Pennichuck Water Works Watershed Management Plan

Prepared for: Pennichuck Water Works Corporation 4 Water Street Nashua, NH 03060

Prepared by: Comprehensive Environmental Inc. 21 Depot Street Merrimack, NH 03054

August 1998 Table of Contents

Section Page Number

Executive Summary

1.0 Introduction 1.1 Watershed Characteristics ...... 1-1 1.2 Water Quality ...... 1-2 1.3 Hydrologic and Phosphorus Budgets ...... 1-2 1.4 Identification of Pollution Sources...... 1-2 1.5 Protective Measures ...... 1-3 1.6 Buffer Zones...... 1-3 1.7 Buildout Analysis...... 1-3 1.8 Recommendations ...... 1-3

2.0 Watershed Characteristics 2.1 Water Supply...... 2-1 2.2 Base Flow/Surface Flow ...... 2-2 2.3 Climate ...... 2-4 2.4 Land Uses...... 2-4 2.5 Geology & Soils ...... 2-4 2.6 Ponds and Channel Characteristics ...... 2-5

3.0 Water Quality 3.1 Introduction ...... 3-1 3.2 Regulatory Background...... 3-1 3.3 Watershed Water Quality ...... 3-3

4.0 Hydrology and Nutrient Loading 4.1 Hydrology...... 4-2 4.2 Nutrient Analysis...... 4-3

5.0 Pollution Sources 5.1 The Pollutants...... 5-1 5.2 Pollution Sources...... 5-2

6.0 Existing Protection Measures 6.1 Regulatory Protection...... 6-1 6.2 Town Wide Land Use Controls...... 6-3 6.3 Land Ownership ...... 6-15 6.4 Pennichuck Water Works...... 6-15 6.5 Town Ownership ...... 6-16 6.6 Other Protective Measures ...... 6-17

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7.0 Buffer Zones 7.1 What is a Buffer?...... 7-1 7.2 Buffer Zones (Stages)...... 7-2 7.3 Buffer Widths ...... 7-2 7.4 Buffer Criteria ...... 7-3

8.0 Buildout Analysis

9.0 Recommendations 9.1 Findings ...... 9-1 9.2 Recommended Actions...... 9-7

Figure Title On Page or Follows Page

Figure 2-1. Simplified Watershed...... 2-1 Figure 2-2. Chain Pond Schematic of Pennichuck Water Supply System ...... 2-2 Figure 2-3. Aerial View of Typical Watershed Boundaries ...... 2-2 Figure 2-4. Basemap of Watershed...... 2-2 Figure 2-5. Simplified Groundwater Baseflow Diagram...... 2-3 Figure 2-6. Land Use Map...... 2-4 Figure 3-1. Sampling Locations...... 3-4 Figure 3-2. Results of 1996 Fecal Coliform Analysis ...... 3-4 Figure 3-3. Historical Phosphorus Levels...... 3-4 Figure 4-1. Typical Hydrologic Cycle...... 4-2 Figure 4-2. Percent Hydrologic Contribution ...... 4-2 Figure 4-3. Subwatershed Delineation...... 4-2 Figure 4-4. Percent Phosphorus Contribution...... 4-4 Figure 4-5. Land Use Map...... 4-6 Figure 5-1. Potential Pollution Sources ...... 5-4 Figure 5-2. RCRA Sites ...... 5-4 Figure 5-3. Sewered Roads...... 5-6 Figure 6-1. Zoning Map...... 6-2 Figure 6-2. Protected Lands...... 6-16 Figure 7-1. Three Zone Buffer...... 7-2 Figure 8-1. Buildout Scenario...... 8-2 Figure 9-1. Commercial Parking Lot Using Infiltration Methods ...... 9-9 Figure 9-2. Cluster Housing...... 9-10

Tables Title On Page or Follows Page

Table 2-1. Pond Characteristics ...... 2-2 Table 2-2. Subwatershed Characteristics...... 2-2 Table 2-3. General Characteristics...... 2-4 Table 2-4. Summary of Effects of Watershed Characteristics on Water Quality...... 2-5 Table 3-1. NHDES Drinking Water Standards Compared to Pennichuck Finished Water...... 3-2

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Table 3-2. NHDES Class A Surface Water Quality Standards Compared to Pennichuck Raw Water...... 3-4 Table 3-3. Useful Watershed Water Quality Parameters and Their Meaning ...... 3-4 Table 4-1. Purpose of Hydrologic / Nutrient Budgets ...... 4-1 Table 4-2. Frequency Analysis of 54-year Period of Precipitation ...... 4-3 Table 4-3. Comparison of Hydrologic and Phosphorus Contributions by Subwatershed ...... 4-4 Table 4-4. Eutromod Modeling Parameters...... 4-6 Table 4-5. Land Use Areas within the Watershed (acres) ...... 4-6 Table 4-6. Phosphorus Loadings by Land Use for the Pennichuck Watershed...... 4-6 Table 4-7. Modeled In-pond Phosphorus Concentrations and Parameters for Pennichuck Water Supply System ...... 4-8 Table 4-8. Comparison of Estimated Phosphorus Levels (with and without detention) to Average Phosphorus Data for 1996...... 4-8 Table 4-9. In-pond Concentrations and Parameters for Phosphorus Reduction In the Pennichuck Water Supply System...... 4-9 Table 5-1. Remediation vs. Prevention Measures for the Pennichuck Watershed ...... 5-5 Table 6-1. Zoning Designations ...... 6-4 Table 7-1. Comparison of Required Setbacks ...... 7-2 Table 7-2. Summary of Various Filter Strip Studies ...... 7-4 Table 7-3. Buffer Zone Calculation Methods...... 7-4 Table 8-1. Percent Phosphorus Contribution by Subwatershed for Buildout Conditions ...... 8-2 Table 8-2. Total Phosphorus Loadings from Buildout Scenarios...... 8-2 Table 8-3. In-pond Concentrations for Buildout Scenarios...... 8-3 Table 9-1. Top 10 Problems in Pennichuck Watershed...... 9-1 Table 9-2. Pennichuck Watershed Imperviousness ...... 9-2 Table 9-3. Methods to Reduce Future Imperviousness of the Pennichuck Watershed ...... 9-7 Table 9-4. Buffer Zone Requirements ...... 9-8 Table 9-4. Remedial Measures Priority Subwatersheds ...... 9-13 Table 9-5. Recommended Practices to Prevent Stormwater Pollution from Service Stations/Auto Repair Areas...... 9-14

Appendices

A. Soils Map and Legend B. Historical Sampling Data and Location Map C. 1996 Sampling Data D. Hydrologic Analysis E. Specific Factors Applied for Phosphorus Loading F. Database Search and File Review Sites G. Buildout Phosphorus Loadings H. Model Bylaws I. Cohen Bill J. References K. Acknowledgements

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Water suppliers like Pennichuck have been impacted by this growth. Water Works Corporation are As houses, stores, industries and regulated under the Safe Drinking parking lots replace forest and Water Act and Amendments of 1996. farmland, more and more impervious Future regulations under this act are area is created. This impervious area expected to call for increased prevents natural recharge to treatment for water systems on poor groundwater from occurring, instead source waters, conversely, systems on forcing it to run overland to the high quality, protected source waters nearest stream channel in the form of are believed to have a high level of stormwater. public health protection. In addition to more future regulatory constraints, As Southern New Hampshire While most people systems with poor source water develops, industries, retail businesses, in the communities quality also tend to have problems and subdivisions create more from off-taste and odors caused by impervious area and typically pipe the in the watershed the poor source water quality. To increased surface water runoff offsite, are aware of the address these issues, Pennichuck usually to the nearest stream or impact that the Water Works Corporation created this channel. Over time, this has greatly Watershed Management Plan. increased the intensity and force of tremendous stormwater flows while decreasing growth in Southern The plan is built on an approach that groundwater recharge. The decrease New Hampshire divides the watershed into in groundwater recharge is manageable units called particularly problematic since it has had on traffic, subwatersheds. The foundation of the ultimately reduces “baseflow”. fewer are aware of plan is an analysis of watershed hydrology and pollutant loading by Baseflow is the groundwater the impact that it subwatershed. This allowed a critical discharge into streams that occurs has had on water comparison of how much each during dry weather and droughts. resources. subwatershed produces in quantity of Thus, the same amount of water and in quantity of pollutants. precipitation falling on the watershed This comparison then allowed now leaves the watershed at a high recommendations to focus on either rate in stormwater flow instead of prevention or remediation depending recharging groundwater for a slow on whether the subwatershed is one release. This ultimately damages which currently produces large both surface water and groundwater quantities of clean water, or whether resources. Ultimately the most it is more highly developed and significant impacts on water resources currently produces poor quality input include to the system. 1) reduced groundwater recharge that ultimately may result in While most people in the long-term declining communities in the watershed groundwater levels and impacts (Nashua, Hollis, Milford, Amherst, on private wells and public and Merrimack) are aware of the wells; and impact that the tremendous growth in 2) increased stormwater flows Southern New Hampshire has had on loaded with pollutants that traffic, fewer are aware of the impact impact streams and ponds in that it has had on water resources. the watershed that may Both surface water and groundwater eventually pose a public health Page 1 Executive Summary Executive Summary

threat and that now impact groundwater recharge and protection aquatic habitat, recreation and of streams and ponds in the the aesthetic resources of the watershed. Some of the watershed. recommendations in the plan include:

• The use of buffer zones and The effects on groundwater are buffer strips wherever possible by largely one of loss of recharge, community Planning Boards and although there are also impacts from Conservation Commissions; industrial sites that directly pollute groundwater through illegal discharge • The reduction in impervious or dumping. Surface water resources cover in new and/or modified are more indirectly but nonetheless developments, with increased strongly impacted. Stormwater groundwater recharge wherever pollutants include petroleum possible; hydrocarbons (oil and grease), toxic heavy metals, bacteria, viruses and • The use of setbacks for streams from livestock feeding and other A call to action is other microbiological organisms, and nutrients (phosphorus and nitrogen). activities potentially detrimental needed in all of From the standpoint of water supply, to water quality; and the watershed the most serious of these pollutants • The recommendation that towns to reduce are the microbiologicals, which pose developers in each of the towns a direct health threat, and nutrients. be required to provide control of the impact of post-development runoff so that it existing Nutrients provide an indirect impact does not exceed pre-development development and on water resources, particularly conditions. phosphorus, by encouraging aquatic to prevent future plant growth. Although this may Many of the recommendations focus negative impacts. seem beneficial at first blush, an on either prevention of impacts overabundance of aquatic vegetation through methods such as buffer strips and algae results in bloom and die-off and protected lands or remediation of conditions that can quickly clog existing pollution problems through waterways in an unsightly, odorous the use of Best Management Practices problem. This phenomenon is called such as infiltration basins and other “eutrophication” and it is happening water quality improvement controls. already in the chain pond system used by Pennichuck Water Works. The recommendations are summarized in the following table. The threats described above affect everyone in the watershed, whether or not Pennichuck supplies their water. A call to action is needed in all of the watershed towns to reduce the impact of existing development and to prevent future negative impacts. The recommendations of the report focus on the things that can be done by Pennichuck Water Works or by communities in the watershed. There is a common goal of increasing Page 2 Executive Summary

Pennichuck Watershed Management Plan Summary of Recommendations

Top 10 Problems Recommended Actions

1. Storm Water Reduce existing and future imperviousness Increased amount and poor quality of • Require that post-development runoff equal predevelopment runoff. storm water flows. This problem also • Minimize parking lot impacts using permeable dividers, street buffer strips and modified has led to a loss of baseflow and stream landscaping. channel erosion that further results in • Reduce transportation impacts of subdivisions by using skinny streets with grass swales declining water quality. • Use onsite infiltration whenever possible, including recharge of roof leaders and other drainage instead of connection with the existing or new storm drain systems. • Use clearing and grading plans that minimize site disturbance, require grading plans, erosion control plans and inspect progress during construction. • Minimize lawn sizes, encourage the use of native species for landscaping wherever possible and leave native vegetation in place as a buffer. 2. Minimal Protective Zones Require buffer zones around sensitive water resources and wetlands. Use a general guideline The ponds and tributary streams and of a 400-foot buffer around the chain ponds unless all runoff can be infiltrated or otherwise wetlands have little protection from treated. Use a general guideline of 200-feet around tributaries to the ponds. In some cases, storm water impacts. Future such as steep slopes, a greater buffer may be needed, while in other flat areas and with development is likely to further increase significant protective measures, a lesser buffer width may be suitable. Buffers should be the amount of poor quality storm water recorded on official maps and protected through perpetual conservation easements or flows. restrictions as well as signage. They also need to be protected from channeled flow. 3. Pond Eutrophication Determine sediment depths in each of the ponds and dredge as needed to provide The Pennichuck ponds are filling in sedimentation capacity. This capacity will help protect the water supply and other downstream rapidly. This will further exacerbate resources from development impacts. water quality and quantity problems. 4. Transportation Impacts. Work with Public Works Departments and the state Department of Transportation to avoid Transportation facilities in the watershed direct piping of runoff to streams and instead use infiltration technologies such as grassed are widespread and have major impacts swales and leaching catch basins. Work with watershed Fire Departments to address spill on water quality. issues. Develop a monitored demonstration roadway for comparison to an old style roadway. 5. Agricultural Impacts. • Provide education materials for agricultural landowners. Livestock using tributary streams for • Request buffer strips or zones from livestock concentrations. watering may result in the introduction • Purchase conservation easements where needed to protect from direct stream channel of undesirable contaminants. encroachment by livestock. 6. Hot Spots of Pollution Sources. Use infiltration controls at specific locations within the watershed where problems have been Multiple “hot spots” in the watershed identified. Follow up on status of all hazardous waste sites in the watershed and request action pose chemical risks to the water supply timetables. Provide special educational materials to service stations, car dealerships and and may threaten biological activity that automotive or other repair shops because of their potential to create major water quality normally cleanses water quality. impacts. 7. Technical Education Needed. • Hold a technical transfer workshop for Conservation Commissions, Planning Board There is a general lack of understanding members, Public Works staff, site developers and engineers. of watershed protection principles among regulatory, planning, public works and engineering. 8. Public Education Needed. • Develop an educational questionnaire to gauge the level of understanding within the There is a general lack of understanding watershed communities both before and after the education program. of watershed protection principles • Develop a school age public education program for watershed schools. among the watershed businesses and residents. 9. Regulatory Authority Lacking Modify watershed regulations or develop cooperative agreements with watershed towns. Pennichuck Water Works Corporation lacks up to date regulatory authority within the water supply. 10. Comprehensive Database Needed. • Measure steam channels and imperviousness annually. The available database is lacking. • Conduct periodic sediment depth sampling of ponds. • Conduct storm water monitoring of demonstration projects. • Conduct a one-year intensive monitoring program for dry and wet weather water quality Page 3 – Executive Summary 1.0 Introduction

Pennichuck Water Works supplies the 4. develop water and pollutant Section Contents City of Nashua and several other budgets to identify water 1.1 Watershed Characteristics-- 1-1 communities with a filtered water quality goals 1.2 Water Quality ------1-2 supply that meets all state and federal 5. identify and assess existing and 1.3 Hydrologic and Phosphorus water quality standards. However, potential sources of pollution; Budgets------1-2 future federally mandated water 6. identify and analyze existing 1.4 Identification of Pollution quality standards are expected to call protection measures; Sources ------1-2 for higher treatment standards in 7. determine the impacts of 1.5 Protective Measures------1-3 1.6 Buffer Zones------1-3 proportion to the raw water quality of buildout on the water supply; 1.7 Buildout Analysis------1-3 the source. It is thus likely that water 8. prepare the watershed 1.8 Recommendations------1-3 systems with better quality raw water protection program that sources will need less treatment while satisfies the objectives and the those with poor quality sources will identified water quality goals. need greater (and more expensive) treatment. This means that 1.1 Watershed conventionally filtered systems like Pennichuck may have to add Characteristics additional treatment if their raw water The Pennichuck watershed lies in five quality deteriorates. This can lead to Southern New Hampshire towns expensive capital and operation costs including Nashua, Merrimack, to meet these standards. Amherst, Milford, and Hollis. This

watershed supplies the Water systems that protect and chain ponds with improve raw water quality through surface flow (runoff) Conventionally filtered watershed protection will be better and baseflow able to protect public health and to systems like Pennichuck (groundwater). As the minimize both capital and annual towns within the may have to add operation costs in the future. watershed develop, additional treatment if their the amount of surface The Pennichuck Water Works raw water quality flow will increase, Watershed Study was developed with carrying with it land deteriorates. two objectives: surface pollutants.

Meanwhile the 1. to improve public health baseflow portion may decrease. protection and

2. reduce future treatment The type of land use and soils within expenditures. each community affects the amount of

surface flow and the amount of The basic steps in developing the pollution reaching the ponds. program included: Therefore, physical characteristics

such as hydrology (how much water is 1. develop objectives and a study contributed to the water supply by plan; different portions of the watershed), 2. characterize the watershed; soil types, and land uses in these 3. assess water quality compared to towns play an important role in the current surface water supply water quality of the ponds. These standards; relationships are discussed further in Section 2.0.

Page 1- 1 Pennichuck Water Works Watershed Management Plan 1.0 Introduction

For this study, the Pennichuck information was used to determine the watershed was delineated using total amount of water entering the topographic data and local storm drain water supply from each of the 10 maps to define the area draining into subwatersheds. Subwatersheds were the water supply. This watershed was then prioritized by the percent of their then broken down into 10 smaller runoff contribution to the water supply watersheds (subwatersheds) so areas to determine whic h areas contributed of the watershed could be compared to the largest quantities of water. This is one another to identify areas needing discussed in more detail in Section more attention. Section 2.0 explains 4.0. these characteristics in more detail. Phosphorus is also important to the 1.2 Water Quality water quality of the system. High levels of this nutrient can lead to The water quality of the ponds was excess algae and plant growth, which assessed to determine compliance with in turn can affect the systems’ State and Federal drinking water compliance with drinking water regulations that are regulations and can also cause taste designed to protect the and odor problems. To address this, a Calculated pollutant loads public health. Since there theoretical model of nutrient were used to identify the was limited historical data, (phosphorus) loading was also additional limited sampling developed for Pennichuck watershed subwatersheds that are the was conducted and a to determine which areas of the greatest threat to water baseline sampling program watershed were contributing the quality. was developed to obtain highest levels of phosphorus. additional information. Eutromod Watershed and Lake Modeling Software (Reckhow, 1990) Parameters tested include pH, was used for this analysis. This model conductivity, temperature, dissolved uses the hydrologic budget, land use, oxygen, turbidity, flow, fecal and soils data to estimate theoretical coliform, ammonia nitrogen, nitrate loadings to the water supply. These nitrogen, Total Kjeldahl nitrogen, and theoretical pollutant loads were used total phosphorus. Discussion of these to determine subwatersheds that are parameters and results of the sampling the greatest threat to water quality. are included in Section 3.0. More detail on both these analyses is included in Section 4.0. 1.3 Hydrologic and Phosphorus 1.4 Identification of Budgets Pollution Sources To identify pollution sources, a As discussed above, hydrology plays database search was conducted and an important role in determining the New Hampshire Department of water quality of a water system. In this Environmental Services (NHDES) study, precipitation data and data from files on sites and spills were reviewed. the United States Geological Survey A field review was also conducted. (USGS) were reviewed to define Pollution sources were then mapped to typical runoff flows for the average evaluate their threat to the water year in the Nashua area. This supply. Potential pollution sources Page 1- 2 Pennichuck Water Works Watershed Management Plan 1.0 Introduction included landfills, junkyards, zoning map. The buildout scenarios underground storage tanks, hazardous were modeled to determine the waste generators, Superfund sites, phosphorus impacts to the ponds releases of hazardous waste materials, should full development occur. This oil/gas spill sites, and discharge provides a “worst case” phosphorus permits. More detail on the pollution loading to the ponds. The buildout sources found and their impacts to analysis can be found in Section 8.0. Pennichuck watershed is included in Section 5.0. 1.8 Recommendations 1.5 Protective Based on the data collection and analysis efforts in this study, Measures recommendations were developed to provide Pennichuck with information The New Hampshire Department of on additional needed protection in the Environmental Services and local watershed. towns have regulations dealing with the protection of water supplies. Most towns also have overla y protection zones and new development bylaws Steps in the Development of a that may assist water quality Watershed Protection Plan protection. These were reviewed to 1. Develop objectives and a study plan. identify the existing level of 2. Review and evaluate watershed protection and to avoid duplication of characteristics. efforts. 3. Compare water quality to standards. Land ownership by Pennichuck Water 4. Identify water quality goals by Works and each of the Town’s developing hydrologic and nutrient Conservation Commissions were budgets. mapped since they may also offer a 5. Identify pollution sources. significant level of protection by 6. Evaluate existing protective remaining undeveloped. Section 6.0 measures. discusses in detail the regulations, 7. Estimate impacts of future protective practices, and protected development. lands in each of the towns. 8. Develop recommendations for meeting the objectives.

1.6 Buffer Zones Buffer zones were evaluated as a BMP for all areas of the Pennichuck Water Works water supply watershed. A detailed evaluation of buffer zones is included in Section 7.0.

1.7 Buildout Analysis A buildout scenario mimics the conditions that would exist if the towns developed to their highest potential in accordance with the Page 1- 3 Pennichuck Water Works Watershed Management Plan 2.0 Watershed Characteristics Section Contents 2.1 Water Supply------2-1 The watershed land that surrounds and The supply is based on a series of 2.2 Base Flow/Surface Flow 2-2 contributes water to the chain ponds natural ponds increased by the 2.3 Climate------2-4 that make up Pennichuck’s water damming of Supply Pond at the 2.4 Land Uses ------2-4 system lies in five towns including Water Treatment Plant. Water is 2.5 Geology and Soils ------2-4 Nashua, Merrimack, Amherst, taken from Harris Pond 12 months of 2.6 Ponds and Channel Milford, and Hollis. This watershed the year and supplemented with Characteristics------2-5 supplies the chain ponds with water water from Supply Pond 6 months of through surface flow (runoff) and the year. Water from the Merrimack baseflow (groundwater). Figure 2-1 River is taken into Bowers Pond, depicts a watershed simplified in however, this study did not include the graphic form. Merrimack River.

