates. These numbers do not represent any one pollutant’s runoff rate. They are used just to give a rough estimate for the amount of runoff. The development of these watersheds ranges from low-density residential/agricultural to more urban developed watersheds. According to the Center for Watershed Protection, the level of water quality in a watershed will show signs of impact at as little as 10% imperviousness, and at 25% imperviousness the watershed may not be supporting its designated uses at all. The tables included in the report will be summaries; however, detailed tables are included in the appendix A.

Results

Town Branch in Graham (Alamance County)

Town Branch is a small stream that starts in the northwest portion of Graham and flows through the oldest part of town and eventually deposits into the Haw River just south of Hwy 54. The entire stream segment (3.6 miles) is on North Carolina’s 303(d) impaired stream list for fecal coliform bacteria. A Total Maximum Daily Load (TMDL) for fecal coliform bacteria has been developed and is currently under public review. Graham’s wastewater treatment plant discharges into Haw River and does not appear to be the source of the fecal problems. Town Branch also falls within the Jordan Lake watershed that is a nutrient sensitive watershed. The Jordan Lake Modeling Project results show that 74% of Graham’s nitrogen discharge flow makes it to Jordan Lake. However, the majority of the nutrient problems in the Haw River are from nonpoint sources (2/3rds).

The Town Branch watershed area is relatively small, 4.5 square miles or 2909 acres. This watershed area is already highly developed with few opportunities for new growth. The impervious coverage area in this watershed is 50% (see table 1). This level of impervious cover would indicate a non-supporting stream (Center For Watershed Protection, 1999). Of the current land uses present, 65% is residential, 24% is industrial, 8% is business and 3% is office and institution (see map 1). A growth management plan was developed by PTCOG for the City of Graham in 2000. Town Branch falls into the North and Central planning districts. The boundary between the North and Central planning districts is I40/I85. According to the plan, redevelopment is encouraged in these areas due to most of the land being developed. However, the Central planning district has more available land for development. Also, the City of Graham is not located within a water supply watershed and therefore doesn’t fall under any water supply watershed restrictions.

Town Branch - Development Scenarios

The Town Branch watershed has 50% impervious surface coverage. This yields 17,370 lbs/yr of pollution runoff (see table 1). If the recommendations of the growth management plan are followed and commercial strip development is discouraged, redevelopment is encouraged and open space is valued, then the impervious surface ratio will not change much. However, if low-density residential is converted to business or industrial, then the impervious surface ratio will increase significantly and the streams will likely have greater degradation, unless steps are taken to control the runoff (see table 2 and map 2).

Map 1: Current Zoning

Table 1: Town Branch Current Conditions

	% of		% Imperv	# Imperv	Runoff Rates	Total Runoff
Land Use	Total Acres	# of Acres	Surface	Acres	(lbs/ac/yr)	(lbs/yr)
Residential	65%	1883	33%	621	6.9	4265
Business	8%	243	80%	194	17.5	3399
Office & Institutional	3%	81	85%	69	16.9	1163
Industrial	24%	703	80%	562	15.2	8544

Total		2,909		1,446		17,371

% Impervious Area in Watershed = 50%

Map 2: Future Development Land Use

Table 2: Town Branch – Increase in Business Development

	% of		% Imperv	# Imperv	Runoff Rates	Total Runoff
	Total Acres	# of Acres	Surface	Acres	(lbs/ac/yr)	(lbs/yr)
Residential	51%	1483	28%	415	4.6	1910
Business	22%	643	85%	547	17	9291
Office & Institutional	3%	81	85%	69	16.9	1163
Industrial	24%	703	80%	548	15.2	8330

Total		2,910		1,579		20,694

% Impervious Area in Watershed = 54%

Town Branch – Education/Next Steps

PTCOG has been working with and educating the City of Graham staff on Phase II Stormwater rules, TMDLs and other water quality issues. PTCOG has received approval for a North Carolina 319 non-point source pollution grant for Town Branch that will involve developing an implementation plan for the Town Branch fecal coliform bacteria TMDL. The City of Graham is being proactive in determining the problems and finding the solutions. Also, this project would include installation of BMPs (Best Management Practices) to aid in reducing fecal coliform bacteria pollution. The possible BMPs include:

Ø Structural

o Constructed Wetlands

o Rain Gardens

o Buffers

Ø Non-Structural

o Pet ordinance

o Public education of pet waste

Any BMPs implemented by the 319 fecal coliform project will help reduce pollution overall, not just with fecal coliform. However, other BMPs that the city might consider are:

Ø Structural

o Wet Detention Basin

o Dry Detention Basin

o Wet Retention Basin

o Filter Strips

o Grassed Swales

Ø Non-Structural

o Parking Lot and Street Cleaning

o Catch Basin Cleaning

o Land-Use Control

§ Low-Density Development

§ Comprehensive Site Planning

§ Sanitary Waste Management

Little Troublesome Creek (Rockingham County)

Little Troublesome Creek originates in Reidsville and flows through the city and into the county until it deposits into the Haw River (8.3 miles). The watershed is roughly 12 square miles in size and has a mixture of farmland and urban landscape with an overall impervious coverage area of 35%. Although this is a more rural watershed with a lower impervious surface ratio, it is showing signs of stress. Another contributing factor is the main stem of Little Troublesome was channelized many years ago. This stream is on the 303(d) impairment list for fecal coliform bacteria, biological impairment and sediment. The fecal coliform bacteria impairment starts at the Reidsville WWTP and extends down to the Haw River. A fecal coliform bacteria TMDL has been written for Little Troublesome that calls for a 40% reduction of fecal coliform bacteria load from the stream. PTCOG working in conjunction with the City of Reidsville, has obtained a 319 to create an implementation plan for the TMDL. Also, the NC Wetland Restoration Program is currently developing a Local Watershed Plan for Little Troublesome Creek in conjunction with a stakeholder group and WECO (Watershed Education for Communities and Local Officials). Little Troublesome is also a part of the Jordan Lake watershed and is a nutrient sensitive watershed. According to the Jordan Lake model, only 42% of the nutrient load reaches Jordan Lake.

Little Troublesome Development Scenarios

Rockingham County is currently developing a comprehensive land use plan and is also developing an economic revitalization plan, 21^st Century Initiative Plan, to jump start their economy. So growth areas are uncertain. However, with the future I-73 corridor (currently US 29) and I-785 loop around Greensboro, future growth in this watershed is a reality. The question remains as to how that growth will be managed. It is most likely that growth will occur along the I-73 corridor; business, commercial, industrial and residential development growth will happen as a result of more traffic coming through that area. Currently, the majority of the watershed is agricultural (43%) or residential (27%) (see table 3). However, a quarter of the watershed is also industrial 24%. This contributes to the high runoff numbers. Even though it only represents 24% of the total area, it contributes 2/3^rd of the runoff.

Map 3: Current Zoning (Reidsville Only)

Table 3: Little Troublesome Current Conditions

			% Imperv	# Acres	Runoff Rates	Total Runoff
	% of Acres	# of Acres	Area	Imperv Area	(lbs/ac/yr)	(lbs/yr)
Agricultural	43%	3435	10%	343	1.8	618
Residential	27%	2117	28%	593	4.9	2,905
Business	6%	457	85%	388	18	6,987
Office & Institutional	1%	90	75%	68	14.4	973
Industrial	24%	1878	75%	1,409	14.4	20,283
Total		7,976		2,800		31,766

% Impervious Area in Watershed = 35%

If growth along the US 29 (future I-73) corridor is not managed, large parcels of farmland could be converted to industrial sites or business development. The total impervious surface coverage could increase significantly and the water quality degraded even more (see table 4).

Table 4: Little Troublesome Scenario 1: Increased Business and Industrial Development

			% Imperv	# Acres	Runoff Rates	Total Runoff