Physical characteristics such as hydrology (how much water is contributed through rainfall and runoff), soil types and land uses in these town’s play an important role in the water quality of the ponds. As the towns within the watershed develop, the amount of surface flow is expected to increase carrying with it the pollutants contained on these surfaces. Simultaneously, clean groundwater “baseflow” into the system of ponds and streams is likely to decrease as more and more areas are paved. Thus, Figure 2-1. Simplified Watershed (adapted from A both current and future land uses in Watershed Approach to Urban Runoff: Handbook for each community have a significant Decisionmakers ) effect on both the amount of surface flow and the amount of pollution Table 2-1 summarizes pond reaching the ponds. characteristics for each of the chain ponds and for Pennichuck and Stump Ponds, including drainage area, water 2.1 Water Supply surface area and capacity (where The primary Pennichuck Water Works known). Smaller ponds such as water supply consists of about 351 Dunklee Pond and Round Pond that acres of water in a series of chain are included in the total surface water ponds that include Supply Pond, figures above are not included here. Harris Pond, Bowers Pond, and Holts There is no information on the storage Pond. Stump Pond, Pennichuck Pond, capacity of Stump, Pennichuck, Holts and many smaller ponds also and Supply Ponds. contribute water to Pennichuck’s supply. The total pond acreage is just For the purpose of this project, the under 2% of the total watershed area. total watershed tributary to Harris The sequence and sizes of these chain Pond and Supply Pond just upstream ponds is shown as Figure 2-2. of the water treatment plant was subdivided into ten natural subwatersheds.

Page 2-1 Pennichuck Water Works Watershed Management Plan 2.0 Watershed Characteristics

Table 2-1 A simplified graphic depiction of Pond Characteristics subwatersheds is shown in Figure 2-3. Pond Name Drainage Pond Pond The purpose of dividing a watershed Area Surface Storage into subwatersheds is to compare (acres) Area (acres) (MG*) characteristics such as drainage area, Stump Pond 1,516 21 Unknown Pennichuck Pond 4,295 57 Unknown topography and water surface area of Holts Pond 14,171 23 Unknown different portions of the watershed to Bowers Pond 15,955 92 180 at full allow later prioritization of pond recommendations. For example, Harris Pond 17,199 78 at spillover 340 at spillover various areas of the watershed can be Supply Pond 17,598 16 Unknown compared for hydrologic (total water inputs) and certain pollutant inputs to Table 2-2 determine which areas warrant the Subwatershed Characteristics Pennichuck Water Works Watershed greatest levels of protection from Subwatershed Name Land Water future threats and which ones need Area Surface correction of existing threats or (acres) Area insults. (acres) PBS - Pennichuck Brook to Supply Pond 1285 140 The subwatershed delineations include PBB - Pennichuck Brook to Bowers Pond 2390 94 four subdivisions of Pennichuck PBH - Pennichuck Brook to Holt’s Pond 1508 0 Brook, three subdivisions of Witches Brook, and separate subwatersheds for PBP– Pennichuck Brook to Pennichuck Pond 1978 89 Stump Pond Brook, Boire Field Brook WBE – Witches Brook East 1365 0 and Muddy Brook. Basic WBS – Witches Brook South 3193 0 characteristics for each subwatershed are shown on Table 2-2. Figure 2-4 WBN – Witches Brook North 1425 0 illustrates a basemap of the watershed SPB – Stump Pond Brook 1516 21 including the breakdown of the BFB – Boire Field Brook 1006 0 subwatersheds. MB1 - Muddy Brook 2317 7 Total Acreage 17,984 351 2.2 Base Flow / Surface Flow As watersheds become more developed, stormwater flows increase in intensity. This is because with development, impervious areas such as pavement, roofs, and streets slowly replace pervious agricultural lands and forests. Rainfall in impervious areas no longer penetrates and recharges groundwater, but instead runs overland into the nearest water course.

A 10-15% impervious cover can lead Figure 2-3. Aerial View of Typical Waters hed Boundaries to noticeable changes in channel (adapted from Watershed Protection Techniques, V1, N4, 1995.) morphology. It also may affect biological populations in the streams,

Page 2-2 Pennichuck Water Works Watershed Management Plan

2.0 Watershed Characteristics vegetative succession and water groundwater base flow inputs to chemistry. (Booth and Reinelt, 1993). streams. These groundwater base flow The volume of runoff is increased for inputs or discharges to streams are all storms, and the frequency of typically the component that allows occurrence of mid-bank full flow streams to become perennial or year events also increases. This is round streams as opposed to significant in terms of the stream’s intermittent stormwater based streams capacity to transport sediment, that dry up without rain. Because of increasing sediment transport. (Booth the cleansing effect of native soils, and Reinelt, 1993). base flow inputs are typically very high quality, and even As more severe and more frequent in contaminated areas, tend to be of floods occur, stream channels respond higher quality than stormwater inputs. by increasing their cross-sectional area to accommodate higher flows. Stream Ponds and lakes with large base flow banks may either widen or the stream inputs, which typically also have small bed may be down cut or both. This watersheds and thus small amounts of results in stream bank erosion and stormwater inflow, are typically much habitat degradation, as well as cleaner than ponds and lakes with increased sediment transport to water large watersheds and low base flow bodies. (Schueler, 1994). inputs.

Imperviousness can easily be measured at all scales of development, according to Schueler (1994) as the percentage of area that is not “green”.

Stream temperatures are also increased, and this is likely to affect the biological productivity of the stream, and may increase algae blooms and other eutrophication symptoms. Eutrophication is the process by which lakes and streams, because of pollutant inputs, are transformed from babbling brooks into odorous ponds of muck. This transformation goes hand-in-hand with the increase in storm flow and Figure 2-5. Simplified Groundwater Baseflow Diagram (adapted eventual decrease in groundwater base from A Watershed Approach to Urban Runoff: Handbook for flows. Decisionmakers ).

Groundwater base flow is the portion This highlights the importance of of the stream flow that is discharged groundwater inflow into the from groundwater when groundwater Pennichuck Pond system of ponds and levels are at a higher elevation than streams. However because of the the base of the stream. Figure 2-5 increasing imperviousness of the shows a simplified diagram of watershed due to development, this

Page 2-3 Pennichuck Water Works Watershed Management Plan 2.0 Watershed Characteristics

base flow appears to be decreasing. time while stormwater impacts have Studies in New York where sanitary heightened. sewers remove waste products from watersheds and transport them to 2.3 Climate ocean outfalls and where storm sewers transport water quickly to the nearest The climate of the area is typically waterway, have shown significant that of a North Temperate Zone with a reductions in base flow in streams. In mean annual temperature of about Long Island, water supply to streams 46.4°F. The climate is humid and is 95% from groundwater in rural characterized by fairly uniform areas, 84% from groundwater in semi- monthly precipitation, cold winters, urban areas (impervious cover, no and warm summers. The average sewers), and only 20% from annual precipitation for this region is groundwater in urbanized areas where about 43.07 inches. The growing there is impervious cover plus season averages about 160-180 days and generally lasts from May to Table 2-3. October. (Soil Survey of Hillsborough General Land Use Characteristics County, NH; 1981) of Pennichuck Watershed Communities Town 1996 Land Use Zoning % of Population Watershed 2.4 Land Uses Milford 12,000 Open Residential 8% space, Five towns make up this watershed; residential Amherst 10,000 Residential, Residential, 11% Milford, Amherst, Merrimack, Hollis industrial commercial and Nashua. Each town has its own industrial makeup of land uses determined by Merrimack 25,000 Residential, Residential, 19% industrial, industrial, zoning laws. The general commercial commercial characteristics of each town are , open space summarized in Table 2-3. A land use Hollis 6,420 Residential, Residential 40% map is included as Figure 2-6. agricultural and , park, open Agriculture, space Agriculture 2.5 Geology & Soils and Business, Recreational The soils and geology of the area play Nashua 81,000 Residential, Residential, 22% commercial commercial, an important role in the determination , industrial, industrial of phosphorus loadings in the water open space supply. Phosphorus is one of the pollutants of concern because it can stormwater and sanitary sewers. (Dry cause eutrophication of the ponds Weather Flow in Urban Streams, leading to algal blooms and taste and Center for Watershed Protection, odor problems. Eutrophication also Volume 2, Number 1, Fall of 1995). results in the filling in of ponds, which The Pennichuck capacity to supply can reduce the detention the ponds water from the Pennichuck Pond normally provide. A more detailed system has decreased as development discussion of the effects of phosphorus has increased. Although there are no and its relationship to area soils can be stream gauges available to chart the found in Section 4.0. decline, base flow has decreased over

Page 2-4 Pennichuck Water Works Watershed Management Plan

2.0 Watershed Characteristics

Steep slopes, erosive soils and poorly 2.6 Ponds and drained soils also result in greater pollutant loads to the reservoir. Channel Erosion allows sediment and attached pollutants to travel more quickly and Characteristics easily to surface waters by providing Chain pond systems characteristically channels for overland flow. Steep are cleanest in the most downstream slopes increase the velocity of flow pond. This is because upstream ponds and do not allow significant time for collect pollutants and trap them. infiltration. Poorly drained soils, such There they are subject to biological as clay, also keep runoff from degradation, unless excessive. In the infiltrating into the ground. Pennichuck watersheds, there are a series of ponds that trap many of the The soils of this area are underlain by urban pollutants that have entered over metamorphic and igneous rocks. The the years. However, it appears that metamorphic rocks are of the Littleton some of these ponds are becoming full Formation, which is composed of gray of sediment, resulting in washover of mica schist, and of the Merrimac polluted sediments and reduction in Group, which is composed of pinkish capacity. brown granulite and gray phyllite. Several areas of granite, quartz Table 2-4. monzonite, and granodiorite have been Summary of Effects of Watershed Characteristics on Water Quality forcibly injected up through the Physical Relationship to Water Quality Characteristics metamorphic rocks in this area. A Subwatersheds/ Subwatershed size, soils, slope, and hydrologic features detailed map of the soils in the Drainage Areas have significant effects on water quality both in natural and developed watersheds. Large drainage areas tend to have watershed is included in Appendix A. poorer water quality because of large stormwater inputs. The general soil types of the area Climate The amount of rainfall, seasonal variations in temperature, include: and rainfall patterns have a strong effect on both natural and urban watersheds. Land Use Watershed land use has a strong effect on water quality, · Hinkley-Windsor: deep, nearly with forests generally filtering out pollutants while urban level to steep, excessively drained, uses create many pollutants and increase stormwater levels. Stormwater/ Base Stormwater tends to be very poor quality from urban areas, gravelly and sandy soils on Flow while there is lesser stormwater impact in undeveloped terraces; areas. · Canton-Chatfield: deep and Geology and Soils The geology and soils may affect water quality because of the dissolved minerals that affect alkalinity, pH and other moderately deep, nearly level to natural features, including water bodies natural ability to moderately steep, well drained, process pollutants. loamy soils on hilly uplands; Ponds/Channel Ponds located in watersheds trap pollutants, making Characteristics downstream areas cleaner. Channel characteristics change · Bernardston Variant-Pennichuck- over time as urbanization increases stormwater flows, Canton: deep and moderately widening and deepening while transporting more sediments deep, nearly level to sloping, well drained loamy soils on rolling The loss of these ponds also affects uplands; and overall watershed storage for water. · Urban Land-Windsor-Canton: This loss of water storage ultimately urbanized areas and deep, nearly affects both the quantity and quality of level to sloping, excessively water, and the ponds must be drained, sandy and loamy soils on maintained in order to maintain good terraces and uplands. water quality in the water supply.

Page 2-5 Pennichuck Water Works Watershed Management Plan 2.0 Watershed Characteristics

Channel characteristics are dependent although little survey data exists. It is on the area of the watershed. In more likely that as the watershed urbanizes urban areas of the watershed, such as further, that the stream channels will in the lower portions of Nashua, the become wider and deeper and channels have scoured and widened, transport more sediment.

Page 2-6 Pennichuck Water Works Watershed Management Plan Section Contents 3.1 Introduction------3-1 3.0 Water Quality 3.2 Regulatory Background --3-1 3.3 Watershed Water Quality 3-3

watershed, although they are geared 3.1 Introduction more to protect aquatic habitat, fisheries and recreation than drinking Both raw and finished water quality water quality. These are also are important in drinking water described below. sources. Raw water is water before the treatment process begins. Finished Drinking Water Regulations water is the water that leaves the Both the Federal Safe Drinking Water water treatment plant and ends up at Act and New Hampshire Drinking the customer’s tap. It is important to Water Quality Standards identify maintain good water quality at both maximum contaminant levels (MCLs) these stages since good raw water that finished water must meet. Below quality can mean lower treatment is a brief discussion of each. costs and reduced taste and odor problems. Good finished water Safe Drinking Water Act quality is essential for public health. The Federal Safe Drinking Water Act An overview of Federal and State (SDWA), enacted in 1974, was regulations on water quality is amended in 1986 and 1996. SDWA included in this section. This is directs the compared with Pennichuck’s Environmental historical raw and finished water Protection Agency Good raw water quality quality data and with baseline (EPA) to develop sampling conducted by CEI for this primary drinking water can mean lower treatment project. Analysis of this data indicates regulations that costs and reduced taste problem areas and potential pollution incorporate maximum and odor problems. sources as discussed in Section 3.3 contaminant levels and later in Section 5.0. (MCLs), maximum contaminant level goals (MCLGs), and treatment techniques for dozens 3.2 Regulatory of contaminants to protect public Background health.

Drinking water regulations are based Some contaminants’ health effects are on the Federal Safe Drinking Water long-term, such as cancer or liver Act and amendments of 1986 and damage. Exposure to these 1996. The Act requires that each state contaminants over a long period of adopt standards that are no less time will increase the consumer’s stringent than the federal regulations. chance of contracting such diseases. Consequently, the MCLs for Surface water quality in the United contaminants that have long-term States is protected under the Clean (chronic) health effects are based on Water Act. These federal standards exposure to contaminants over a have been adopted by the State of lifetime. Regulations are then set with New Hampshire in the form of the assumption that drinking water Surface Water Standards designed to sources will be consumed regularly protect fisheries and recreational over an average lifespan of 70 years. water resources. These standards apply to all waters in the Pennichuck

Page 3-1 Pennichuck Water Works Watershed Management Plan 3.0 Water Quality

Other contaminants, such as source discharges of pollutants microbiologicals, have “acute” health (discussed further in Section 5). effects (those that occur immediately or shortly after consumption). Only State surface waters are broken into short-term exposure to these three classes (A, B, and C). The contaminants is needed before the classification of the water body is consumer becomes ill but there is dependent on the most sensitive use little or no lifetime cancer risk. These to be protected: Class A is the most contaminants are also regulated to protected and is generally for drinking assure public health safety. water supplies; Class B waters are generally for recreational use. Class C New Hampshire Department of waters consist of all surface waters Environmental Services (NHDES) not classified as Class A or B and are Drinking Water Quality the least protected. In addition, each Standards surface water body, regardless of classification, must meet the The New Hampshire Drinking Water following water quality criteria: Regulations (Env-Ws 310) mirror the SDWA regulations in a series of o The presence of pollutants in Maximum Contaminant Levels receiving waters is not the basis (MCLs) and Maximum Contaminant for further introduction of Level Goals (MCLGs). pollutants. The failure of waters They address the quality to meet certain criteria due to The number of regulated of water after treatment natural causes does not drinking water (finished water) before it necessitate the modification of the reaches the consumer. contaminants has assigned water use classification. Table 3-1 shows the o All waters shall be free from increased from less than 20 MCLs and MCLGs of pollutants in concentrations or to more than 100 in the last some common combinations that settle to form contaminants compared 10 years. harmful deposits; float; produce to Pennichuck’s finished odor, color, taste, or turbidity that water quality. is not naturally occurring; result in the dominance of nuisance Surface Water species; or prevent recreational Quality Regulations activities. NHDES also has surface water o The level of radioactive materials quality regulations (Env-Ws 432) that shall not be in concentrations or refle ct the federal Clean Water Act combinations that would be requirements. The purpose of these harmful to human, animal, or rules is to establish standards based aquatic life; would result in on the designated use of the surface radionuclides in aquatic life water. The rules provide for the exceeding recommended limits protection of aquatic organisms and for consumption by humans; or wildlife and provide for recreational would exceed EPA’s Drinking activities within the state’s waters. Water Regulations. The Surface Water Quality o Tainting substances shall not be Regulations also apply to all point present in combinations that (piped) and non-point (stormwater) individually or in combination

Page 3-2 Pennichuck Water Works Watershed Management Plan 3.0 Water Quality

Table 3-1. NHDES Drinking Water Standards Compared to Pennichuck Finished Water

Pennichuck Finished 1 MCLG MCL Water Notes For systems collecting at least 40 samples per month, no more than 5% can be total coliform positive. For systems collecting less than 40 samples per month, no more than one sample Total Coliform 0 mg/l Absence Absence can be coliform positive. Fecal Coliform 0 mg\l Absence Absence Any positive sample must be reported. Giardia Lamblia 0 mg/l 0 mg/l ~ Microbiological contaminants only monitored Viruses 0 mg/l 0 mg/l ~ after disease outbreaks. Legionella 0 mg/l 0 mg/l ~ Cryptosporidium 0 mg/l 0 mg/l ~ Heterotrophic Plate Counts 0 mg/l 0 mg/l <1 Turbidity is measured at representative entry points. Five NTU may be permitted if higher turbidity does not result in interference with 0.3 NTU / 0.05 disinfection or microbiological Turbidity 1 NTU 1 NTU before lime determinations. Adjusted Gross Alpha 0 piC/l ~ Alpha radionuclides, not usually a concern in Gross Alpha 0 piC/l 15 piC/l ~ surface water supplies. Radium 226 + 228 0 piC/l 5 piC/l ~ Radon 0 piC/l ~ Uranium 0 piC/l ~ This is an average annual concentration from Beta Particles and Photon man made radionuclides, not usually a Radioactivity 4 mrem/year ~ problem in surface water supplies. Gross Beta 0 piC/l ~ Beta radionuclides are not usually a problem Radium 228 0 piC/l ~ in surface water supplies. Tritium 0 piC/l 20,000 piC/l ~ Strontium 90 0 piC/l 8 piC/l ~ Arsenic 0.05 mg/l <0.005 Inorganic metals contaminants 7 million 7 million Asbestos fibers/l fibers/l ~ Barium 2.0 mg/l 2.0 mg/l <0.002 Cadmium 0.005 mg/l 0.005 mg/l <0.0025 Chromium 0.1 mg/l 0.1 mg/l <0.05 The MCL indicated here is actually the action level. When copper concentrations exceed 1.3 ppb in more than 90% of their samples, action must be taken for treatment. Copper usually comes from homeowners plumbing. Copper 1.3 mg/l 1.3 ppb <0.10 Fluoride 4.0 mg/l 4.0 mg/l <1.0 Limitation for treatment level. When lead concentrations exceed 15 ppb in more than 90% of their samples, action must be taken for treatment. Lead problems usually come from home plumbing. Lead 0 mg/l 0.15 mg/l <0.005 Inorganic contaminant Mercury 0.002 mg/l 0.002 mg/l <0.001

Pennichuck Water Works Watershed Management Plan 3.0 Water Quality

Table 3-1. NHDES Drinking Water Standards Compared to Pennichuck Finished Water

Pennichuck Finished 1 MCLG MCL Water Notes The total for nitrate and nitrite cannot exceed Nitrate 10 mg/l 10 mg/l 0.66 10 mg/l, which is not usually a problem in Nitrite 1.0 mg/l 1.0 mg/l <0.005 surface waters. Selenium 0.05 mg/l 0.05 mg/l <0.025 Inorganic contaminants. Antimony 0.006 mg/l 0.006 mg/l <0.003 Beryllium 0 0.004 mg/l <0.002 Cyanide 0.2 mg/l 0.2 mg/l <0.001 Nickel 0.1 mg/l 0.1 mg/l <0.05 Thallium 0.0005 mg/l 0.002 mg/l <0.001 Benzene 0 mg/l 0.005 mg/l BDL Organic contaminants, mostly volatile and not Carbon tetrachloride 0 mg/l 0.005 mg/l BDL usually a problem in surface waters. 1,2 dichloroethane 0 mg/l 0.005 mg/l BDL Trichloroethylene 0 mg/l 0.005 mg/l BDL Para dichlorobenzene 0.075 mg/l 0.075 mg/l BDL 1,1 dichloroethylene 0.007 mg/l 0.007 mg/l BDL 1,1,1 trichloroethane 0.2 mg/l 0.2 mg/l BDL Vinyl chloride 0 mg/l 0.002 mg/l BDL Cis 1,2 dichloroethylene 0.07 mg/l 0.07 mg/l BDL 1,2 dichloropropane 0 mg/l 0.005 mg/l BDL Ethylbenzene 0.7 mg/l 0.7 mg/l BDL Monochlorobenzene 0.1 mg/l 0.1 mg/l BDL 0 Dichlorobenzene 0.6 mg/l 0.6 mg/l BDL Styrene 0.1 mg/l 0.1 mg/l BDL Tetrachloroethylene 0 mg/l 0.005 mg/l BDL Toluene 1 mg/l 1 mg/l BDL Trans 1,2 dichloroethylene 0.1 mg/l 0.1 mg/l BDL Xylene, Total 10 mg/l 10 mg/l BDL Dichloromethane 0 mg/l 0.005 mg/l BDL 1,2,4 Trichlorobenzene 0.009 mg/l 0.07 mg/l BDL 1,1,2 Trichloroethane 0.003 mg/l 0.005 mg/l BDL Synthetic organic contaminants (mostly Alachlor 0 mg/l 0.002 mg/l BDL pesticides). Usually a greater problem in Aldicarb 0.001 mg/l 0.003 mg/l BDL heavy agricultural areas of the midwest. Aldicarb sulfoxide 0.001 mg/l 0.004 mg/l BDL Aldicarb sulfone 0.001 mg/l 0.002 mg/l BDL Atrazine 0.003 mg/l 0.003 mg/l BDL Carbofuran 0.04 mg/l 0.04 mg/l BDL Chlordane 0 mg/l 0.002 mg/l BDL Dibromochloropropane 0 mg/l 0.0002 mg/l BDL Ethylene Dibromide 0 mg/l 0.00005 mg/l BDL Heptachlor 0 mg/l 0.0004 mg/l BDL Heptachlor Epoxide 0 mg/l 0.0002 mg/l BDL Lindane 0.0002 mg/l 0.0002 mg/l BDL Methoxychlor 0.004 mg/l 0.04 mg/l BDL PCBs 0 mg/l 0.0005 mg/l BDL Pentacholophenol 0 mg/l 0.001 mg/l BDL Toxaphene 0 mg/l 0.003 mg/l BDL

Pennichuck Water Works Watershed Management Plan 3.0 Water Quality

Table 3-1. NHDES Drinking Water Standards Compared to Pennichuck Finished Water

Pennichuck Finished 1 MCLG MCL Water Notes 2,4,5 TP 0.05 mg/l 0.05 mg/l BDL Synthetic organic contaminants (mostly 2,4 D 0.07 mg/l 0.07 mg/l BDL pesticides). Usually a greater problem in Dalapon 0.2 mg/l 0.2 mg/l BDL heavy agricultural areas of the midwest. Di(ethylhexyl)adipate 0 mg/l 0.4 mg/l BDL Di (ethylhexyl) phthalate 0 mg/l 0.006 mg/l BDL Butylbenzylphathalate 0.04 mg/l 0.007 mg/l BDL Dinoseb 0.007 mg/l 0.007 mg/l BDL Diquat 0.02 mg/l 0.02 mg/l BDL Synthetic organic contaminants (mostly Endothall 0.1 mg/l 0.1 mg/l BDL pesticides). Usually a greater problem in Endin 0.002 mg/l 0.002 mg/l BDL heavy agricultural areas of the midwest. Glyphosate 0.7 mg/l 0.7 mg/l BDL Hexachlorobenzene 0.05 mg/l 0.001 mg/l BDL Hexachlorocyclopentadiene 0.05 mg/l 0.05 mg/l BDL Oxamyl 0.2 mg/l 0.2 mg/l BDL PAH 0 mg/l 0.00002 mg/l BDL Picloram 0.5 mg/l 0.5 mg/l BDL Simazine 0.001 mg/l 0.004 mg/l BDL 2,3,7,8 TCDD Dioxin 0 mg/l .00000003 mg/l ~ Bromodichloromethane 3 Trihalomethanes (THMs), monitoring is Dibromochloromethane <1 required in systems that serve 10,000 or more. TribromomethaneTotal of 100 <0.1 Trichloromethaneppb 20 Chloroform 0 mg/l 0.02 Maximum Disinfection Byproducts. Bromodichloromethane 0 mg/l 0.003 Bromoform 0 mg/l <0.0001 Bromate 0 mg/l ~ Dichloroacetic Acid 0 mg/l 0.011 Trichloroacetic Acid 0.1 mg/l 0.009 Chloral Hydrate 0.005 mg/l ~ Chlorite 0.3 mg/l ~ Dibrochloromomethane 0.06 mg/l ~ Chlorine 4 mg/l 0.85 Chlorine Disinfectant Residuals. Chloramines 4 mg/l ~ Chlorine Dioxide 0.8 mg/l ~ 0.05% dose at Limitations for Treatment Chemicals. Acrylamide 0 mg/l 1 mg/l ~ 0.01% dose at Epichlorohydrin 0 mg/l 20 mg/l ~ ~ Not sampled mg/l - milligrams per liter BDL - Below Detection Limit ppb - parts per billion 1.) Pennichuck Samples represent an average of the finished water at Harris Pond taken since 1991.

Pennichuck Water Works Watershed Management Plan 3.0 Water Quality

produce undesirable flavors in included a field analysis of pH, aquatic organisms. conductivity, turbidity, dissolved o Toxic pollutants, unless naturally oxygen (DO), temperature and flow occurring, shall be in rate. Laboratory analysis was concentrations that will not injure conducted for fecal coliform, plants, animals, humans or ammonia, Total Kjedhal Nitrogen aquatic life; persist in the (TKN), total phosphorus, and nitrate. environment; or accumulate to harmful levels in aquatic Based on the hydrologic budget and organisms. breakdown of subwatersheds, 13 key locations in the watershed were The chain ponds that consist of identified for sampling. Sampling was Pennichuck Water Works’ supply are done at four dams (SW1, SW2, SW4, classified as Class A water bodies and and SW6) and nine tributaries (SW3, must meet the criteria provided in SW5 and SW7-SW13). Locations of Table 3-2. Table 3-2 is a comparison these sampling points can be seen in of Pennichuck’s current water quality Figure 3-1. The relationship of these and these criteria. locations to historically sampled locations is described 3.3 Watershed Water in the appendix. Some of the most useful Quality Fecal Coliform parameters for gauging The most useful parameters for Fecal coliform is watershed health are not gauging watershed health are not all typically used as regulated. Table 3-3 describes some indicators of regulated. of the most useful watershed bacteriologic pollution management parameters. Data on in water. These these parameters (some regulated, bacteria may indicate animal and/or some not) is discussed below. human fecal wastes that can be identified and potentially eliminated Pennichuck Water Works has or minimized to improve water conducted historical sampling of quality. However, there are many several parameters in the watershed. limitations in the accuracy of these Historical sampling data and a map of “indicators” because some bacteria in their locations is included in the coliform group are not of fecal Appendix B. origin. Thus, the test can give misleading results, particularly when Baseline sampling was conducted counts are fairly low (<100 per ml) in during the months of July, August, untreated surface water. and December. The results of this sampling are included in Appendix C. Pets in densely populated areas, livestock and sewage leaks near Limited additional sampling was surface waters are typical sources of conducted for this study to fecal coliform. Fecal coliform is also supplement existing data for nutrients used to indicate whether other and pathogens, two of the most pathogens may be present; pathogens detrimental contaminants to a surface that may include viruses, bacteria, and water supply. Sampling parameters protozoans like Giardia and

Page 3-3 Pennichuck Water Works Watershed Management Plan 3.0 Water Quality

Cryptosporidium. Some of these used as an adjunct to fecal coliform pathogens are difficult to treat, counts. Meanwhile, fecal coliform particularly the protozoans, and may analysis supplemented with analysis lead to severe cases of diarrhea or for Escherischia coli (E. coli) are the dehydration (which can be fatal to the most reliable indicators available for immuno-compromised). These identifying fecal wastes. pathogens are not typically tested for because reliable methods are not Fecal coliform data from January generally available. 1991 to July 1996 indicates specific Figure 3-2. Results of 1996 Fecal areas of the watershed with frequently Coliform Analysis high fecal counts (>100 per ml), with the highest counts generally occurring Fecal Coliform during the summer months. 350 300 Review of the six years of data 250 suggests an increase in fecal counts in 200 150 most locations over time. # / 100 ml 100 50 High fecal coliform counts were 0 identified at Boire Field Brook July 1996 August 1996 December 1996 (SW3), Stump Pond (SW10), and SW-1 Supply Pond Dam SW-2 Harris Pond Dam SW-3 Boire Field Brook SW-4 Bowers Pond Dam Witches Brook (SW11 and SW12), SW-5 Bowers Pond Mid SW-6 Holts Pond Dam SW-7 Pennichuck Brook SW-8 Pennichuck Pond Mouth SW-9 Muddy Brook SW-10 Stump Brook with counts remaining above 100 SW-11 Witches Brook SW-12 Witches Brook SW-13 Witches Brook from Boire Field Brook during the winter months when lower counts are

expected. Possible sources for these Total Phosphorus high counts are sewer breaks, illegal ~0.55~ waste discharges or pets in densely 0.2 ~0.21~ 0.18 populated areas. Figure 3-2 shows the 0.16 results of fecal coliform sampling. 0.14 0.12 0.1 mg/l Phosphorus 0.08 0.06 Phosphorus is considered a limiting 0.04 0.02 nutrient for plant life to grow. 0 However, if excessive phosphorus can Average of One sample Average of One sample One sample available samples taken in April available samples taken in June taken in July cause ponds to fill in and become taken during 3 taken during 4 sampling rounds sampling rounds eutrophic with algae blooms that lead in November in May to taste and odor problems in water Supply Pond Harris Pond Bowers Pond supplies. Generally, phosphorus Holt Pond Behind NHVT Pennichuck Brook Stump Pond levels under 0.02 – 0.03 mg/l will not Figure 3-3. Historical Phosphorus lead to eutrophication or algae Levels blooms. Limited phosphorus data taken since November 1995 shows values as high as 0.21 mg/l. As can be Some researchers are currently close seen from Figure 3-3, the highest to completing work in better phosphorus levels occur in Bowers “indicator” organisms that can be Pond, Pennichuck Brook and the Merrimack River, with significant

Page 3-4 Pennichuck Water Works Watershed Management Plan 3.0 Water Quality

Table 3-2. NHDES Class A Surface Water Quality Standards Compared to Pennichuck Raw Water

Parameter Standard Values Found in PWW System Dissolved Oxygen DO = 75% saturation for 16 Typical DO values range from 8-10 mg/l in cold, well- hours/day, not less than 6 mg/l aerated streams and from 3-5 mg/l in warm streams. DO unless naturally occurring. values during CEI's sampling rounds ranged between 2.8 mg/l and 11.9 mg/l. Low values may suggest oxygen depletion and potential for fishkills. High values may suggest excessive algae. Benthic Deposits No benthic deposits unless NS* naturally occurring. Coliform No coliform in quantities that Typically, for drinking water, fecal values should be will impair water uses. absent. High fecal counts occurred at Boire Field Brook, Stump Pond, and Witches Spring Brook. Oil and Grease No oil or grease, unless NS* naturally occurring. Color No color unless naturally Color values in 1996 ranged from < 1 color unit to 73 occurring color units. Color does not pose a health threat, however it may be an aesthetic problem. Most colors result from decaying plants and may not represent a pollution issue.

Turbidity No turbidity unless naturally Turbidity indicates the amount of total suspended solids in occurring. water. High turbidity may interfere with treatment. Harris Pond, Bowers Pond, and Boire Field Brook showed high turbidity values at times. Slicks, Odors, and Surface No slicks, odors, or surface None noted. Floating Solids floating solids. Temperature No artificial rise in temperature. None noted.

Phosphorus No phosphorus unless naturally Phosphorus levels range from 0.02 to 0.21 mg/l in the occurring. chain ponds. Desired levels are usually around 0.02 to 0.03 mg/l in a stream system like this. High levels may lead to eutrophication of the ponds. Modeling indicated high values may occur at PBB and SB. Gross Beta Radioactivity < 1000 picocuries per liter NS* Stronium-90 < 10 picocuries per liter NS* Radium-226 < 3 picocuries per liter NS* pH As naturally occurs. Over-productive reservoirs may see fluctuations in pH as vegetation and algae photosynthesize (high pH) and respire (low pH). pH ranged from 4.0 to 10.5 at various locations in the watershed. High or low pH may also indicate industrial discharges. Toxic Substances Ambient water concentration NS* should be zero, however, as this is not attainable, a risk factor of 10-6 is used. Dioxin (2,3,7,8 - TCDD) < 0.001 mg/l NS* Mixing Zones Not allowed in Class A waters. NS*

Antidegradation No discharge of sewage or No point discharges noted. wastes into Class A waters. Degradation of water quality is prohibited. NS* These parameters are not typically sampled (or are not sampling parameters) unless a specific indisutrial discharge were suspected.

Pennichuck Water Works Watershed Management Plan 3.0 Water Quality Table 3-3. Useful Watershed Water Quality Parameters and Their Meaning Parameter Importance to Surface Water Supply pH A measure of the concentration of ions (H+) in water. Over-productive reservoirs may see fluctuations in pH as vegetation and algae photosynthesize (high pH) and respire (low pH). Excessively high (>9) or low (<4) pH may also suggest industrial wastes. Temperature Typically, in winter months, temperatures range from 0-3º C, in summer months, temperatures range from 23-27º C. Variations in temperature may be an indication of wastewater discharges. Stream temperatures that are low in the summer can also suggest a groundwater baseflow influence, usually a positive factor. Urban development tends to increase overall stream temperatures by removing shade trees and by long-term loss of baseflow. Turbidity Turbidity is a measure of the total suspended solids in water and is used to assess the clarity of water. Erosion and algal blooms from construction projects are common causes of high turbidity in ponds and streams. Construction erosion is particularly problematic because many pollutants adsorb to soil particles and are carried along. It also causes sediment build up in ponds. Conductivity Conductivity is a measure of the ability of water to conduct electricity, also a measure of the total dissolved solids in water. Higher than background levels may suggest sewage or other pollutant inputs. Color Color results from dissolved materials in water. Most colors in natural waters result from tannins extracted from decaying plants. Alkalinity A measure of the water’s ability to neutralize acids or buffering capacity. Indicates the water’s ability to resist pH change. pH changes may strongly affect other parameters. For example, low pH may cause release of heavy metals from sediments. Dissolved Oxygen (DO) The presence of DO is important to maintain aquatic life in waters. Typical DO values range from 8-10 mg/l in cold, well-aerated streams, in warm streams, 3-5 mg/l. Very high summer DO may suggest algal blooms. The algal bloom may add to oxygen levels in the daytime, but oxygen demand from decomposing sediment materials causes associated nighttime crashes. This condition can lead to fish kills and other undesirable water quality effects such as the release of manganese and phosphorus from sediments. Fecal Coliform The presence of fecal coliform in high numbers may be an indication of feces from animal or human waste. Escherischia coli This analysis may be used to confirm whether a suspected fecal coliform problem is (E. coli) really from fecal wastes. It is an enteric bacteria from warm blooded animals or humans. Coliphages This test is now under development and will help differentiate between human and animal wastes. It is not yet readily available commercially. Phosphorus Phosphorus is an essential element for the growth of algae and other aquatic plant life. In high concentrations that often result from development, it leads to eutrophication. Eutrophication is the process where excessive algae and aquatic plant growth may choke waterways and may cause fish kills and unpleasant odors. Total Kjeldahl Nitrogen TKN comprises nitrogen in all its forms, organic, ammonia, and nitrate. High TKN (TKN) values may indicate a nitrogen source. However, ammonia nitrogen and/or nitrate nitrogen may also be sampled to help identify a specific source. Ammonia Ammonia occurs in anaerobic conditions and is readily used by aquatic vegetation. Ammonia is a naturally-occurring form of nitrogen, but there are also several manmade sources. Common sources of ammonia are urea and anhydrous ammonia (fertilizer). Ammonia is found in the highest concentrations below wastewater discharges. High levels of this may indicate a nearby pollution source (waste discharge or fertilizer near a stream). Nitrate Nitrate is a soluble form of nitrogen. Ammonia is converted to nitrate by bacteria and plants and occurs in almost all natural waters. Levels of nitrate seldom exceed 3 or 4 mg/l by natural occurrence in New England. High nitrate levels may indicate contamination from fertilizers, municipal wastewaters, feedlots, or septic systems.

Pennichuck Water Works Watershed Management Plan

3.0 Water Quality levels in Bowers Pond after heavy recommended to more accurately rainfall (5/1/96 and 5/2/96), indicating assess the health of the ponds and the impacts stormwater has in this surrounding watersheds. This is area. discussed further in the recommendations section. Since phosphorus is the limiting nutrient for freshwater aquatic plants Nitrate (they typically run out of this before Nitrate occurs in most natural waters, other nutrients), most watershed however, too much nitrate in surface programs are aimed at reducing its waters has the same result as levels as the most effective method of phosphorus algae blooms and excess preserving the watershed. Further, in plant growth that may choke order to limit this nutrient, its sources waterways. Boire Field Brook, Stump must be known. Since this would take Pond and Witches Brook show the years of intensive sampling to identify highest nitrate levels. Although the through direct analysis, theoretical quantities are not large enough to models are often used to shorten the present a compliance problem, they process of identifying the best targets may lead to the eutrophication of the for prevention and remediation ponds. These subwatersheds are the efforts. Since most of these models most developed areas in the are based on land use, they can also watershed. Some common sources of provide a more accurate long-term nitrate are contamination from projection of phosphorus loads. They fertilizers, municipal or livestock can also be used, as they were here, to wastewater, and leaking septic predict future water quality based on systems. current zoning and the “buildout” of communities under this zoning. In summary, while The theoretical model used for the Pennichuck easily meets Pennichuck system helped to determine phosphorus loads to the all drinking water chain ponds in Pennichuck’s system. standards, raw water This model highlighted areas of bacteria and nutrients are greater phosphorus load and helped pinpoint sources of pollution. Section troublesome and may lead 4 discusses the phosphorus loading to increased treatment model in detail. Common sources of costs in the future. Even phosphorus are urban development, gravel operations, agriculture and more critical is the logging. increasing inability to

The phosphorus model is best used to “store” water in the compare various areas of the watershed. Urbanization watershed to one another to identify will continue to reduce the potential problem areas. It does not take the place of actual data, rather it available water supply. supplements data collection efforts. A long-term monitoring plan is also

Page 3-5 Pennichuck Water Works Watershed Management Plan Section Contents 4.0 Hydrology and Nutrient 4.1 Hydrology ------4-2 4.2 Nutrient Analysis------4-3 Modeling

A hydrologic budget of the loadings each contributes so that watershed, using precipitation and specific subwatersheds may be gaging station flow correlations, was identified for preventive and remedial developed to identify the total runoff efforts. For example, a subwatershed (surface and base flow) entering the that contributes 18% of the total chain pond system from the phosphorus loadings is more critical individual subwatersheds. This is to the system than a subwatershed critical because it allows the that contributes only five percent of subwatersheds to be prioritized based the total phosphorus loadings, and on the amount of water contributed to consequently should receive more the chain pond system from each, effort for preventive and remedial with larger contributors being more efforts. critical to the system. For example, a subwatershed contributing 28% of the In summary, the hydrologic and total flow into the ponds is more nutrient budgets allow for later critical than a subwatershed prioritization of efforts. Table 4-1 contributing only two percent of the outlines the purpose of the hydrologic total flow because its impacts on the and nutrient budgets. final water quality of the ponds are greater. Table 4-1 Purpose of Hydrologic/Nutrient Budgets The precipitation data used in the The hydrologic contributions hydrologic analysis was then used for Allows from each subwatershed can be further modeling calculations of Comparison of Subwatersheds compared and projects can be pollutant loadings of the critical focused in areas that contribute parameter phosphorus. Phosphorus is the greatest amount of water; critical because it is the limiting nutrient in a fresh water system, and it The nutrient budget shows is important to reduce its loading into Allows Focus on areas contributing the highest the ponds to minimize algal blooms Problem Areas amounts of phosphorus, a and associated taste and odor for critical nutrient in the long-term problems. It is also critical to reduce Remediation health of fresh surface water phosphorus because excess amounts bodies; lead to eutrophication, the rapid filling-in of water bodies with dead plant materials and the associated loss Allows Focus on Remediation projects can be of capacity (and other problems). Good Quality focused in the areas of high Areas for phosphorus contribution, while The phosphorus modeling gives a Prevention/ prevention projects can be picture of the anticipated overall Protection targeted to areas of high volume and low phosphorus quality of water in each of the chain contribution. ponds and the major contributions to that water quality from various portions of the watershed. It allows for each of the subwatersheds to be prioritized based on the phosphorus

Page 4-1 Pennichuck Water Works Watershed Management Plan 4.0 Hydrology and Nutrient Modeling

4.1 Hydrology Hydrology refers to the occurrence, circulation and distribution of surface and ground waters. A hydrologic budget is performed to identify the amount of water entering a surface water body. Water may enter through runoff as surface flow in streams, sheet flow over land, and groundwater flow through the subsurface. Additionally, it may enter through direct precipitation. It “exits” the watershed via evaporation and transpiration and outflow. A graphical depiction of water contribution is shown in Figure 4-1. Calculating the components on each side of the equation can be used to develop a “budget” as is described below. Figure 4-1. Typical Hydrologic Cycle The hydrologic analysis conducted for this study consisted of the PBS MB 5% delineation of several subwatersheds 15% and an analysis of gaging station and PBB 16% precipitation data to determine the BFB total runoff (surface and baseflow) 2% from each subwatershed into the SPB chain ponds. The estimated percent 6% PBH hydrologic contribution into Supply WBN 6% Pond by subwatershed is shown on 6% Figure 4-2. The subwatershed delineations are shown on Figure 4-3. PBP 11% The estimated runoff from the total watershed for a series of varied WBE conditions was determined by WBS 5% 28% analyzing available precipitation and runoff records for the local area. Figure 4-2. Percent Hydrologic Monthly precipitation records for Contribution Nashua, covering a 74-year period, from 1922-1995, were used in the analysis, with a focus on the 30-year period of 1966-1995. Runoff estimates for the area were based on analysis of several gaging station

Page 4-2 Pennichuck Water Works Watershed Management Plan

4.0 Hydrology and Nutrient Modeling records as obtained by the U.S. contributions from each subwatershed Geological Survey. as depicted in Figure 4-2. A more detailed description of the hydrologic The runoff values used for the analysis is provided in Appendix D. Pennichuck watershed were derived from a study of records compiled by 4.2 Nutrient Analysis the U.S. Geological Survey from certain continuous record streamflow A nutrient analysis of the watershed, monitoring stations including a using phosphorus, was conducted to gaging station on the Souhegan River show: (1) the total loadings into the at Merrimack, N.H. and a gaging chain pond system from each of the station at Beaver Brook at North subwatersheds and (2) the in-pond Pelham on the Pelham-Windham concentrations from each of the chain town line. These data records were ponds based on these total loadings. used to derive relationships between The analysis was conducted using a flow data recorded and monthly and phosphorus model that projects annual precipitation. estimated phosphorus loadings from various portions of the watershed A study of annual precipitation at based on land use and soils data. Nashua and flow data at the Souhegan Modeling is especially useful in River at Merrimack for the 54-year watersheds where there is limited period (1923-1976) shows a very sampled phosphorus data. However, distinct relationship between modeling provides only a rough precipitation and flow contribution as with 49 of the 54 years falling within the 90% probability range as shown Table 4-2. Frequency Analysis of 54-year Period in more detail in Appendix D. This of Precipitation relationship can be used to estimate the annual runoff from the watershed % of Time Annual Amount of Precipitation given a value for precipitation. For Precipitation is Less Than (inches) example, the average annual Stated precipitation of 43.66 inches for the 1% 27.5 30-year period (1966-1995) would be 2% 28.8 expected to yield an average runoff 5% 30.9 value of 25.65 inches with a 90% 10% 32.9 probability that the annual rainfall 20% 35.4 producing this contribution would fall 30% 37.2 within the range of 37.8 to 49.5 70% 44.5 inches. A frequency analysis for this 80% 47.2 54-year period of rainfall shows the 90% 50.5 results in Table 4-2. 95% 54.0 98% 57.8 The runoff values determined through 99% 60.2 this analysis were applied to the Pennichuck water supply watershed to determine the percent hydrologic

Page 4-3 Pennichuck Water Works Watershed Management Plan 4.0 Hydrology and Nutrient Modeling

MB PBS 5% BFB 10% estimate of pollutant loadings in the 10% reservoir and is better used to compare various portions of the watershed to one another. PBB 18% Since the Pennichuck watershed is SPB divided into 10 subwatersheds, the 16% phosphorus loadings from each of these subwatersheds was estimated to identify which areas contribute the most phosphorus. Thus, these areas PBH WBN 10% could become the focus for later 8% prioritization efforts. Figure 4-4 summarizes the percent phosphorus WBS PBP contribution of each of the 8% WBE 8% 7% subwatersheds to the chain ponds.

Table 4-3 shows the same Figure 4-4. Percent Phosphorus subwatersheds compared for both Contribution hydrologic and nutrient contributions.

The Eutromod Watershed and Lake Table 4-3. Comparison of Hydrologic and Modeling Software (Reckhow, 1990) Phosphorus Contributions by Subwatershed was used for determining phosphorus Subwatershed % Hydrologic Percent contributions in the Pennichuck Contribution Phosphorus watershed. The model uses Contribution information pertaining to land uses, soils, stormwater pollutant PBS Pennichuck Brook 5% 10% concentrations, and pond to Supply Pond characteristics to estimate phosphorus PBB Pennichuck Brook 16% 18% loadings and in-pond phosphorus to Bowers Pond concentrations. This model was PBH Pennichuck Brook 6% 10% selected because it was developed to to Holt’s Pond determine phosphorus loadings from PBP Pennichuck Brook 11% 8% both rural and urban settings, while to Pennichuck Pond many models focus only on urban WBE Witches Brook 5% 7% watersheds. East WBS Witches Brook 28% 8% The model considers phosphorus South loadings from agricultural areas, since WBN Witches Brook 6% 8% they may contribute more than North another type of land use of similar SBP Stump Brook 6% 16% size. The model also accounts for Pond phosphorus loadings from forested BFB Boire Field Brook 2% 10% areas, considering the phosphorus MB Muddy Brook 15% 5% content of the regional soils. This is

Page 4-4 Pennichuck Water Works Watershed Management Plan 4.0 Hydrology and Nutrient Modeling important because some of the than one acre in size. Although this Pennichuck watershed is very rural land use does not provide the same with small tracts of agricultural land level of protection as forested lands, it and large tracts of undeveloped is one of the more desirable forested land, while other parts are developed land uses since the amount rapidly urbanizing. Thus this model of impervious area remains relatively was appropriate for this watershed. low in comparison to dense Additionally, Pennichuck zoning residential, industrial and commercial reveals that some areas of the town of areas. Hollis may develop as agricultural land in the future. Several of the In addition to land use data, soils data urban models do not recognize the was also defined for use in the model. high loadings that may be seen from This was obtained through the UNH these agricultural areas. In addition to GRANITNET calculating loadings from various database and is Phosphorus is critical because it land uses, the model also uses these provided in is the limiting nutrient in a fresh estimated loadings to determine Appendix A. These water system, and it is important theoretical in-pond phosphorus land areas and soils to reduce its loading into the concentrations. data are used to determine literature ponds to minimize algal blooms Phosphorus Loadings based surface runoff and associated taste and odor The Eutromod model requires an coefficients for urban problems. and rural areas of the extensive inventory of the watershed to identify the watershed specific watershed (obtained parameters to successfully run the from Reckhow, model. The parameters needed to run 1990). Runoff the model are summarized in Table 4- coefficients for the rural areas within 4. Specific factors applied for each of the watershed were estimated based the parameters in each subwatershed on literature coefficients for specific can be found in Appendix E. soil types. For urban areas, these The first step for using the model is to coefficients are based on the percent define the various land uses within impervious area, identified in the the watershed by land area. This data literature for individual urban land was obtained from the Nashua uses including commercial, industrial Regional Planning Commission and various densities of residential. (NRPC) for 1994 and is shown as These impervious areas have been Figure 4-5. Land areas for each land correlated with runoff coefficients. use in each subwatershed are The model uses these runoff summarized in Table 4-5. Note that coefficients to determine the total about half of the watershed is surface runoff within a given area. undeveloped forested land (vacant The land use data is also used to land), which, in itself, provides a identify literature-based phosphorus significant level of protection as long concentrations for stormwater runoff as it is not developed. Additionally, from various land uses. about 19% of the watershed is developed as residential lots greater

Page 4-5 Pennichuck Water Works Watershed Management Plan 4.0 Hydrology and Nutrient Modeling

The model estimates phosphorus since not all of the eroded soils will loadings from a given area by reach a stream or water body. Due to multiplying the quantity of surface the dense cover on forested lands, runoff by the phosphorus little soil erosion is expected to occur concentrations for specific land uses. in the forested areas. The model also uses the universal soil loss equation (USLE) to determine For urban areas, it is generally the amount of eroding soil in the rural assumed that all of the stormwater areas of the watershed including and its pollutants will reach the agricultural and forested lands to stream since pipes are available to account for the phosphorus content carry the stormwater into the that may be transported in the surface tributary. However, there is no storm runoff from these areas. The equation drain system in portions of the uses various factors based on the type watershed so a trapping factor was and slope of the applied for the developed areas within Approximately 7,000 pounds soils. The local Soil these subwatersheds to account for Conservation Service runoff onto pervious surfaces, where per year of phosphorus are was contacted to some of the surface flow infiltrates contributed to the chain pond assist in the use of into the ground. system from the watershed. this equation. The purpose of the USLE Using the information provided in is to determine the Appendix E and described in Table 4- soil attached 4, the model was run and phosphorus phosphorus loadings loadings by subwatershed and by type due to erosion. These of land use were estimated. These are are estimated with the use of literature summarized in Table 4-6. Based on based coefficients for soils in the area. the results of the model, a total of approximately 7,000 pounds of Finally, the model allows for a phosphorus per year are contributed trapping factor, which estimates the to the chain pond system from the amount of soil or pollutants that will watershed (see Figure 4-4 for the not make it to the tributary or pond. percent contribution by The trapping factor is primarily used subwatershed). for agricultural lands where a significant amount of soil erosion is As shown on Figure 4-4, expected to occur. However, not all of subwatersheds PBB, SPB, BFB, PBH that soil will reach a stream or pond and PBS contribute the largest due to low sloping land and natural quantity of phosphorus to the depressions that may exist and the Pennichuck water supply. These areas distance it must travel to reach there. correspond to some of the most Thus, the trapping factor allows an developed urban areas in the estimation of the amount of soil that watershed. Urban areas in the will not reach a tributary based on the watershed contribute higher distance from the nearest phosphorus loadings than the rural downgradient water body. A trapping areas due to the increased impervious factor is also applied to forested lands surfaces. The increase in impervious

Page 4-6 Pennichuck Water Works Watershed Management Plan 4.0 Hydrology and Nutrient Modeling Table 4-4. Eutromod Modeling Parameters Modeling Description Purpose Resource Parameter Land use Breakdown of land use categories in the watershed. Used in determining runoff coefficients and NRPC digitized mapping and aerial phosphorus to determine pollutant loadings. photographs (1994) Septic tanks All potential septic tanks within 200 meters of any of the chain To determine the total phosphorus contributed USGS (1985), NRPC aerial ponds. from septic systems. photographs (1994), and local town sewer locations Nutrient Phosphorus loadings contributed from the number of people living To provide a basis for estimating the total Reckhow, 1983 contribution in homes that potentially have septic systems. phosphorus contributed from septic systems. (kg/capita-yr) Nutrient soil Percent of phosphorus the soil is likely to bind and retain therefore To determine quantity of phosphorus from Estimated using Reckhow, 1983 & retention never reaching the pond. septic systems that will not reach the ponds. Reckhow, September 1990 Precipitation Average annual rainfall over a 30-year period. Used with runoff coefficient to estimate surface Pennichuck Water Works, Inc. (for runoff in watershed. Nashua area) Runoff Percent of precipitation resulting in surface water runoff based on To estimate surface water runoff for each Reckhow, August 1990 coefficient soils and land use. Estimated using percent impervious area for subwatershed to calculate total phosphorus urban land uses and soil type, slope and cover for rural land uses. loadings contributed from surface runoff. Phosphorus Dissolved (mg/l) and sediment bound (mg/kg) phosphorus Used with runoff coefficients and precipitation Reckhow, August 1990 loading concentrations based on specific land uses. to determine the phosphorus loadings for concentrations specific land uses within the watershed. Rainfall Erosivity A measure of the energy of rainfall and runoff which cause erosion Used in the Universal Soil Loss Equation State Soil Conservation Service (RE) (MJ-mm/ha-h). (USLE) which estimates soil loss for the sediment attached nutrient loading function. Soil Erodibility The average soil loss under specified conditions of hillslope length Used in the USLE (see above) State Soil Conservation Service (K) and gradient. Topographic Factor reflecting both area slope length and steepness. Used in the USLE (see above) Estimated using slope and length Factor (LS) data obtained from the State Soil Conservation Service Cropping Factor Factor describing the protective effects of vegetative cover, crop Used in the USLE (see above) State Soil Conservation Service (C) residues, tillage practices, and mulches. Erosion Control Describes efforts to control erosion through contouring and Used in the USLE (see above) State Soil Conservation Service Practice Factor terracing. Scaled zero to one, where 0 represents good practices and 1 represents poor practices. State Soil Conservation Service recommended using a value of 1.0 for the entire watershed. Pond Mean depth and surface area of ponds. Used to calculate detention time to help Pennichuck Water Works, Inc. Characteristics determine in-pond phosphorus calculations. (some values were estimated) Trapping The percent of pollutants contributed from surface water that is To estimate the quantity of phosphorus entering Estimated based on guidance from Efficiency trapped before entering a tributary or pond. Trapping efficiencies the pond so that in-pond concentrations may be Reckhow, 1990 are scaled zero to one. Zero assumes tributaries and/or ponds determined. receive all pollutants. One assumes that tributaries and/or ponds receive no pollutants.

Pennichuck Water Works Watershed Management Plan

4.0 Hydrology and Nutrient Modeling

Table 4-5. Land Use Areas Within the Pennichuck Watershed (acres) Residential (>1 acre) (>1 Residential (1/2-1 acre) Residential acre) (<1/2 Residential Condominium Parks & Town Owned Commercial Industrial Forest Orchard Crop Pasture Total Subwatershed Area (by Watershed of Percent subwatershed) PBS 0 354 0 23 40 43 47 778 0 0 0 867.84 5% PBB 0 300 107 0 34 0 785 1164 0 0 0 1949.48 11% PBH 116 268 23 0 90 65 81 846 0 9 9 1010.92 6% PBP 308 0 0 28 85 3 0 1333 159 31 31 1557.18 9% WBE 308 10 0 0 59 5 336 582 0 32 32 987.6 6% WBS 616 0 0 0 99 0 0 2328 75 37 37 2477.64 14% WBN 90100000175349000523.86 3% SPB 672665008212157000171.31 1% BFB 19 13 104 0 0 148 118 218 0 0 0 484 3% MB 450 0 0 0 401 0 0 1296 11 80 80 1465.9 8% Total 3390 1611 233 52 816 266 1554 9052 245 190 190 11495.73 Percent of Watershed (by land use) 19.3% 9.2% 1.3% 0.3% 4.6% 1.5% 8.8% 51.4% 1.4% 1.1% 1.1%

Table 4-6. Phosphorus Loadings by Land Use for the Pennichuck Watershed PBSPBBPBH PBP WBE WBS WBN SPB BFB MB Total lbs/yr lbs/yr lbs/yr lbs/yr lbs/yr lbs/yr lbs/yr lbs/yr lbs/yr lbs/yr lbs/yr Residential (>1 acre) 0 0 63 131 144 261 403 486 14 193 1695 Residential (1/2 - 1 acre) 330 280 250 05003201201197 Residential (<1/2 acre) 55 132 28 16 00001290360 Parks and Town Owned 1 1 13 5 17 28 0 2 0 48 114 Commercial 70 0 105 520032390424 Industrial 123 618 213 0 308 0 121 8 310 0 1700 Forest 12 19 10 38 11 74 12 3 4 43 226 Orchard 0 0 0 202 0 129 0 0 0 23 354 Crop 0 0 4 25 13 32 0 0 0 33 107 Pasture 0 0 4 24 11 34 0 0 0 35 108 Septic 0 85 0 18 0 0 0 253 0 0 356 Precipitation 121 81 0 56 0 0 0 21 0 0 278 Total 712 1215 691 519 511 558 536 1096 707 374 6919 Percent Contribution 10% 18% 10% 8% 7% 8% 8% 16% 10% 5%

Pennichuck Water Works Watershed Management Plan

4.0 Hydrology and Nutrient Modeling surfaces allows for more surface The chain pond system provides the water runoff, carrying any extra benefit of settling out some of contaminants that are deposited onto the phosphorus that enters the system these surfaces. As a result, developed so that the phosphorus loading going areas typically show a larger from one pond to the next is contaminant loading, as shown significantly less than if they were through the results of the model. entering the pond from a tributary and its surrounding watershed. This In-pond Phosphorus results in a lower phosphorus Concentrations concentration in Harris and Supply The model is also capable of Ponds since they are the last ponds in estimating the in-pond concentration the series. However, if these upper of the various ponds in the watershed watershed chain ponds fill up with based on the amount of phosphorus sediments and nutrients, their entering the pond and the volume of detention will water entering the pond over a be decreased If the chain ponds fill in with specific time period. The model and the sediments and nutrients, their sediments may considers the settling of phosphorus detention will decrease and the into the sediments in the pond to even become a sediments may become a develop an appropriate in-pond source of concentration. However, the model nutrients into source of nutrients into the does not consider internal phosphorus the drinking drinking water. loadings from the sediments that may water. Thus, it is occur during the summer months. important to This factor is discussed further in the maintain the capacity of these ponds recommendations section. and the ponds may have to be cleaned out when they approach capacity. In many surface water supplies there is one lake or reservoir with a In-pond concentrations were first surrounding watershed and the calculated for Pennichuck Pond and hydrologic and phosphorus Stump Pond, which receive water and contribution from the entire loadings from their tributaries and watershed are used to determine the surrounding areas. Based on the in-lake concentration. In the hydrologic budget, the average yearly Pennichuck watershed, there are a volume of water leaving these water series of ponds that make up the water bodies was used to determine the total supply, each capable of providing phosphorus loadings (in pounds) detention to remove some of the leaving these ponds and entering into phosphorus loadings. Thus, to more Holts Pond. Thus the in-pond accurately define the in-pond phosphorus concentration of Holts concentration for each pond, each Pond could be calculated with a better pond is looked at on an individual representation of pollutants entering basis to account for the detention that the pond and by taking in the effects is occurring. of detention that took place in the preceding ponds (Pennichuck and Stump Pond). Bowers, Harris and

Page 4-7 Pennichuck Water Works Watershed Management Plan 4.0 Hydrology and Nutrient Modeling

Supply Pond concentrations were level of 0.02 mg/l. This estimated then calculated in sequence using the concentration was calculated with same approach to include the effects consideration for the detention that of detention from their preceding each pond may be providing. As ponds. discussed above, if the ponds fill in with sediments and nutrients, this Results of in-pond concentrations are detention may be lost resulting in summarized in Table 4-7 with increased levels of phosphorus in comparisons made to 1996 average each of the ponds. The expected in- concentrations in Table 4-8. Since the pond concentrations with no added intake to the water supply distribution detention is also provided in Table 4- is primarily from Harris Pond, this 8. The results show a significant pond is the focus for maintaining a increase in phosphorus levels in each reasonable water quality phosphorus of the ponds. This data emphasizes goal. the added benefit the chain ponds have on phosphorus levels and As shown in the table, the phosphorus indicate the importance of concentration in Harris Pond during maintaining the pond capacity. an average year is estimated at 0.033 mg/l, which is comparable to the 1996 Although 0.02 mg/l is a desirable in- pond maximum for phosphorus in an Table 4-8. Comparison of Estimated Phosphorus Levels (with and unfiltered water supply, it is probably without detention) to Average Phosphorus Data for 1996 not realistically achievable or Pond Estimated Estimated Average affordable for the Pennichuck chain Modeled Modeled Sampled pond system because of the already Concentration Concentration Concentration urbanized nature of portions of the Considering if No Detention (1996) (mg/l) Detention from is Provided from watershed. A more realistic goal of the Ponds Ponds (mg/l) about 0.025 mg/l may be achievable (mg/l) using a combination of mostly low Stump Pond 0.073 0.073 0.01 cost prevention best management (based on only practices (BMPs) and higher cost one sample) remediation BMPsi. Pennichuck 0.028 0.028 No data Pond To reduce the in-pond concentration Holts Pond 0.046 0.056 0.05 to 0.025 mg/l, approximately 2,200 pounds of phosphorus will need to be Bowers Pond 0.039 0.047 0.12 removed from the watershed, upgradient of Harris Pond. Because it is a chain pond system, the quantity Harris Pond 0.033 0.049 0.04 of phosphorus removed from each subwatershed is important in terms of Supply Pond 0.029 0.099 0.03 the impact it has on the in-pond concentrations. For example, average of 0.04. This is about one and phosphorus removed from the one half times the desired phosphorus drainage area into Holts Pond not only impacts the in-pond

Page 4-8 Pennichuck Water Works Watershed Management Plan 4.0 Hydrology and Nutrient Modeling

Table 4-7. Modeled In-pond Phosphorus Concentrations and Parameters for Pennichuck Water Supply System - Existing Situation Stump Pond Pennichuck Pond Holts Pond Bowers Pond Harris Pond Supply Pond Lake area (km2) 0.08 0.23 0.09 0.37 0.32 0.06 Mean Depth (m) 1.52 1.52 1.22 1.83 4.08 3.60 Watershed area (km2) 6.14 17.38 57.35 64.57 69.61 70.27 Precipitation volume (10^6 m3) 0.09 0.25 0.10 0.41 0.35 0.07 Evaporation volume (10^6 m3) 0.05 0.13 0.05 0.21 0.18 0.04 Precipitation loading (kg/yr) 9 26 10 41 35 7 Land use phosphorus loadings (kg/yr) 488 381 1146 467 433 98 Land & precipitation phosphorus loadings (kg/yr) 497 406 1156 508 468 105 Phosphorus loadings from Merrimack River (kg/yr) 0.00 0.00 0.00 177.46 0.00 0.00 Phosphorus loadings from preceding pond(s) (kg/yr) 0 0 496 1334 1383 657 Total phosphorus loadings (kg/yr) 497 406 1653 2020 1851 763 Stream runoff (m/yr) 0.509 0.509 0.509 0.543 0.540 0.293

Lake volume (10^6 m3) 0.13 0.35 0.11 0.68 1.29 0.23 Detention time (years) 0.04 0.04 0.00 0.02 0.03 0.01 Volumetric waterload (10^6 m3/yr) 3 9 29 36 38 21 Total P-in (mg/l) 0.152 0.044 0.056 0.057 0.049 0.037 In-pond Phosphorus (mg/l) 0.073 0.028 0.046 0.039 0.033 0.029 P leaving pond (kg/yr) 238 258 1334 1383 657 N/A * Values are for existing estimated conditon.

Pennichuck Water Works Watershed Management Plan 4.0 Hydrology and Nutrient Modeling concentration of Holts, but also 4-9, which shows the allowable land impacts the in-pond concentration of use phosphorus loading into each downgradient ponds including pond to obtain these in-pond Bowers, Harris and Supply Pond. concentrations. However, the data Additionally, the majority of used to calculate these in-pond phosphorus enters Holts Pond directly concentrations was based on some through its tributaries, whereas the assumptions where data was missing, downgradient ponds receive most of such as mean depths or pond their loadings from the preceding capacities. Additionally, filling of the pond. ponds may result in the sediments contributing phosphorus to the water Based on this information, it is quality and could reduce the detention recommended that the majority of the provided. phosphorus be removed from the drainage area into Holts Pond Actual data is needed to verify the (including WBE through WBN and results of the model PBH) and from PBS, PBB, and BFB. to better define Approximately 2,200 pounds The more costly remedial measures specific sources of per year of phosphorus need to should be focused on PBS, PBB, phosphorus. Potential be removed from the watershed PBH, and BFB while the less pollution sources expensive preventative measures are based on database to achieve an in-pond more appropriate for the other searches and field concentration of 0.025 mg/l in subwatersheds. reviews are identified Harris Pond. in Section 5.0. Removal efforts are less of a priority in subwatershed PBP, MB and SPB (even though SPB was identified as one of the highest pollutant contributors) since the phosphorus i Best management practices (BMPs) loadings from these tributaries goes consist of activities that are used to through detention in Pennichuck and reduce the pollutant loadings entering the Stump Ponds and has a minimal ponds. BMPs may be regulatory in nature impact on the in-pond concentration or consist of structural measures to capture and treat stormwater before of Harris and Supply Ponds. discharge into the ponds or tributaries. However, low cost preventative Recommended BMPs for the watershed measures should be applied in these are discussed in more detail in the subwatersheds to minimize the recommendations section. loadings into these ponds.

Based on the theoretical modeling data, focusing efforts in this manner should help Pennichuck meet a water quality goal of 0.025 mg/l in Harris Pond. The concentrations that are likely to be achieved in each of the other ponds are summarized in Table

Page 4-9 Pennichuck Water Works Watershed Management Plan 4.0 Hydrology and Nutrient Modeling Table 4-9. Desirable In-Pond Phosphorus Concentrations and Parameters for Phosphorus Reduction in the Pennichuck Water Supply System Stump Pond Pennichuck Pond Holts Pond Bowers Pond Harris Pond Supply Pond Lake area (km2) 0.08 0.23 0.09 0.37 0.32 0.06 Mean Depth (m) 1.52 1.52 1.22 1.83 4.08 3.60 Watershed area (km2) 6.14 17.38 57.35 64.57 69.61 70.27 Precipitation volume (10^6 m3) 0.09 0.25 0.10 0.41 0.35 0.07 Evaporation volume (10^6 m3) 0.05 0.13 0.05 0.21 0.18 0.04 Precipitation loading (kg/yr) 9 26 10 41 35 7

Land use phosphorus loadings (kg/yr) 388 281 746 267 233 98 Land & precipitation phosphorus loadings (kg/yr) 297 307 756 308 268 105 Phosphorus loadings from Merrimack River (kg/yr) 0 0 0 177 0 0 Phosphorus loadings from preceding pond(s) (kg/yr) 0 0 366 938 1027 486 Total phosphorus loadings (kg/yr) 297 307 1122 1424 1295 591 Stream runoff (m/yr) 0.509 0.509 0.509 0.543 0.540 0.293

Lake volume (10^6 m3) 0.13 0.35 0.11 0.68 1.29 0.23 Detention time (years) 0.04 0.04 0.00 0.02 0.03 0.01 Volumetric waterload (10^6 m3/yr) 3 9 29 36 38 21 Total P-in (mg/l) 0.091 0.033 0.038 0.040 0.034 0.029 In-pond Phosphorus (mg/l) 0.049 0.022 0.032 0.029 0.024 0.023 P leaving pond (kg/yr) 162 205 938 1027 486 N/A *Values are projected to simulate conditions if phosphorus reductions are made.

Pennichuck Water Works Watershed Management Plan 5.0 Pollution Sources Section Contents

2. Nutrients, particularly nitrogen 5.1 The Pollutants------5-1 5.1 The Pollutants and phosphorus may enter 5.2 Pollution Sources ------5-2 waterways in high concentrations There is an extremely close from fecal wastes, fertilizers, and relationship between the water quality roadway runoff, providing food of a pond or reservoir and its for excess aquatic plant and algae watershed. The surrounding growth. Nitrogen and phosphorus watershed is responsible for are essential nutrients required by contributing the water required to plants to grow. Gardeners are maintain water levels and also probably familiar with the term contributes most of the pollutant “NPK” loads. Water quality is a direct (Nitrogen/Phosphorus/Potassium) reflection of watershed land use and since most fertilizers are based on hydrology. different ratios of these elements. Excess levels of the two primary The water quality threats in the nutrients, Pennichuck watershed were identified nitrogen and and prioritized based on their relative phosphorus are risks. These sources are the most typically found Water quality is a direct likely to interfere with the quality of in agricultural reflection of watershed Pennichuck’s supply. The general and urban runoff. categories of pollutants are High levels of land use and hydrology. summarized below: these nutrients can cause rapid 1. Microbiological contaminants, choking and particularly pathogenic clogging of waterways and protozoans such as Giardia and intakes, foul tastes and odors, and Cryptosporidium pose the accelerated filling-in of the ponds greatest threat to water quality and streams. Ultimately, this because they are so difficult to process (called eutrophication) treat effectively. Viruses and can interfere with the system’s bacteria, although more easily operability. Although all of these treated by disinfection, may also nutrients provide a food source pose a threat. for aquatic plants and algae, phosphorus is the nutrient of Typical sources of these highest concern in freshwater pathogens include livestock and systems. pets, sewer line breaks, cross connections to storm water The control of phosphorus is systems, and any other sources of extremely important because it is human and animal fecal waste. the “limiting nutrient” in a fresh With the exception of wildlife water system. Nitrogen, as with waste, which is typically phosphorus, may also result in insignificant (except for direct excess vegetative growth. waterfowl input) these factors are However, even if all waste usually linked directly with the sources of nitrogen were level of watershed development. eliminated, some plant species can fix nitrogen from the

Page 5-1 Pennichuck Water Works Watershed Management Plan 5.0 Pollution Sources

atmosphere and add to the result of runoff from disturbed or nitrogen pool if nitrogen is short eroding watersheds, waste in supply. Phosphorus is not discharges, aquatic weeds, algae usually available from the and products of their breakdown, atmosphere in large quantities so humic acids and other organic limiting the phosphorus supply compounds resulting from decay will theoretically limit the algae of plants, leaves, etc. in water blooms and other explosive plant sources, and high iron growth. concentrations. A watershed with land development activities, Nitrogen is also a nutrient of agricultural practices and concern. In its nitrate form, it has industrial effluents may cause a maximum contaminant level elevated turbidity levels in the (MCL) of 10 mg/l and is the most receiving waters. It is particularly commonly exceeded important to control turbidity MCL in groundwater levels in drinking water because systems. It is Limiting phosphorus supply elevated levels can interfere with typically contributed will theoretically limit the disinfection by sheltering to surface waters by microbes and reducing their algae blooms and other human and animal exposure to chlorination, wastes that are high explosive plant growth potentially allowing disease- in nitrogen and can causing pathogenic organisms to characteristic of usually be found in enter the distribution system. eutrophication. excess levels in

urban runoff. Even 5. Hazardous materials also pose a though exceedance significant threat. The sources of of the 10 mg/l limit is unlikely in these materials are as diverse as surface water, much lower levels the chemical compounds, ranging can still contribute to excess from petroleum hydrocarbons vegetative growth. entering from roadways or from

spills to essentially any chemicals 3. Sediments from disturbed areas, (industrial or otherwise) that other erosion, and road could be spilled in railroad or salting/sanding also are a threat to other transportation accidents. water supplies. In addition to the loss of storage capacity caused by these sediments, they also carry 5.2 Pollution Sources particulate contaminants such as Identification of the potential phosphorus, pesticides and heavy pollution sources in the watershed is metals into the water supply. one step in determining where Activities like construction that remedial and preventative measures disturb vegetation and natural soil should be focused to minimize profiles are major sources of contaminant impacts on the receiving sediment. water body. Once the locations where

these measures need to be applied are 4. Turbidity levels in water are identified, specific measures may then caused by the presence of be developed to meet water quality suspended matter. Water sources goals. typically become turbid as a

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Two types of pollution were A database search and a state file reviewed: point and non-point review were conducted through sources. GRANITNET to determine the locations of sites with known hazards. · Point Source Pollution is a source Sites from the Groundwater Hazard that enters waterways via a pipe Inventory (including automobile or is otherwise a defined salvage yards and underground “source”. storage tanks) and the National · Non-point Sources of Pollution Pollutant Discharge Elimination enter waterways with overland System (NPDES) permit databases runoff. They are too widespread were located. There were a number of to pinpoint as to exact source, e.g. Groundwater Hazard Inventory sites lawn fertilization is a non-point within the watershed, however, no source of pollution. automobile salvage yards or NPDES sites were identified through the Point sources of pollution were search. Figure 5-1 shows the location identified in the watershed through: of these and other potential pollution sites. 1. field surveys, 2. review of aerials, A file search was also completed 3. database searches, and through the NH Department of 4. a review of federal/state records. Environmental Services (NHDES) to determine additional sites that This review identified subwatersheds GRANITNET may not have that contain several pollution sources indicated. Conversations were held so that their relation to the overall with both the Groundwater Protection water quality of the pond system Bureau and Hazardous Waste could be further defined. Figures 5-1 Division of NHDES to help identify and 5-2 show all of the point sources potential threats to the water supply of pollution sources identified and an All Sites List was obtained (a through the above measures, plus list of all hazardous waste, leaking some non-point sources that are underground storage tanks, landfills, mappable. etc in the state) and reviewed. A list of sites found both during the state Point sources of pollution are usually file review and the database search directly piped, often require permits and their status is in Appendix F. and may include: Many of the sites found during the · Point sources covered by the search and file review are identified National Pollutant Discharge by NHDES as “backlog”, which Elimination System (NPDES) means that NHDES does not consider Permits them priority sites and a project · Point sources covered by manager has not been assigned yet. Groundwater Discharge Permits There are eight groundwater · State and Federal listed hazardous discharge permits within the waste sites watershed and five sites are ongoing and considered priority by NHDES. All other sites within the watershed

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have been remediated and/or closed. should not be a problem if they are Currently, the sites within the managed properly. watershed that are ongoing and assigned a project manager include: Many of these point sources of pollution are already being 1. Site #910623: Bellemore Heating remediated. Often, the largest Oil Co.; 21 Old Nashua Road, pollutant contributions are associated Amherst; Project manager: Willis. with non-point pollution. Measures currently in place that provide some 2. Site #861101: level of protection to the ponds are Several hazardous waste Merrimack Well #6 discussed in Section 6.0. These sites provide potential point (Merrimack include some of the preventative Industrial Metals); efforts the state, local authorities, and sources of pollution. off Milford Road, Pennichuck Water Works have Merrimack; Project incorporated to deal with non-point manager: Wickson. source issues.

3. Site #940966: Post Road Plaza; Non-Point (Stormwater) Sources Route 101A, Merrimack; Project Non-point sources include a wide manager: Wickson. variety of pollution sources that enter the water body through stormwater 4. Site #941134: Connell Shopping runoff from storm drains or overland Plaza; Rte 3, Merrimack; Project runoff and may include: manager: Berry. · Industrial and commercial land 5. Site #880316: Coca-Cola; 600 uses Amherst Street, Nashua; Project · Dense residential land uses Manager: Willis. · Intensive agriculture, including

nurseries and golf courses The RCRA (hazardous waste · Transportation activities generators) and provisional lists were · Construction activities also obtained from NHDES and reviewed to identify other potential · Landfills threats to the watershed. There are · Sand and gravel operations 112 sites within the watershed on the · Airports provisional list. The provisional list consists of one-time hazardous waste Non-point sources of pollution generators. Most of these sites are contribute bacteria, nutrients (mostly located along Route 101A and are not nitrogen and phosphorus), heavy included on the map since they metals, oil, grease, and many other probably do not pose a significant pollutants to the water supply through threat to the watershed. A copy of the runoff from stormwater. Although all provisional list and the RCRA of these pollutants are important, generators is included in the phosphorus was the focus of this appendix. Locations of the RCRA analysis because it is the most sites can be seen in Figure 5-2, important freshwater nutrient and is addresses are included in Appendix F. the most readily and frequently Small and large quantity generators modeled non-point source indicator.

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5.0 Pollution Sources

Further, phosphorus is typically the load. Conversely, relatively “limiting” nutrient in freshwater undeveloped subwatersheds have a systems. Other non-point sources of positive contribution to the reservoir. pollution are also critical but either do For example, subwatershed MB1 not lend themselves to modeling contributes 15% of the inflow but because of complex behavior only 5% of the pollutant load. (bacteria) or are difficult to model because of a lack of data on typical This subwatershed contributes little runoff values (metals). pollution but lots of water to the system, suggesting that pollution An important factor in determining prevention efforts may be more the threat of pollution from an area is appropriate in this area than the more the relative flow contribution each expensive remedial measures. Table subwatershed makes to the overall 5-1 indicates which subwatersheds system in relation to the overall should be focused on remediation and phosphorus contribution of that prevention. subwatershed. For example, subwatersheds that contribute only a Table 5-1. Remediation vs. Prevention small fraction of the total storm water Measures for the Pennichuck Watershed input may be less important than Subwatershed Hydrologic Phosphorus Focus of those that contribute a large fraction Load Load Efforts of the total storm water input. PBS-Pennichuck Low (5%) High (10%) Remediation

Brook to Supply Phosphorus contributions calculated Pond for this watershed are based on total PBB-Pennichuck High (16%) High (18%) Remediation pounds of phosphorus loadings and have already taken runoff into Brook to Bowers consideration in determining these Pond loads. Thus, the most important PBH-Pennichuck Low (6%) High (10%) Remediation subwatersheds are those that Brook to Holt contribute the greatest loadings. Pond Results of the two analyses have PBP-Pennichuck High (11%) Low (8%) Prevention shown that those subwatersheds with Brook to the greatest hydrologic contribution Pennichuck Pond do not necessarily contribute the BFB-Boire Field Low (2%) High (10%) Remediation greatest phosphorus loadings. In other Brook words, some subwatersheds MB1-Muddy High (15%) Low (5%) Prevention contribute little flow but lots of Brook pollution, suggesting that pollution WBE-Witches Low (5%) Low (7%) Prevention remediation efforts should be the Brook East focus in this area. For example, WBS-Witches High (28%) Low (8%) Prevention subwatershed SPB contributes only Brook South about 6% of the total inflow to the WBN-Witches Low (6%) Low (8%) Prevention reservoir but an estimated 16% of the Brook North phosphorus load because of urbanized SPB-Stump Pond Low (6%) High (16%) Prevention land use. Similarly, subwatershed Brook BFB contributes about 2% of the flow but nearly 10% of the phosphorus

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Although SPB is identified as a major In addition to typical airborne contributor of pollution, it is not particulates and pollutants that collect identified as a priority for remediation on impervious surfaces, industrial efforts. This is due to the detention sites may also contribute other forms that Stump Pond and the other ponds of pollutants such as hazardous in the chain provide before the materials. For example, if a spill pollutants reach Harris and Supply occurs during dock loading and Ponds. Results of the modeling show unloading and is not contained and that removal of phosphorus in SPB cleaned immediately, residual will not have a significant impact on contamination may introduce the water quality in Harris or Supply contaminants into stormwater during Ponds. However, as the ponds fill in, rain events. There may also be this detention will be minimized and contaminants from stack emissions. more pollutants will reach the intake, at Dense residential land uses which point remedial Potentially large contributors to Prevention efforts are efforts may be pollution are sewered and unsewered typically much lower cost necessary at SPB. dense residential and commercial This points out the than remediation efforts. areas close to the ponds and importance of tributaries. Each of the towns was prevention efforts, contacted to help identify which areas which are typically of the watershed are sewered (Figure free or very low cost as opposed to 5-3). All of Nashua and expensive remediation efforts. approximately 42% of the roads in

Merrimack that fall within the Specific non-point pollution sources watershed are sewered. Neither Hollis identified in the Pennichuck nor Milford have any roads that are watershed are provided below along sewered within the watershed. with the threats they pose to the Amherst does not have a sewer reservoir. system, however, Route 101A, which has commercial areas is sewered (this Industrial and commercial land comprises approximately 10% of the uses Amherst portion of the watershed). Industrial and commercial land uses Sewered and non-sewered areas are contain potential sources of pollution differentiated because they represent due to the larger impervious areas that different types of threats. contribute greater stormwater surface runoff. Impervious areas increase the Unsewered residential areas rely on volume and velocity of flow. Water individual septic systems for can not infiltrate into the ground so wastewater treatment. Significant sediment and attached pollutants in water quality problems have been this flow are increased. These sources associated with septic systems if there generally also have a stormwater is a lack of adequate soil for treatment collection and discharge system that and/or high ground water levels carry stormwater and its pollutants and/or shallow depth to bedrock. directly to a tributary or pond. Septic systems located closer to Pennichuck’s water supply have a

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5.0 Pollution Sources greater chance of contributing which in turn increase the surface microbiological contaminants such as water runoff and pollutants carried bacteria and viruses and nutrients into the Supply Pond chain. such as nitrogen and phosphorus through entrainment in runoff (in Intensive agriculture cases where there is a breakout of Agricultural farms and animal waste effluent on the ground surface), or also contribute pollutants to the through the contribution of watershed. The land use types of contaminated groundwater baseflow concern include nurseries, golf to the ponds. courses, and farms. These sites were

identified because of the potential Other concerns include bedrock threat of pollutants outcrops or areas with a lot of stones, from animal wastes steep slopes, and low lying areas or the application of exhibiting signs of influence of Densely populated pesticides and surface water runoff. These areas may fertilizers. These commercial and residential adversely affect the functioning of the applications may systems, increasing the chance of areas may contribute result in the pathogens entering the system. This is significantly to water discharge of a typical problem in older microbiological quality problems. “grandfathered” systems, but is contaminants, usually not a significant concern in nutrients, and toxic newer systems that now meet materials that could lessen the quality standards that are more rigorous. of the water supply. Pets in dense

residential areas also have the Densely populated commercial and potential to increase microbiological residential sewered areas, as seen in contaminants and nutrients to the Nashua, often contribute significantly reservoir. Agricultural uses in the to pollution to a watershed. Possible watershed are indicated on the sources of pollution in sewered areas pollution sources map, Figure 5-1. include large impervious areas, Also included on this map are areas contamination from automobiles, where there is known pesticide use. possible breaks in sewer lines, There are no golf courses or nurseries intensive / excessive lawn care in the watershed, however, there may practices, car washing (both be in the future. commercial and home), and pet wastes among others. Together, these Transportation activities potential pollution sources typically contribute significant levels of Transportation spill risks in each of bacteria and nutrient loadings to the the towns were also identified. receiving water body by direct Transportation spills are most likely overland runoff or through to come from the roadways or stormwater collection systems. railways that intersect a tributary to the water supply or the supply itself. Densely populated areas such as the Another source is airports. If a spill residential areas in Nashua, are occurs at these locations, there is little considered a more significant threat, time to take remedial action before it due to increased imperviousness enters the supply. The major roadway

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and railways in the watershed that increase the imperviousness of the crossed Pennichuck’s system include watershed and add many non-point the Daniel Webster Highway, the source pollutants. Everett Turnpike, and Routes 101A and 122. Each of these roads traverse In addition to spill risks, most a significant portion of the watershed roadways may also contribute general and cross Pennichuck’s system at non-point source pollution including more than one point. Spills at any of nutrients, heavy metals, oil and these locations may result in grease, and sediments from roadway hazardous materials coming in direct sanding and salting. contact with the receiving waters with Construction activities little time to react to Construction activities are considered Construction activities may contain or remediate potential pollution sources due to the the incident. bring significant sediment potential for erosion and loads, with many attached sedimentation. The land clearing Airport maintenance during construction activities leads to pollutants, into the water facilities generate reduced canopy cover from trees, pollutants such as supply. resulting in rain directly contacting aviation fuel waste the soils, which increases stormwater oil, hydraulic fluid, runoff volume and velocity. Erosion cleaning lubricants, and degreasing is the result. Smoothing of land solvents. Fuel trucks often refuel the surfaces, compaction, increased planes at the loading gates and impervious areas, and filling of overfills are a common problem. In wetland areas all combine to increase colder months, deicing chemicals are the amount of surface runoff. used for safety on the runways, often Therefore, suspended sediments and with chemicals that contain urea, a attached nutrients are transported to nitrogenous compound that could the streams. contribute to the eutrophication of

surface waters. To control plant and weed growth, pesticides and

herbicides may be used on the grounds surrounding the runways. Storage areas for petroleum products, solvents, pesticides and road salt are also a potential threat to surface water quality. The Boire Field Airport in Nashua is located in the BFB subwatershed, so there is potential for some of these activities to contribute to the pollutant load.

Residential roadways are not included because large commercial trucks transporting hazardous materials are not expected to travel on these roadways. However, the roads do

Page 5-8 Pennichuck Water Works Watershed Management Plan Section Contents 6.0 Existing Protection 6.1 Regulatory Protection ------6-1 6.2 Town Wide Land Use Controls Measures ------6-3 6.3 Land Ownership...... 6-15 6.4 Pennichuck Water Works .6-15 In addition to the regulatory impervious areas, such as 6.5 Town Ownership ...... 6-16 measures discussed in Section 3, commercial and industrial areas, are 6.6 Other Protective Measures6-17 there are many existing protection expected to contribute more measures in place by Pennichuck stormwater runoff, which in turn Water Works and the local results in a degradation of water municipalities. This section provides quality due to the pollutants carried information on: in the stormwater. Thus, areas zoned conservation will provide more · local regulatory controls protection than areas zoned including land use controls, industrial. · regulatory controls, and The most desirable zoning is · land ownership, and other conservation since it minimizes the protection measures. impervious fraction of land and buffers the ponds from stormwater Additionally, the chain pond system pollutants. Next is low- lends natural protection to the water density residential quality of the ponds by allowing zoning (>2 acre lots) pollutants to settle out through the which is also relatively The chain pond system natural detention that is offered. desirable from a water provides the best Unfortunately, this source of quality standpoint, since protection has decreased as the ponds the impervious area is protection through natural fill in and sediments may eventually kept to a minimum. As detention. Open space, become a source of pollution. residential zoning forested lands and low becomes more dense 6.1 Regulatory (less than one acre lots) density residential zoning Protection water quality impacts also provide some tend to increase from protection. Local regulations help protect the more cars, more roads, Pennichuck watershed by controlling more pets and other land use activitie s and limiting sources of waste material. The least development in the watershed. desirable zoning classifications are Controls include zoning bylaws and commercial and industrial, as these ordinances, subdivision regulations, tend to have large parking lots and site plan reviews, and protection greater amounts of impervious areas overlay districts. resulting in large contributions. They also tend to produce the largest Zoning amounts of “unfiltered” storm water. Zoning can be a useful protection measure by controlling the future Zoning information was automated to development of specific areas. The produce a composite zoning map for degree of protection zoning provides the entire watershed (Figure 6-1). is directly related to the type of Zoning information from the five zoning allowed within the watershed. cities/towns was aggregated into the For example, land uses with large following categories: residential A (>2 acre lots), residential B (1/2 - 2

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acre lots), residential C (< 1/2 acre places subject to flooding, poor lots), planned unit development, drainage, or other hazardous commercial, industrial, agriculture conditions. and business, residential and One way subdivision regulations can agriculture, and recreational. help protect natural resources is by encouraging cluster development, Zoning can provide a good overview which requires the use of open space, of the watershed and signifies decreasing the amount of impervious buildout conditions, but in order to area and as a result, will also determine more effectively the area decrease stormwater pollution. of protection already in place within Another method is to require that the watershed, current planning post-development groundwater restrictions can affect the outcome. recharge be equal to or exceed For instance, when industrial and predevelopment discharge. residential zoned lands are slated for Provisions included in the development, concessions to provide subdivision regulations for each of buffers or other restrictions may be the towns is discussed in more detail sought by local Boards, since the below. impacts on the environment and Site Plan Review infrastructure may be Subdivision regulations Site Plan Reviews offer a different significant. type of protection. Site Plan Reviews can encourage cluster are required for any significant development, which tends Subdivision development in all towns of the Regulations to minimize watershed. The intent is to encourage Subdivision a desirable and compatible character imperviousness. regulations play an of development within the towns. important role in Most of these center on residential providing protection for the development and require an watershed. They are enacted to environmental impact study prior to protect the safety, convenience, and construction. In most cases Site Plan welfare of the inhabitants of the Reviews require that developments towns they relate to. Although they provide adequate provisions for are not specifically geared towards environmental factors such as protecting the water supply, many pollution, odor, noise, and the limit septic system use and/or protection of natural features and development within areas of poorly sediment and erosion control. drained soil; some require an Adequate provisions for solid waste environmental impact review; many and wastewater disposal are also require open space in any new required. developments, reducing the amount of impervious areas; stormwater Protection Overlay Districts runoff and drainage is tightly Protection Overlay Districts provide monitored; and in many cases, specialized protection of wetlands, developments are not allowed in floodplains, water supplies, aquifers

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6.0 Existing Protection Measures and/or watershed protection. Each o Within its residential districts, town within the Pennichuck Milford requires larger minimum watershed has specific overlay lot sizes where there is no access districts that provide additional to public sewer. Lot sizes are protection for critical areas and/or also required to be larger where resources within their towns. Where there are more severe soils. land in the watershed falls under There are additional regulations these overlay districts, the protection regarding setbacks to the town may be increased. wells, however, there are no additional setback requirements Septic Systems for other bodies of water. Septic systems are potential pollution o The Town of Hollis does not threats, but if maintained properly, allow the placement of septic and set back from surface waters, the systems within 75’ of the edge of risk is significantly reduced. Both a public body of state and local septic system water or from a well. They also regulations are written to ensure this The undeveloped land protection. Current septic system require that soils regulations within all the towns do are adequate to surrounding the water not allow septic systems in handle individual supply provides a natural inadequate soils. Some of the older septic systems. septic systems however, may be o Nashua has a buffer. ineffective, particularly for minimum lot size commercial / industrial use or in requirement of 40,000 square densely populated or shoreline areas. feet where individual septic systems are proposed. The NH Code of Administrative Rules, Env-Ws 1008.03 states that 6.2 Town Wide Land the minimum setback distance of a septic tank from surface water must Use Controls be 75’. In addition to this each town The zoning and subdivision has additional regulations regarding regulations of each city/town were the use of septic systems. reviewed to determine the amount of protection provided through each of o Amherst, Milford, and Hollis all the cities/towns that make up the require approval of the NH watershed. A review of the land use Water Supply and Pollution and zoning maps (Figures 2-2 and 6- Control for any proposed septic 1 respectively) reveals that much of system. the watershed is currently vacant or o Merrimack’s zoning ordinance residentially developed (>2 acre lots) states that all septic systems must and/or zoned land. In addition, much be placed on the least severe of the land surrounding the water soils on the lot. Also, septic supply is owned and protected by systems cannot be located less Pennichuck Water Works, providing than 20’ from any property line. a natural buffer between the water

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supply source and the developed o There is one stream within areas of the watershed. However, a Milford that travels to the water review of the zoning map reveals that supply. The land surrounding it considerably more dense is zoned residential 1/2 to 2 acre development could be allowed lots and is sparsely populated at through much of the watershed in the this time. future. Each of the towns’ specific Table 6-1 shows the percentage of regulations is discussed in more each zoning designation in the detail below. watershed along with the level of potential protection it provides. The Amherst land directly abutting the ponds, Amherst divides its zoning bylaws brooks and streams are the most into 13 types; Aquifer Conservation susceptible to District, Commercial Zone, Flood pollution that leads Plain Conservation District, General to poor water Amherst requires that all Office, Historic District, Industrial quality. Zone, Limited Commercial Zone, drainage must be carried Northern Rural Zone, Northern to existing watercourses. o In Merrimack, Transitional Zone, Planned Office roughly 43% Development, Residential/Rural of the land Zone, Wetland Conservation District, abutting the water supply is and Watershed Protection District. residential >2 acre lots, 36% is The land within the Pennichuck zoned industrial, and 21% is watershed is zoned as zoned commercial. Residential/Rural, Industrial, and o In Nashua, 47% of the land Commercial. abutting the ponds and streams is zoned residential 1/2 - 2 acre Subdivision Regulations lots, 11% is zoned residential <1/2 acre lots, 36% is zoned o Any new development requires a industrial, and 6% is zoned review of the impact on the commercial. environment and water supply. o In Hollis, the land directly o Any proposed septic system abutting the ponds are zoned as requires the approval of the NH recreation, the lands surrounding Water Supply and Pollution the streams are zoned residential Control. and agriculture or residential > 2 o Alteration of any natural man acre lots. made water course requires the o A small portion of Witches approval of the NH Special Spring Brook travels through an Board or Zoning Board of industrial zoned area of Amherst. Adjustment. Stump Pond and its tributaries o Open space may be required in are surrounded by residentially the residentially zoned areas of zoned areas > 2 acre lots. town. There is a provision within the subdivision regulations that

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Table 6-1 Zoning Designations Zone Percent of Level of Protection Watershed Residential - > 2 acre lots 30 Less dense residential lots provide less impervious areas for runoff to flow over. Of the three residential zones, this one is most preferable. Residential - 1/2 - 2 acre 6.4 Residential zoning is preferable over industrial and lots commercial due to the amount of impervious area provided. The less dense the lots, the better the protection. Residential - < 1/2 acre 3.1 Both dense residential and planned unit development lots areas have a greater amount of imperviousness than Planned Unit 1 other residentially zoned areas. Since there is Development relatively little dense residential zoned areas in the watershed, these not pose a significant threat at present. Recreation 2.4 Recreational uses often come with vast areas of open space or forest, which provide a buffer for potential pollutants to travel through prior to reaching the streams. Residential/Agriculture 31.5 Residential agricultural land is the highest zoned area in the watershed. This zone provides some protection in that the residential lots cannot be less than 2 acres. If agricultural lands are well maintained and best management practices are used, this land will provide a good amount of protection. Agriculture/Business 0.1 This land probably does not pose a significant threat because there is so little of it in the watershed. The zone is located in Hollis, on the border of Amherst. As it is not located adjacent to any streams the level of protection is good. Commercial 3.2 Commercial and industrial lands provide little protection in the watershed. Impervious areas tend to be great, increasing the volume and velocity of runoff to the streams. State and local regulations provide some protection from industries and commercial areas, but the overall impact tends to be negative unless significant measures to reduce imperviousness and Industrial 18 infiltrate stormwater from roofs and parking lots are taken.

Pennichuck Water Works Watershed Management Plan

6.0 Existing Protection Measures

states that if the Board deems it of the tract is required for open essential, a final plan must show space. an area of open space, not to o Mobile homes are allowed in all exceed 15% of the total area of residentially zoned areas. the land. o A “right to farm” ordinance is o Drainage must be carried to included to protect farms and existing water courses. farming. Farming is permitted in o Excavation of soils is allowed all residentially zoned areas. with a permit in any district o Non-Residential Site Plan except the Historic District and Reviews require adequate the Wetlands Conservation provisions for environmental District. factors such as pollution, odor, o Special Exceptions to the noise, and the protection of regulations are permitted as long natural features. Adequate as the proposed use will not provisions for solid waste and adversely affect the groundwater wastewater disposal are also of Amherst, particularly in the required. Aquifer Conservation District. Uses permitted by special Zoning Bylaws / Protection exception include religious, Districts nursing homes, elderly housing, multi-unit housing, private Floodplain Protection District: schools, hospitals, outside Permitted uses within the Floodplain storage of equipment and Protection District, which do not result in the erection of any structures materials, outside recreation, include: minor fences, docks, professional offices, funeral wharves, and boathouses; agriculture; homes, sawmills and kennels. o All land to be subdivided must forestry; recreation; golf; parking be adequate for building without lots; driveways and roads; or other endangering the public health, recreational use such that it does not safety or the environment. contribute to pollution of ground or surface water; damage or destroy o Land subject to flooding, poor habitats; or disturb or reduce the drainage, or other hazardous natural cleansing features of the conditions cannot ordinarily be wetlands, streams, and floodplain subdivided. o Land inadequate for sanitary areas. sewage disposal cannot be subdivided. Wetland Regulations: Wetlands are o The preservation and protection identified as poorly drained or very poorly drained soils. The intent of of existing natural features this regulation is to prevent the should be given due regard. development of buildings and land o Planned residential developments allow for somewhat denser use on naturally occurring wetlands development than would which would contribute to the otherwise be allowed. Open pollution of surface or ground space is encouraged, at least 40% waters; and to prevent the destruction

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of natural wetlands which provide Aquifer Conservation District: This flood protection, recharge of is to provide for the protection of the groundwater supply, and water resources from contamination augmentation of stream flow during by polluting hazardous, or toxic dry periods. No wetland may be used materials. The discharge of to satisfy minimum lot requirements; hazardous or toxic waste from no septic tank or leach field may be industrial and commercial buildings located closer than 75' to any is prohibited. Other prohibited uses wetland; and no structure shall be include the outdoor storage of salt or located within 50' of a wetland. deicing chemicals; solid waste or septage disposal sites; automotive Water Pollution Control Regulations: repair shops; junkyards; on-site These regulations are provided to storage of hazardous or toxic prevent pollution in the water supply, materials; residential USTs; and surface and ground waters of the filling stations or gas stations. town by inadequate sewer or waste Monitoring wells must be installed disposal systems. No buildings with and tested for compliance with on-site discharge Drinking Water Standards monthly are allowed on industrial and commercial Hollis requires that all new without prior properties. The Board of Health subdivisions have approval from controls the use of pesticides, the town, and the herbicides, fertilizers, etc. No more provisions for NH Water than 70% of any lot may be rendered sedimentation and erosion Pollution Control impervious within this district. control. Commission. Procedures for Hollis test pits, perc Hollis divides its zoning bylaws into tests, filling, installation and other 11 different districts, the Agricultural specific requirements are included in and Business Zone, Flood Plain, these regulations, which are stricter Historical Center Zone, Industrial than state regulations. Zone, Mobile Home Zone, Recreational Zone, Residential and Watershed Protection District: This Agricultural, Rural Lands Zone, district is provided to control Trailer (Mobile Home) Park Zone, building and land use to prevent Water Supply Conservation Area, pollution of surface and ground water and Wetland Conservation Areas. and to prevent the destruction of watershed areas that provide flood The la nd in the Pennichuck protection, recharge of groundwater watershed is zoned as Rural Lands, supply or stream flow during dry Residential and Agricultural, periods. No septic systems and no Agricultural and Business, and buildings are allowed to be Recreational. constructed within the watershed protection district.

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Subdivision Regulations commercial areas used for commercial purposes shall o All subdivisions require a Site occupy no more than 50% of the Plan Approval with provisions lot upon which they are located. for erosion and sedimentation Twenty percent of the total lot control. area must be landscaped open o Drainage must be carried to space. No outdoor storage of any existing watercourses. material shall be permitted, o Open Space and Planned except within enclosed Development is included to containers and/or visually provide for a more efficient use screened areas. of land while protecting existing o A recreational zone exists within and potential water supplies, and 600' of the shores of Silver Lake, while promoting the preservation Pennichuck Pond, and Rocky of open space, farmla nd, Pond. This zone is recreationares, green space, intended to allow fields and woods, valuable residential and wildlife habitats, and natural and recreational Hollis subdivision historic features. development around regulations call for o Soils must be adequate to handle local bodies of water stormwater to be carried to individual septic systems. while protecting water o Excavation is prohibited within quality and the existing watercourses. the water supply conservation, recreational aspects of agriculture and business, the area. Permitted uses include recreational, historical, trailer single and two family dwellings; park and mobile home districts. farming; open space and planned Excavation is also prohibited development; condominiums; where it would pose a threat to a and home occupations. Publicly known major water supply; and owned parks, playgrounds, golf beneath or adjacent to inland courses, pools, and libraries as surface waters such that state and well as privately owned golf federal agencies require a permit. courses; country clubs; pools; o Uses permitted in the Mobile tennis courts and fishing lakes Home Zone, other than mobile and clubs are acceptable with a homes, are farms, the sale of Site Plan Approval from the farm products, stables, Planning board within this subsidized housing for the district. elderly, open space and planned development, condominiums, Zoning Bylaws / Protection and home occupations. Districts o Any development for the elderly must be within one mile of the Open Space: Buildings in the Town Monument. industrial and commercially zoned o Land along Silver Lake Road and districts cannot occupy more than Ames road is zoned Agriculture 50% of the lot they are located on. and Business. Buildings in the

Page 6-7 Pennichuck Water Works Watershed Management Plan 6.0 Existing Protection Measures

Floodplain Protection District: metals and ores; synthesis or Assurance must be provided to the blending of artificial or natural Building inspector that water and fertilizers; and stockyards and feed sewer systems are designed to lots. No waste may be stored which minimize or eliminate infiltration of may cause the leaching of chemicals flood waters into the system or or other pollutants into the discharge of wastes into the flood surrounding water table or surface waters. On-site disposal systems runoff, or the emission of toxic or must be located to avoid impairment harmful gases within these areas. to them or contamination from them Fluid discharges from the plants must during periods of flooding. Section be adequately treated so as not to 404 of the Federal Water Pollution pollute the surrounding water table or Control Act must be complied with. surface runoff. Prior to the alteration or relocation of a watercourse, the Wetlands Board of Wetlands: Structures and fill the NH Department of activities are prohibited in wetland Environmental Services must be areas. No septic tanks or leach fields notified. are to be located within 75' of a wetland boundary. No residential, Along watercourses with a designed commercial, or industrial use will be Regulatory Floodway no allowed that requires the filling of encroachments, including fill, new wetlands. construction, substantial improvements, or other development Water Supply Conservation District: are allowed within the floodway that The only uses permitted in this zone would result in any increase in flood are single family dwellings, forestry, discharge. and wildlife refuge. No septic tank or leach fields are allowed within 150' Industrial: Prohibited uses in the of a wetland or other standing water. Industrial Zoned districts include: abattoir operations, any use which Aquifer Protection Zone: This is an consumes large quantities of water or overlay intended to protect, preserve, which requires special waste and maintain existing and potential treatment; cremation; electroplating; ground water supply and ground industrial fermentation; kiln firing or water recharge areas. Prohibited uses drying of materials other than wood; include the handling, treatment, leather tanning or processing; storage, and disposal of hazardous manufacture, compounding, or wastes; subsurface storage of processing of chemicals; petroleum; disposal of solid waste or manufacture of charcoal; liquid or leachate wastes; storage of manufacture or compounding of road salts; dumping of snow; solvent, water or oil based paints, commercial animal feedlots; varnishes or coatings; petroleum or excavation of sand or gravel; auto tar refining or processing; recycling repair shops or junk yards. of metals, organic, or inorganic chemicals; smelting or melting of

Page 6-8 Pennichuck Water Works Watershed Management Plan 6.0 Existing Protection Measures

Merrimack of the intersection of Daniel Merrimack divides its land into 12 Webster Highway and Baboosic zones: Residential District, Limited Lake Road east of the turnpike. Commercial District, General Public water and sewer must Commercial District, Industrial serve dwelling units. District (3 types), Wetland o Planned Residential Conservation District, Flood Hazard Developments are intended to Conservation District, Elderly allow higher density housing in Zoning District, Planned Residential areas where public water and District, Aquifer Conservation sewer are available. Provisions District, and the Shoreland Protection are included for environmental District. factors such as pollution, Within the Pennichuck watershed, noise, odor and Merrimack requires the protection Merrimack is divided into stormwater from closed Commercial, Residential, and of natural land Industrial Districts. features. No pipe structures to flow septic systems along a grassed swale Subdivision Regulations are allowed in these districts. before discharging to a o A Site Plan Review is required o Underground wetland or water body. for all developments other than a storage tanks single residential dwelling. are prohibited o Cluster Residential in all areas unless suitable Developments are used to secondary barriers and automatic promote the conservation of the alarm systems are provided. natural environment, and to o Excavation is permitted pursuant promote uses in harmony with to Chapter 155-E Sections 1-11 the natural features of the lands. inclusive of the NH Revised Wetland and flood plain areas are Statutes Annotated. not to be included as buildable o Proposed individual septic acreage within this district. systems require approval from Public water and sewer must the NH Water Supply and serve all dwellings within this Pollution Control Commission. zone. Provisions are included Septic systems must be located that require the protection of the more than 20' from the property environment from factors such as line and placed on the least pollution, noise, and odor. severe soil on the lot. o Mobile home parks are allowed o Closed storm drainage systems in any residentially zoned with an outfall into a wetland or district. water body are required to flow o Elderly housing must be located along a grassed swale prior to within 1 mile from the outfall. intersection of Daniel Webster Highway and Baboosic Lake Road, or within a 2-mile radius

Page 6-9 Pennichuck Water Works Watershed Management Plan 6.0 Existing Protection Measures

Zoning Bylaws / Protection Aquifer Conservation District: The Districts purpose of this district is to protect and preserve the existing Shoreland Protection District: This groundwater supply and recharge district includes all land located areas of the town. Industrial and within 250' of the reference line of commercial uses are allowed surface waters including but not provided no on-site discharge occurs. limited to Bowers Pond, Holts Pond, Prohibited uses include the disposal Harris Pond, Pennichuck Brook, and of solid, liquid and leachable wastes; Pennichuck Pond. Prohibited uses USTs within 1000' of an existing include salt storage sheds, junk municipal well; outside storage of yards, solid or hazardous waste road salt; snow dumps; commercial facilities; the use animal feed lots; mining of land; on- of fertilizer; bulk site despoil or processing of storage of In Merrimack, the hazardous waste; auto repair shops or chemicals; sand junk yards; underground brush or developer is responsible and gravel stump dumps; trucking and bus excavations; and terminals; airports; and car washes. for paying for all snow dumps. downstream drainage All subdivision proposals and site plan reviews must be reviewed by the improvements necessary Where existing, planning board to assure that the for handling the additional natural woodland proposed use is consistent with the buffers must need to protect the groundwater and flow of the drainage from a remain within 150' the sewer systems are designed to subdivision. of the reference minimize or eliminate leakage or line (high water discharges from the system. The mark). The Conservation Commission is also leaching portions of septic systems required to review developments should be set back from the reference within the Aquifer Conservation line at least 75'-125' depending on District. the soils of the area, whether or not there is a natural woodland buffer. This District was recently modified Erosion and Sedimentation Control is in terms of area covered and required in the district; disturbance of restrictions. New regulations are a contiguous area greater than 50,000 currently in process. square feet requires a permit from the NH DES. New lots with on-site Junkyards: New junkyards are water or sewage must have a prohibited unless provision is made minimum frontage of 150' from the for monitoring wells of surface and shoreline whether or not there is a subsurface groundwater for woodland buffer. No building shall hazardous waste and/or toxic be located within 50' of the shoreline. substances. Impervious areas cannot exceed 20%. Agriculture uses are permitted Wetland Conservation District: No provided best management practices construction is allowed within the are conformed to. district. Permitted uses include

Page 6-10 Pennichuck Water Works Watershed Management Plan 6.0 Existing Protection Measures forestry; agriculture; water Subdivision Regulations impoundments; drainage ways; o All subdivision proposals will conservation areas; parks; wildlife undergo a planning board review refuges; open space; streets and and require an environmental utility rights of ways if necessary. impact statement. o Flood Hazard Conservation District: A soil erosion and sedimentation control plan is required for all Restrictions in Zone A flood area site plans and subdivisions. include prohibiting construction and o Any proposed septic system the use of fill that would cause any requires approval from the NH increase in the base flood level. The Water Supply and Pollution removal of soils is prohibited. All Control Commission. Adequate industrial chemicals or hazardous materials located in the A zone shall information must be provided to ensure that soils are suitable to be stored in flood proof containers or handle a septic system. stored at elevations higher than the o In developments where septic 100 year flood. Those located in the systems are proposed, a soil B zone should be stored at elevations scientist is required to determine higher than the 500 year flood the suitability of the soils. A elevation. 4000 square foot designated Open Space: No more than 50% of leachfield area or an area two times the required size must be the land reserved as open space shall reserved on each lot. Leachfields be wetlands or swamp areas. There is must be set back 100' from any also a section within the ordinance water body. that encourages the preservation of o The alteration of any natural or existing features. man made water course requires Milford approval from the NH Special Board or Zoning Board of Milford is divided into 7 districts Adjustment. with 3 overlay districts. The seven o The board may require a park districts include Residence A, (open space) before approval of a Residence B, Residence R, plan if it deems it necessary. Commercial, Industrial, Limited o High Intensity Soil Maps are Commercial, Integrated required to be provided for Commercial/Industrial District. The wetland, septic, or drainage overlay districts include the Aquifer reasons. Protection District, the Wetland o A permit is required for the Protection District, and the removal of earth on any lot. Floodplain Management District. o Mobile home parks are allowed Land within the watershed in Milford where adequate water and sewer is Zoned as Residence A, and facilities exist. Residence R.

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Zoning Bylaws / Protection the land. These are permitted in Districts residentially zoned areas of the town. Cluster developments must be Special Flood Hazard Areas: All constructed on land at least 5 acres in development proposals will be size if both municipal water and reviewed to determine whether such sewer are available and on at least 20 proposals will be reasonably safe acres of land if both municipal water from flooding. and sewer are not provided. In no case is the minimum lot size required Residentially Zoned (A&B) - Uses less than that necessary to ensure specifically prohibited in the adequate sewage disposal and water residentially zoned areas include supply according to natural site manufactured housing, solid waste conditions of soil type and slope of disposal sites, junk yards, and land. At least 50% of the total tract communication towers. Lots not area must be reserved as common serviced by both open space. municipal sewer Milford requires that in the and water must Aquifer Protection District - This Aquifer Protection District, have a minimum district is provided to protect, area of 40,000 the onsite discharge of preserve and maintain the existing square feet or and potential groundwater supply and stormwater be maximized larger depending groundwater recharge areas within on soil and slope the town; to conserve the natural through leaching catching conditions. basins, piping and resources of the town; and to prevent pollution of the environment. Many detention ponds. Open Space - uses are prohibited in this district Open space is such as: disposal of solid waste; required except for disposal of liquid or leachable waste, in single family and two family discharge of contact type process dwellings. At least 30% of a lot area waters on-site; outside unenclosed must be deemed open space. storage of road salt; dumping of snow containing deicing chemicals; Residential R - Uses excluded in this commercial animal feedlots; on-site section are the processing of natural disposal or processing for recycling resources and junk yards. The of hazardous or toxic materials or purpose of this zone is to provide for liquids; junk yards; filling stations; scattered, low-density development, and tank farms storing petroleum primarily residential and/or and/or toxic materials. agricultural. All subdivision and site plan approvals are contingent upon Cluster Open Space Developments - consistency in protecting the The intent of these developments is groundwater of the town and to promote the conservation of the adjacent communities; sanitary natural environment and the sewers are designed to minimize or development of community uses in eliminate leakage or discharges from harmony with the natural features of the system; on-site waste disposal

Page 6-12 Pennichuck Water Works Watershed Management Plan 6.0 Existing Protection Measures systems are located so as to avoid square feet and without plumbing groundwater and environmental and electricity; and potable water contamination; streets, roads, etc are supply wells. Many other uses are constructed so that only minimum permitted with a Conservation direct application of road salt is Commission Review, such as bridge required for winter safety and so that crossings and filling or dredging of runoff is channeled to minimize swamps and wet meadows. groundwater contamination; floor drains must be connected to the Floodplain Management District - sanitary sewer system; outside This district is provided to minimize storage of hazardous material shall losses due to flood conditions. All not be directly exposed to the proposed developments in this elements and shall be approved by district require a special permit. the fire and building departments. An Sanitary sewer systems must be environmental impact statement may designed to minimize or eliminate be required and a fire department infiltration of flood waters into the approved, hazardous material systems and discharges from the contingency plan dealing with the system into floodwaters. On-site storage and handling of toxic waste disposal systems will be materials must also be developed. located to avoid impairment to them or Wetlands Conservation District - The contamination from them purpose of this district is to protect during periods of Milford requires an erosion the wetlands and their buffer zones; flooding. Prior to the and sedimentation control to reduce sedimentation of wetlands relocation or alteration of and bodies of water; to aid in control a watercourse the plan for all subdivisions. of non-point pollution; to provide a applicant must notify the vegetative cover for the filtration of Wetlands Board of the NH DES and runoff; to protect fish and wildlife; the flood carrying capacity of the and to control the development of altered course must remain equal to land, structures and land uses that the existing course. No new contribute to the pollution of surface construction, substantial and groundwater. No construction is improvements or fill is allowed on allowed within 25’ of the edge of designated regulatory floodways. wetlands. No construction within 50’ of ponds and watercourses. Prior to development, applications will be considered for technical Permitted uses include: conservation evaluations and standards including areas, nature trails and wildlife danger to life and erosion damage; refuges; parks and recreational areas; importance of services provided to open space; forestry and tree the community by the development; farming; agriculture; and monitoring necessity of a waterfront location; wells for observation purposes. Uses availability of alternate locations; and permitted in buffer areas only safety of access in times of flood. No include: seasonal docks, buildings variance will be issued if there is an and structures not to exceed 120

Page 6-13 Pennichuck Water Works Watershed Management Plan 6.0 Existing Protection Measures

increase in flood elevation due to the under the Site Plan Review development. regulations. o Open space may be required by Nashua the board in developments within Nashua is also divided into many the residentially zoned districts. districts, districts including Rural o Septic systems: individual lots Residence, A Suburban Residence, B must be 40,000 sq.ft. and at least Suburban Residence, C Suburban 500' from an existing gravity Residence, A Urban Residence, B flow public sewer. Engineering Urban Residence, C Urban data on soils, slopes and depth to Residence, Local Business, General bedrock, and perc rates are Business, Central Business, Highway required by the board of health to Business, Park ensure that potential pollution Industria l, General effects will not negatively effect Industrial, Airport the public health. Nashua can require Industrial, Historic o The board of health must studies to determine the Overlay, Planned approve any subdivision plans with regard to drainage, water effect the proposed Residential Development supply and sewage prior to subdivision may have on Overlay, and development. the surrounding Mixed Use o Excavation requires a special Overlay. permit in residential and environment. industrial areas and is prohibited Districts included elsewhere. in the Pennichuck Watershed are Planned Residential Zoning Bylaws / Protection Development, General Business, Districts General Industrial, Airport Industrial, A Suburban Residential, B Suburban Floodplain Development: Special Residential, and C Urban Residence. exception permits are required for development in these areas. Proper Subdivision Regulations design must be included to prevent o The board may require studies to flood damage to structures and determine the effect the proposed minimize the impact on water level. subdivision may have on the surrounding environment. Wetlands: Protects the wetlands and o An approval letter from the NH habitats within. Many of the Water Supply and Pollution Pennichuck watershed areas are Control is required to ensure that included as critical wetlands in this proper erosion and sedimentation section. A fee of $400 is required to control measures are adequate to request a variance to fill wetlands prevent water pollution. and/or floodplains. Common land o The NH Wetlands Board must requirements have provisions to review and approve of plans protect wetlands and other natural areas.

Page 6-14 Pennichuck Water Works Watershed Management Plan 6.0 Existing Protection Measures

amount of protected land in the Mobile Homes: No disposal of watershed. sewage or other discharge of liquid waste is permitted unless piped The buildout analysis in Section 8 directly to the city sewer line. No dry shows four scenarios, two with or chemical toilet is allowed unless it conservation land maintained as is sewer connected. forested or open land, and two with conservation land allowed to develop Junkyards: Junkyards are only into its zoning designations. There is allowed in industrial areas with a not a significant difference in the special permit. pollutant load from those with conservation and those without. This 6.3 Land Ownership is because only the Pennichuck owned lands were maintained as Owning land for the purpose of conservation conservation of natural resources is land in the important to the protection of a water buildout supply because it prevents analysis, and Owning land for the development that has the potential to the quantity of purpose of conservation of decrease water quality. Section 7 land is small natural resources is contains a buildout scenario to show in comparison the effect complete development of to what can be important to the protection the watershed will have on the built out. A of a water supply because quality of the water. more it prevents development significant Pennichuck Water Works and the difference that has the potential to local conservation commissions both would be decrease water quality. own land within the watershed. The noted if the Society for the Protection of NH amount of Forests owns land in some southern conservation land owned by NH towns, but not within the Pennichuck Water Works or others Pennichuck watershed. were larger. Although there is not a signficant difference in the 6.4 Pennichuck phosphorus loadings from the buildouts with and without Water Works conservation, the existing Pennichuck owned lands should be Pennichuck Water Works owns some conserved to minimize the impacts of land surrounding Supply Pond, urbanization and to provide an Harris Pond, Bowers Pond, and Holts adequate buffer to the chain ponds Pond. Past use of Pennichuck’s land and their tributaries. holdings has been for the purpose of water quality protection. The land However, should Pennichuck have to has been maintained in its natural develop their land, the order in which vegetated state. Figure 6-2 shows the they should sell, by subwatershed is:

Page 6-15 Pennichuck Water Works Watershed Management Plan 6.0 Existing Protection Measures

1. Muddy Brook, Hollis 2. Pennichuck Brook to Holt’s The Town of Hollis Conservation Pond; Nashua, south of Rte Commission owns approximately 101A 340 acres within the watershed. All 3. Pennichuck Brook to Pennichuck of these lots are kept as protected Pond forested land. These lands are 4. Pennichuck Brook to Holt’s scattered throughout Hollis as shown Pond; Merrimack on the Land Ownership Map (Figure 5. Pennichuck Brook to Bowers 6-2). Below is a list of these lands. Pond; Nashua, south of Rte 101A o 2.96 acres on Laurel Hill Road 6. Boire Field Brook o 8.47 acres of cave land off 7. Pennichuck Brook to Bowers Witches Spring Road Pond; Merrimack o 3.18 acres off Mooar Hill Road 8. Pennichuck Brook o 5.12 acres off Witches Brook to Supply Pond Area

There is a significant level o 2.43 acres off Sanderson Witches Note, however, that Brook of protection provided by there is an expected o 13.6 acres off Witches Spring both the Pennichuck negative impact on Road water quality from owned lands and the o 3.49 acres off Alsun Drive this development of o 32 acres, Pennichuck Land town-owned lands that are currently preserved o 7.6 acres owned by Jerry Collier, located near the ponds. lands. unbuildable lot, bog land o 29 acres off Oakwood Drive 6.5 Town o 14.9 acres of Town forest off Silver Lake Road Ownership o 2.23 acres of open land off Arbor The conservation commissions in Lane each town were contacted to o 4.0 acres off Mooar Road determine if any additional land was o 1.0 acre off Mooar Road owned within the watershed. As can o 1.16 acres off Pennichuck Drive be seen in Figure 6-2, a significant o 1.93 acres off Forrence Drive amount of land is owned adjacent to o 1.3 acres off Farley Road the chain ponds and their tributaries. o 4.23 acres off Forest View Drive Town owned protected land provides o 2.43 acres off Federal Hill Road additional protection to the o 3.64 acres off Silver Lake Road watershed. o 114 acres; Spalding Park Town Forest off Farley Road Amherst o 8.5 acres of Pennichuck land off Farley Road The Town of Amherst Conservation o 10 acres off Hardy Lane - Commission does own some land, Windmill Lot however, it does not own any land o 29.2 acres; Sterns lot / Parker within the Pennichuck Watershed. Pond Brook

Page 6-16 Pennichuck Water Works Watershed Management Plan

6.0 Existing Protection Measures o 1.06 acres off Farley Road o Private owners, 31,366 acres o 8.63 acres surrounding Forest (27%) View Drive o The City of Nashua, 19,655 acres o 4.5 acres between Forest View (17%) and Federal Hill Drive o Nashua Park Commission, 3,779 o 11.7 acres North of Baxter Road acres (3.2%) o 7.5 acres off Nartoff Road o Audubon Society of NH, 3,398 These lands provide significant acres (2.9%) protection. o Nashua Assembly of God Church, 2,038 acres (1.4%) Merrimack o The State of NH, 179 acres (less The Town of Merrimack owns many than 1%) lots within the watershed. Two of o The Nashua Airport Authority, these lots are protected lands. Both of 161 acres (less than 1%) these parcels are off Naticook Road. Locations of these can be found on There is a significant level the Land Ownership Map. of protection provided by both the Pennichuck owned To minimize the pollutant o 4.2 acres located at 2 Joey Road lands and the town-owned loads, Pennichuck and the is currently being used as open lands. Keeping these lands space. undeveloped will minimize towns must conserve the o 0.45 acres on the corner of the impacts of future existing lands. Naticook Lane and Lorraine development significantly Road, is currently undeveloped as shown in Section 7.0. It land behind the fire station. is in the best interest of the water supply to keep these lands Milford undeveloped. The purchase of additional lands will also increase the The Town of Milford does not own level of protection. any land within Pennichuck Watershed. 6.6 Other Protective Nashua Measures The City of Nashua currently has an Open Space Plan. Within the In addition to the many protective Pennichuck Watershed measures already occurring on a approximately 114,600 acres of land local and state level, watershed are owned as Open Space. Location regulations exist for many water of these areas can be seen on the suppliers around the state. These are Land Ownership Map. A general currently in the process of being breakdown of these areas and who updated. Current regulations for they are owned by is as follows: Pennichuck’s water supply were written in 1934. There are many o Homeowners Associations, issues that need to be addressed in 53,846 acres (47%) the updated regulations such as:

Page 6-17 Pennichuck Water Works Watershed Management Plan 6.0 Existing Protection Measures o Is a 250 foot buffer sufficient? o Should there be a regulation on o Increasing the 75 foot buffer to the amount of phosphorus 250 feet in all sections. loading due to development? o Prohibiting the dumping of o Should policies on recreational hazardous waste and chemical uses of watershed land be waste. more/less strict? o Prohibiting the application of o Is a rule regarding the dumping fertilizers within 250 feet. or discharging of waste into o Monitoring the application of tributary storm drains necessary? pesticides. o Prohibiting people from boating Currently, the New Hampshire or other recreational activities on Department of Environmental Pennichuck Brook below Holt watershed regulations (Env-WS dam, and disallowing boats or 386.50) that deal with the protection other recreational devices using of Pennichuck Pond, Pennichuck motors powered by petroleum or Brook Watershed, and Witches other chemicals on Pennichuck Spring Brook Watershed consist of 7 Pond, Pennichuck Brook above regulations: Holt dam, or on Witches Spring Brook or its tributaries. 1. No buildings where animals are o Prohibit the use of aircraft on kept can be built within 75 feet waters or ice. of these waters. 2. No wastewater, wash water, or Should these amendments be added sewage can be dumped into these to Pennichuck’s Watershed bodies of water or within 75 feet Regulations, they will provide of these bodies of water. additional protection to the supplies. 3. No dead animals or food Further recommendations are scrapings can be thrown within discussed in Section 8. 75 feet of these waters. 4. None of the above buildings or waste can be built beyond 75 feet

of these waters if it is detrimental to said waters. 5. No sawdust or other waste from cutting timber can be thrown or allowed to fall into these waters. 6. No matter, waste, or materials mentioned above may be allowed to remain upon the ice of these waters. 7. No person shall bathe or swim in said ponds or brook.

Proposed updates of these regulations include:

Page 6-18 Pennichuck Water Works Watershed Management Plan 7.0 Buffer Zones Section Contents

7.1 What is a Buffer ...... 7-1 As discussed in Section 5.0 nutrients, boundaries be clearly shown on 7.2 Buffer Zones (Stages) .... 7-2 sediments and other pathogens clearing/grading and sediment control 7.3 Buffer Widths...... 7-2 contribute to general water quality plans. 7.4 Ideal Buffers...... 7-3 degradation over time. In the suburban buffers, contractors There are several BMPs that may be often encroached or disturbed the implemented to minimize the buffer during construction and since degradation impacts of these the buffers were rarely placed on local contaminants. Among the available maps, no management or inspection BMPs is the use of buffer zones. ever occurred. Few were maintained. Buffer zones are a critical component The boundaries often became of any watershed protection program invisible to the property owner with because of their implementability at the result that buffers often became any location, whereas several of the part of the residential or commercial other available BMPs require specific landscaping or lawn. Many were then site criteria in order to be used. used for non-beneficial activities unrelated to the original purpose of This section focuses on the use of the buffer. buffer zones to reduce degradation impacts of water bodies. In many cases, buffer disturbances included tree removal, trampling and 7.1 What is a Buffer? foot trails, filling, encroachment, dumping of yard wastes, erosion by A buffer is a strip of land, stormwater runoff and conversion surrounding a surface water body into lawns. Only five percent of the including tributaries, ponds, lakes and buffer zones established in 36 reservoirs. A buffer typically consists communities were maintained (Kirk, of land left in its natural state to F.S., 1991). provide protection from non-point source pollution including sediments, The above referenced study nutrients, heavy metals, toxics, emphasizes that to achieve the best pesticides, pathogens, salt and results with a buffer zone, they need thermal pollution by providing a filter to be controlled and maintained. for these contaminants. They also provide a pervious area for recharge In spite of these problems, buffer in otherwise impervious watersheds zones can be a good way to provide and help with bank stabilization and initial protection for the chain ponds, to protect riverfront habitat and the their tributaries and wetlands. The river ecosystem. vegetation in the buffer zones can provide protection from nutrients due It is important to note, though, that to plant uptake. Additionally, in buffer zones by themselves have had agricultural areas, these buffer zones mixed success where used. In most can help prevent agricultural uses cases, the buffer zone requirements directly adjacent to streams and were not defined, and the buffer was wetlands by keeping animals away much less effective in practice than from the water (if fenced) in turn planned. For example, in a survey of decreasing the amount of pathogens 36 communities around the U.S. that are able to come in contact with (Heraty, 1993) only half of the water. The removal of contaminants communities required that buffer Page 7-1 Pennichuck Water Works Watershed Management Plan 7.0 Buffer Zones

is dependent on how the buffer is 3. An outer zone, sometimes setup, its vegetation, soils and slope. considered the buffer’s buffer, extends from the forested area to Buffers are also helpful in alleviating the nearest permanent structure or pollution by providing an area for land use. In most cases this is a infiltration. Infiltration of drainage grassed or turf area, that acts as a water through soil filters nutrients, level spreader to change pathogens and sediments. concentrated flow into sheet flow and to help settle sediment and 7.2 Buffer Zones attached pollutants. This zone is particularly important to achieve (Stages) optimal removal of pollutants through a buffer zone. Effective buffers are usually divided into three zones; the streamside zone, the middle zone, and the outer zone. 7.3 Buffer Widths Each performs a different function, An extensive literature search found no consensus on the widths necessary to protect surface waters. Most studies have been site-specific and designed for a particular problem (sedimentation, nutrient removal). Widths used by various agencies and municipalities or recommended by various studies are compiled in Table 7-1. Buffer widths relative to nutrient and sediment removal range from 50 Figure 7-1. Three Zone Buffer, Schueler, 1994. feet to 500 feet, depending on the

sensitivity of the water resource and and has a different width and the land use associated with it. management scheme (Schueler,

1994). There are many factors affecting the

width of buffer strips. Silty loams and 1. The zone directly adjacent to the highly organic soils are highly erosive stream is called the streamside and may need larger buffer strips to zone. Its purpose is to protect the provide adequate protection. Soils physical and ecological integrity such as sand and gravel allow of the stream ecosystem by pollutants to percolate easily and providing shade and leaf cover. quickly, reducing the amount of The most effective streamside pollutants that enter the streams in zones are those with mature, stormwater, but potentially affecting native trees. groundwater baseflow in streams. 2. A middle zone is a width of

managed forest for control of Another factor of concern is slope. pollutants in subsurface flow and The greater the slope the faster the surface runoff through biological water flows over the surface. Faster and chemical transformations, flow decreases the time for infiltration storage in woody vegetation, and causes more erosion. Studies infiltration, and sediment show that slopes of 10% or less deposition. (Channing Kimball, 1993) work best Page 7-2 Pennichuck Water Works Watershed Management Plan 7.0 Buffer Zones to minimize non-point source channelize, since this would reduce or pollution. Other studies suggest that eliminate its effectiveness. Protective 1-2 feet of width should be added for measures are described below. every 1% increase in slope (Channing Kimball, 1993). Still others suggest 7.4 Buffer Criteria that for steep slopes (5-25%), four additional feet of buffer width should As described previously, buffer zones be provided for every extra percent of have been used around the country for slope over 5% (Schueler, 1995). The many years, but with mixed success. most effective buffers are flat. Use of In many cases, the buffer zones have topographic maps and site visits can suffered encroachment that rendered confirm the slope of the land. them ineffective. Consequently, a good buffer zone would have more The best buffer width is thus than just an adequate width for dependent on a number of site treatment of runoff. Some of the specific factors. A summary of characteristics of properly functioning various filter strip studies is shown on buffer zones are described below: Table 7-2. Summaries of the types of models that have been used to predict 1. Dense Vegetation. The or calculate buffer strip widths are vegetative cover of the buffer shown on Table 7-3. None of these zone is probably the most critical are probably appropriate to the aspect of its proper operation and Pennichuck watersheds and are effective removal of pollutants, presented as reference because they whether they are nutrients, are either focused on pollutants such pathogens or pesticides. Dense as pesticides and/or were conducted forested buffers that have in other areas of the country that are remained undisturbed for at least significantly different in topography, the last ten years are generally soils and vegetative characteristics. recognized as the best vegetative cover. This is in part because Although it is difficult to identify a forested areas provide streamside single “best” buffer width, a general shade, wildlife habitat, a dense guideline for sensitive water supply root system for bank stabilization watersheds is a minimum of 400 feet, and nutrient uptake in addition to with a minimum of 200 feet from the pollutant removal capabilities tributaries or wetlands that are of other types of vegetative directly connected to the water body. buffers. These widths are used in Massachusetts for all water supplies Effective Buffer Zones (See Cohen Bill, Appendix I). 1. Dense Vegetation 2. Flow is not channeled In areas of steep slopes, the buffer 3. Infiltration is high may need to be larger while there may 4. Protection from encroachment also be cases where it could be 5. Annual Inspections smaller, for example, where the developer can infiltrate most runoff The understory is also important, and the site is flat. highlighting the importance of not mowing beneath the trees. A In any buffer, it is critical that runoff natural understory is typically not bypass, short-circuit or Page 7-3 Pennichuck Water Works Watershed Management Plan 7.0 Buffer Zones

considered most desirable, but soil can provide a buffer zone, plantings could also be effective. those soils with a high clay content or those that are mostly A mixture of shrubs, trees and gravel may require increased other smaller vegetation could buffer widths for effective also provide an effective buffer. performance at pollutant In many areas, grassed buffers removals. The best infiltration have been used, with either and pollutant removal is found in infrequent or no mowing. A soils with a high organic content grassed buffer would provide and a layer of forest duff on the some pollutant removal capacity surface. Forest duff has been and bank stabilization, however found to be one of the most little shading would occur and the significant factors in the infiltration rates are effectiveness of forest buffers at The best infiltration and not reported to be as pollutant removal. This suggests high as for forested that more mature forests provide pollutant removal is found in buffers. better pollutant removal soils with high organic capacities than do more recently content and a layer of forest 2. Flow is not disturbed forests. channelized. duff on the surface. The second most The organic component of the important soil is also important for two characteristic of a good buffer reasons. First, natural organic zone is that flow is not soil components such as leaf and channelized within the buffer other decomposed materials zone. If flow does channelize, provide sites for absorption and then the buffer zone is effectively adsorption of many pollutants. short-circuited, with little Second, a healthy soil with lots of effectiveness at pollutant wild microorganism activity removal. Water should enter the provides many microorganisms buffer zone as sheet flow, and that will prey on pathogenic level spreaders may be required in organisms introduced by runoff. some areas. If there is the This may reduce the longevity of potential for sheet flow to begin some of the pathogenic organisms to channelize further into the that the buffer is designed to buffer zone, check dams with remove. level spreaders can be used to correct the problem. Maintaining This type of soil also provides a sheet flow becomes more good base for a healthy and dense problematic as buffer zone slopes vegetative cover, one that will increase. In steeper slopes, it is take up many of the nutrients likely that other infiltration introduced by runoff. More measures will need to be added to gravelly and sandy soils can also the buffer zone for it to be provide a buffer zone, however, effective. These must be the width should be increased to developed on a site-specific basis. account for the lower pollutant removal capabilities in spite of 3. Infiltration is high. Buffer zone high infiltration capacity. In clay soils are also critical to the soils, the buffer zone width must equation. Although nearly any also be increased and in some Page 7-4 Pennichuck Water Works Watershed Management Plan 7.0 Buffer Zones

cases these areas may not be stream, fenced bridges should suitable for buffer zones. be provided that prevent the animals from entering the 4. Protection from encroachment. In water and control drainage as a study of buffer zones across the much as possible, providing United States, Heraty, 1993, infiltration for drainage from found that nearly all of the buffer the crossings. zones studied in 36 communities • Signage. Signage should be had suffered from some provided at the buffer zone encroachment. The encroachment fence line to inform nearby ranged from clear cutting to lawn landowners and others of the conversion to dumping and bike buffer zone’s status and trails. In many cases, the restrictions. Any passive encroachment encouraged recreational trails should also channelized flows and rendered be signed to indicate their the buffers useless. Based on a appropriate usage. Signage review of this and other literature, should also include telephone the most important factors in numbers so that people may preventing encroachment call in the case of included: encroachment or questions. • Fencing. Although fencing can be expensive for large • Buffer Mapping. Another buffer zones, it is particularly important aspect of a good important where livestock are buffer is that it is protected by an issue. The term “good being shown on local and fences make good neighbors” regional maps of the area. is very true for buffer zones. This should include efforts to have local Planning Boards Fencing of buffer zones and Conservation should be used wherever Commissions show the buffer livestock can gain access to zones on their maps. This the buffer zone without it, and should help prevent future across areas where vehicle encroachment from projects access may be problematic. and provide awareness of the If pedestrian access is to be buffer’s existence and allowed for local pathways, importance to other agencies. pathways must be constructed such that they do not create BUFFER ZONE channelized flow. Fencing DO NOT DISTURB should also accommodate the pedestrians while blocking This is a protection zone that access to vehicles. If cattle or buffers the Pennichuck Water other livestock must cross a Works Water Supply from water Factors in Preventing quality threats. It should not be Encroachment mowed, harvested or otherwise 1. Fencing disturbed by human or livestock 2. Signage activity. Please contact 3. Buffer Mapping Pennichuck Water Works at 4. Public Education (882-5191) if you see human or livestock activity in this buffer. Page 7-5 Pennichuck Water Works Watershed Management Plan 7.0 Buffer Zones

• Public Education. Whether importance of maintaining it Pennichuck Water Works as is. owns the buffer zone, or has a conservation easement of 5. Annual Inspections. The final some form, information component of a good buffer is should be provided to the periodic inspections. The adjacent landowners. This encroachment discussed above is information should include particularly problematic, and the restrictions on the buffer should be inspected on an annual zone as well as the basis.

Page 7-6 Pennichuck Water Works Watershed Management Plan Table 7-1. Comparison of Required Setbacks Recommended Buffer Author Article Related Activity Width (feet) Any activity which causes land movement, Town of Scituate, construction, or any type of discharge is MA Code of Bylaws, Zoning prohibited 150 NH Rivers Management and State of NH Protection 483:9 Land application of solid waste is prohibited 250

Pennichuck Water Existing Watershed No fertilizers, compost, or other organic Works Regulations debris allowed within the buffer 250 Town of Amherst, Any activity which would result in the NH Zoning Ordinance deterioration of water quality is prohibited 100 Town of Hollis, NH Zoning Ordinance Septic tanks or leach fields prohibited 150 Commonwealth Pollutants (manure, fertilizers, pesticides and 400 to reservoir, 200 of MA 350 CMR 11.00 herbicides included) are prohibited to tributaries Town of Southborough, MA Zoning By-Laws Sewage disposal is prohibited 500 Buffer recommended for 80% removal of State of RI Coastal Buffer Implementation pollutants 75 Buffer recommended for 90% removal of State of RI Coastal Buffer Implementation pollutants 200

sediment-160; nutrient- Kimball, Joan Land must remain in its natural state within 300; pesticide- 80 to Channing Riverways Community Guide these buffers 300; pathogens-2700 Land must remain in its natural state within Schueler, Thomas Controlling Urban Runoff these buffers 100-300 The Architecture of Urban Land must remain in its natural state within Schueler, Thomas Stream Buffers these buffers minimum 100 NC Cooperative Recommended setback is for fields receiving Extension Senate Bill 1217 swine manure 50

100 (increased if the Protecting Water Supply Fact water supply is NC Farm A Syst Sheet Recommended setback is for animal waste downgradient of waste

NC Cooperative Protecting Water Supply Extension Service Springs Recommended setback is for animals 100 Prevention, Collection and Treatment of Concentrated Filter area required to treat barnyard runoff on Wright, Peter Pollution Sources on Farms a slope of 6% 165-230

Commonwealth MGL c.92S.107A(b) Surface 400 of water body of MA Water Protection Alterations to land or buildings 200 of tributary

Note: Not all municipalities in Massachusetts and New Hampshire were reviewed.

Pennichuck Water Works Watershed Management Plan Table 7-2. Summary of Various Filter Strip Studies Region / Vegetated Type of Soil Reference State Study Area Vegetation Type Slope Results Up to 96% reduction in nitrate, 88% reduction in Land area treated by swine fescue grass seeded phosphorus and 80% reduction in sediment, 0% Chaubey, 1994 Arkansas manure 1.5 m x 24 m at 500 kg/ha silt loam 3% reduction in bacteria.

Poultry litter tested for fecal planted tall fescue Maury silt Coyne, 1995 Kentucky coliform 4.6m x 9m and bluegrass loam 9% Area not sufficient for bacterial removal. 1.5 m was the minimum width required for nitrate Dairy manure applied at 90 removal, 4.0 meters was the minimum required for mT/ha with buffer strips up sufficient ammonia, sulfate, and potassium to 4 m wide on the Chester silt removal. Fecal was only reduced by up to 18% in Doyle, 1977 Maryland downslope edge 7m x 4.9 m tall fescue loam 10% these studies.

A paved feedlot with two consecutive strips and settling basin 1/6 the size of Edwards, 1983 Ohio the feedlot 4.5 x 30 m fescue grass ~ 2% Total system removed 81-89% of pollutants.

red fescue, tall fescue, bluegrass, Massena Schellinger, 1992Vermont Bacterial reduction 7.6 x 22.9 m ryegrass silt loam 2% Fecal was reduced by approximately 30%.

native grasses mostly bromegrass, Canisteo For herbicide reduction and bluegrass, and silty clay Retention ranged from 8-100% for herbicides and Arora, 1995 Iowa sediment reduction 1.5 x 20.12 m fescue loam 3% 40-100% for sediment.

Cropland runoff treated with swine manure applied at a rate of 45,000 l/ha/yr, filter strip elongated bowl Study demonstrated that filter strips are effective in Aull, 1980 Michigan shape 0.2 ha not identified sandy loam 1.80% more than just strips. Iowa State Agroforestry Research Team, native trees and Cost was rougly $65/ha and reduced all levels of 1994 Iowa Pasture lands and cornfields 7.5 m wide strip switchgrass ~ ~ pollutants below those in the control area.

Application of liquid N at Effectiveness was highly dependent on the 112 kgN/ha and application condition of the filter itself with the most removal of poultry litter at 8.9 m- occurring at the interface of the source area and the Magette, 1986 Maryland T/ha 5.5m x 22m fescue grass sandy loam 3-5% filter. Efficiency of strips decreased over time.

A 9.2 m strip was more effective than a 4.6 m strip. Magette, 1989 Maryland Repeated study above 5.5m x 22m fescue grass sandy loam 3-5% Reductions were less than 50% for nutrients.

31m x 36.6m; 18.2 m acted as bromegrass, alfalfa, Fayette silt Sediment retention of 70% within the first 3m, Robinson, 1996 Iowa Sediment reduction filter strip orchardgrass loam 7%, 12% reduction past 9m very small. Researchers concluded that standardizing site requirements and careful monitoring of installation 33 farms in VA were 94% dominated by and use would increase the successful application Dillaha, 1986 Virginia studied varied fescue grass varied varied of filter strips.

Pennichuck Water Works Watershed Management Plan Table 7-2. Summary of Various Filter Strip Studies Region / Vegetated Type of Soil Reference State Study Area Vegetation Type Slope Results

Micro-targeting reduced sediment by 31% at $80 per ton; filter strips reduced sediment by 26% at A comparison of the $91 per ton, however, adding administrative and physical and economic implementation costs led filter strips to be more impacts of filter strips and cost effective. Farmers are also more willing to give microtargeting (setting up land at the edge of a field than the middle, as is Pritchard, 1993 Indiana aside highly erodible land) ~ native trees silt loam 0-6% sometimes required in the micro-targeting program.

Determine the effect of reed canary grass, lengths of filter strips in redtop, and tall Cecil clay Background runoff concentrations can be achieved Bingham, 1980 North Carolina improving water quality 12m x 13m fescue loam 6-8% with a buffer area to waste area ratio of 1:1. Concentrations of nitrate and sediment did not Poultry litter applied at a Captina silt decrease significantly past 3.1m, for TKN 9.2m, Chaubey, 1993 Arkansas rate of 5 kg/ha 1.5m x 24.4m fescue grass loam 3% and for phosphorus 6.7m.

Determine if filter strips were a feasible alternative treatment technique for reed canary grass, feedlots. Runoff from a bromegrass, Filter strips reduced sediment, nutrients, and Dickey, 1981 Illinois settling basin 12m x 91m orchardgrass ~ 0.50% oxygen demanding materials from runoff by 80%.

filter strip Determine effectiveness of lengths of 0, 4.6, Groseclose Dillaha, 1985 Virginia filters in feedlots and 9.1 m orchardgrass silt loam 5% 9.1 m plots were more effective than 4.6m plots.

Determine the pollution fescue with 114 l/cow/day of wastewater was produced, an area potential from a milkhouse 9.1m x 27.4m invading annuaals of 82 square meters of filter strip was required for and feedlot operation and and 9.1m x of crabgrass and Hosmer silt each cow. A downslope length of 19.2m was Paterson, 1977 Illinois evaluate filter strip system 36.6m barnyard grass loam ~ required to effectively retain pollutants.

Effect of filter strip on red fescue, tall Massena Reduction in sediment concentrations were 45%, Schwer, 1989 Vermont commercial dairy 10.6m x 26m fescue, and rygrass silt loam 2% phosphorus 78%, TKN 76%, and ammonia 2%.

Buffering capacity of corn plots and native plots were effective when used together. Corn reduced Determine the ability of nutrients up to 98%, orchardgrass up to 77% and land and cropping practices corn, orchardgrass sorgham/sudangrass up to 82%. A 36m filter strip as filter strips to absorb and Barnes was recommended for all vegetative types for this Young, 1980 Minnesota pollutants from feedlots 4.1m x 27.4m sorghum/sudangrass loam soil 4% 310 head feedlot.

Cecil Overall reduction were: TSS (30-60%); TKN (35- Determine removal sandy loam 60%); ammonia (20-50%); nitrate (50-90%); efficiencies of grass filters; 6m, 13m, and to clay phosphorus (60%) and phosphate (50%). Most Daniels, 1996 North Carolina runoff from corn field 18m wide strips fescue grass loam 2-5% removal occurred within 7 m. The 4.3m strip had 75% reduction, while the 8.5m Compare effectiveness of 4m x 37m x (4.3 sandy clay strip had 85% reduction. It was also concluded that field edge grass filter strips and 8.5m in fescue, weed, and soil/ sandy 4-6% / long term effectiveness is subject to precipitation Parsons, 1990 North Carolina and riparian zones length) crabgrass loam 1% patterns. native grasses including 1.5m x 4.6m bromegrass, Canisteo Effectiveness of filter strips and 1.5m x bluegrass, and silty clay On no tillage plots, reduction averaged 35-60%, Mickelson, 1993 Iowa on herbicides 9.1m fescue) loam 3-6% conventional tillage had 28-72% reduction.

Pennichuck Water Works Watershed Management Plan Table 7-3. Buffer Zone Calculation Methods Model Abbreviation Components Application

Chemicals, Runoff, and Erosion from Agricultural Hydrology, erosion, nutrient Outdated, GLEAMS is a more advanced version Management Systems CREAMS and management of CREAMS.

Groundwater Loading Effects To determine nutrient and pesticide levels on of Agricultural Management Hydrology, erosion, nutrient various farms and the amount of each leaving the Systems GLEAMS and management farm. Weather, hydrology, erosion, nutrient cycling, pesticide fate, soil temperature, tillage, crop To determine the impacts that soil erosion on Erosion/Productivity Impact growth, management and croplands has on water quality, and the adequacy Calculator EPIC economics of different management practices. Climate, infiltration, runoff, soil erosion, soil moisture and Water Erosion Prediction temperature, crop growth, plant Determination of the effectiveness of buffer and Project WEPP residue and tillage filter strips and other agricultural BMPs.

Rainfall, runoff, soil erodibility, (Revised) Universal Soil slope length, steepness, and Designed to estimate erosional load from Loss Equation USLE / RUSLE cover management hilltops.

Climate, infiltration, runoff, soil erosion, soil moisture and To determine hydrologic, sedimentation, and Simulator for Water temperature, crop growth, plant nutrient and pesticide transport in large Resources in Rural Basins SWRRB residue and tillage watersheds.

Simulation of Production and Sediment yield, plant growth, Rangeland management (will be of little use to Utilization of Rangelands SPUR animal and economics MDC).

Areal Nonpoint Source Watershed Environment Erosion and sediment control and water quality Response Simulation ANSWERS Weather, flow erosion analysis associated with erosion.

Topography, hydrology, Agricultural Nonpoint Source erosion and sediment transport, Analysis of nonpoint source pollution from Pollution Model AGNPS chemical transport agriculture.

Sedimentology by Design of sediment control structures on surface Distributed Model Treatment SEDIMOT II Hydrology, sedimentation mined land (will be of no use to MDC).

On-farm management, Nitrate Leaching and soil,climate, aquifer data, Used for groundwater quality (will be of little Economic Analysis Package NLEAP economic informatin use to MDC).

Support Technology of Environmental, Water and Agricultural Resource The selection, evaluation, siting, and design of Decisions STEWART Hydrology, pollutant loads nonpoint source control systems.

Pennichuck Water Works Watershed Management Plan Section 8.0 Buildout Analysis Section Contents 8.1 Buildout Analysis ------8-1 A detailed analysis of the phosphorus Works, a buildout analysis with levels in each subwatershed and in the Pennichuck Water Works chain ponds during buildout conservation lands was developed and conditions was conducted to modeled to compare the zoning determine the potential water quality scenarios. The comparison was used impacts from future land uses in the to determine the impacts on the water watershed. The purpose of doing a supply if Pennichuck were to sell buildout is to identify the increase in these lands and allow total pollutant loadings to the chain ponds urbanization of the watershed. This under future conditions so the was conducted by overlaying the appropriate planning may be done to zoning map with the mapped minimize these impacts as growth privately owned lands (Figure 8-1). occurs in the watershed. The four buildout scenarios are The Nashua Regional Planning outlined below: Commission (NRPC) zoning data (Figure 6-1) was used to determine 1. Scenario 1. Residential the different within the watershed without Conservation - during buildout conditions. This type Buildout based on of buildout analysis does not provide zoning map with a detailed review but represents a residential worst case under existing zoning. development in A buildout analysis Based on these land areas, the same Hollis (assumes identifies the increase in model and methodologies used for the development of pollutant loadings to the nutrient analysis were applied to Pennichuck- obtain phosphorus loadings from each owned lands chain ponds under future subwatershed under future conditions. occurs). conditions. Four buildout scenarios were 2. Scenario 2. identified and analyzed based on Agricultural without zoning and protected lands data. Conservation - Buildout based on zoning map with The zoning map shows the worst case agricultural development in future buildout for the area. However, Hollis (assumes development some areas of the watershed (in the of Pennichuck-owned land Town of Hollis) are zoned as either occurs). residential or agricultural so that 3. Scenario 3. Residential with either of these land uses may be Conservation of Pennichuck developed. Thus, both residential and Lands - Buildout based on agricultural scenarios were developed zoning / conservation map and modeled based on the zoning overlay with residential map, resulting in the first two development in Hollis. scenarios. 4. Scenario 4. Agricultural with Conservation of Pennichuck However, the zoning map does not Lands - Buildout based on account for any privately owned zoning/conservation map conservation lands. Since much of overlay with agricultural this conservation land is under the development in Hollis. ownership of Pennichuck Water

Page8- 1 Pennichuck Water Works Watershed Management Plan Section 8.0 Buildout Analysis

The percent contribution of each scenario is provided on Table 8- phosphorus loadings by subwatershed 2. for each of the four scenarios is shown on Table 8-1. Subwatersheds As shown on Table 8-2, a buildout PBS and MB1 are the greatest scenario using agricultural

Table 8-1. Percent Phosphorus Contribution by Subwatershed for Buildout Conditions Subwatershed Name Scenario 1. Scenario 2. Scenario 3. Scenario 4. and Designation Residential Agricultural Residential Agricultural without without with with Conservation Conservation Conservation Conservation PBS. Pennichuck 19% 16% 19% 16% Brook to Supply Pond PBB. Pennichuck 14% 11% 12% 10% Brook to Bowers Pond PBH. Pennichuck 14% 11% 12% 10% Brook to Holt’s Pond PBP. Pennichuck 8% 7% 8% 7% Brook to Pennichuck Pond WBE. Witches Brook 11% 8% 12% 8% East WBS. Witches Brook 8% 10% 9% 11% South WBN. Witches 4% 4% 5% 4% Brook North SPB. Stump Pond 6% 5% 6% 5% Brook BFB. Boire Field 8% 6% 7% 6% Brook MB1. Muddy Brook 9% 22% 10% 22%

Table 8-2. Total Phosphorus Loadings from Buildout Scenarios Buildout Scenario Total Phosphorus Loadings (lbs/yr) Scenario 1. Residential without Conservation 16,465 Scenario 2. Agricultural without Conservation 19,487 Scenario 3. Residential with Conservation 15,258 Scenario 4. Agricultural with Conservation 18,121 contributors of phosphorus under an development without the conservation agricultural buildout scenario, both lands, represents the worst case with and without the conservation buildout scenario with about 19,500 land. The residential buildout reveals pounds of phosphorus per year being PBS, PBB and PBH to be the largest contributed tot he chain ponds. This is contributors of phosphorus. A about a 180% increase in loadings detailed breakdown of the phosphorus from the existing conditions. laodings by subwatershed and land However, it is not likely that these use for each buildiout scenarios can areas will be developed strictly as be found in Appendix G. A summary agricultural, and it is expected that of the total phosphorus loadings for residential lots will be developed. In

Page8- 2 Pennichuck Water Works Watershed Management Plan

Section 8.0 Buildout Analysis this case, the phosphorus loadings to in-pond goal. Nevertheless, the other the pond increase by about 140%. ponds in the watershed will still have This assumes that all privately owned substantially higher phosphorus levels conservation lands will be urbanized ranging from 0.065 to 0.113 mg/l. in the future. Table 8-3. In-pond Concentrations for Buildout Scenarios If the conservation lands within the Subwatershed Scenario 1. Scenario 2. Scenario 3. Scenario 4. watershed are not sold for future Residential Agricultural Residential Agricultural development, the watershed will see without without with with Conservation Conservation Conservation Conservation an increase in phosphorus loadings of (mg/l) (mg/l) (mg/l) (mg/l) about 120%. Although this is still a Pond significant increase, the impacts are Stump Pond 0.065 0.066 0.065 0.066 lower than if all of the private owned Pennichuck 0.069 0.113 0.067 0.109 conservation lands were developed Pond and the results emphasize the Holts Pond 0.101 0.112 0.096 0.107 importance of maintaining Bowers Pond 0.067 0.072 0.063 0.068 undeveloped lands within the Harris Pond 0.057 0.059 0.054 0.056 Supply Pond 0.054 0.055 0.052 0.053 watershed. This is confirmed below with an analysis or the in-pond From a more realistic point of view, it concentrations under the four buildout is unlikely that a large portion of the scenarios. watershed will be developed as

agricultural land and more likely that As with the nutrient analysis residential land will be developed. presented in Section 4.0, in-pond Under the residential scenarios, the concentrations were calculated for in-pond concentrations are still each buildout scenario for each of the expected to increase significantly chain ponds. Table 8-3 provides a from existing conditions, but the summary of the estimated future in- overall impacts in each of the ponds is pond concentrations for each buildout lower than that seen for agricultural All four scenarios scenario. As expected, the agricultural development. buildout, assuming the private owned show high levels of conservation lands are developed, The above analysis does not show a phosphorus in the results in the highest in-pond significant difference between the concentrations, with a concentration ponds at buildout. buildout scenarios with and without of 0.059 mg/l in Harris Pond. This is conservation lands. This is because Protective more than twice the in-pond goal of the conservation lands in the measures are 0.025 mg/l. Other ponds in the watershed are small in proportion to watershed, such as Holts Pond, may needed. the areas that may be developed. If reach levels of 0.112 mg/l under this larger quantities of conservation land scenario, which is about four and one were owned and maintained, there half times higher than an in-pond goal would be a significant difference of 0.025 mg/l. between the scenarios with and

without conservation lands. Under the conservation scenarios, the Although there isn’t much of an worst case in-pond concentration for increase between these scenarios, it is Harris Pond is expected to decrease important to keep as much from 0.059 mg/l as identified above to undeveloped land within the 0.056 mg/l, which is about twice the watershed to help minimize the

Page8- 3 Pennichuck Water Works Watershed Management Plan Section 8.0 Buildout Analysis impacts of urbanization and to required at developments will help the provide adequate buffers for each of situation. The phosphorus loading the ponds and their tributaries. As calculations are based on “typical” outlined above, impacts could be real-life land uses (forested, suburban, significantly reduced if Pennichuck or commercial, etc.) If the methods of the existing communities were to developing these land uses can be obtain additional private undeveloped improved to reduce the runoff lands in the future. coefficients and overall imperviousness, then future Although each of these future development impacts can be scenarios show a worst-case minimized. These steps, however, development to the fullest, any must be taken at all new increases will decrease water quality. developments and when The analysis suggests that minimizing commercial/industrial sites come up development pressures by rezoning or for approval for substantial increasing the level of infiltration modification.

Page8- 4 Pennichuck Water Works Watershed Management Plan Section 9.0 Recommendations Section Contents 9.1 Findings ------9-1 Based on the water quality evaluation 9.2 Recommended described in earlier sections, ten The most easily measured factor in Actions ------9-7 major problem areas were identified evaluating the extent of the problem in the Pennichuck Watershed as is the measurement of total summarized on Table 9-1. Each of imperviousness or the percentage of these problems is described in more area that is not “green” (Schueler, Fall detail below, followed by 1994). Schueler defines recommended actions to alleviate the imperviousness as the sum of roads, problem or to minimize the problem parking lots, sidewalks, rooftops and in the future. other impermeable surfaces of the urban landscape. There are two 9.1 Findings primary components of imperviousness: 1) rooftops; and 2) transportation system. The rooftop component is somewhat fixed, while Problem 1: Loss of the transportation component is Baseflow/Increased highly varied based on the layout of Runoff/Stream Channel streets and parking. Modifications Table 9-1 As urbanization encroaches in all Top 10 Problems in Pennichuck Watershed parts of the watershed, stormwater 1. Loss of baseflow, increased stormwater runoff and stream runoff is increased. Because the channel erosion result in declining water quality. stormwater picks up many pollutants 2. Future development is likely to increase these problems. as it passes over impervious surfaces, 3. The Pennichuck ponds appear to be filling in rapidly, which a higher proportion of stormwater will further exacerbate water quality and quantity problems. flow in the watershed is not beneficial 4. Transportation facilities in the watershed are widespread and to water quality. At the same time have major impacts on water quality. that stormwater flows increase, 5. Agricultural activities that result in livestock using tributary infiltration and recharge of streams for watering may result in the introduction of groundwater decrease. Although it waterborne pathogens and high nutrient loads. may take a long time to affect 6. Multiple “hot spots” in the watershed pose chemical risks to regional groundwater levels, it is the water supply and may threaten biological activity that likely to be the eventual result. As normally cleanses water quality. groundwater levels decrease, 7. There is a general lack of understanding of watershed groundwater discharge to streams protection principles among the regulatory, planning, public during low flow conditions also works and engineering communities. decreases. This has already been seen 8. There is a general lack of understanding of watershed in the Pennichuck watershed. protection principles among the watershed businesses and residents. 9. Pennichuck Water Works Corporation lacks up to date Baseflow provides a typically very regulatory authority within the water supply. clean source of water to ponds and 10. The available database is lacking. streams, so its loss is detrimental to the health of the watershed. Fish and wildlife, wetlands, and water supply As imperviousness increases, stream resources are all affected by this channels respond to the more severe problem. The decline of water quality and more frequent flooding by and quantity for water supply are increasing their cross-sectional area to particularly important. accommodate the higher flows. A loss

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of stable streamside vegetation may increases in nuisance species and result. This results in channel aquatic vegetation. instability, which tends to trigger a cycle of stream bank erosion and loss Imperviousness also increases annual of stable aquatic habitat. This loss of water level fluctuations in fresh water stability may increase both the rate of wetlands. Studies by Taylor, 1993, filling in of ponds on the system, and showed that the richness of both water quality in terms of turbidity and wetland plant and amphibian the pollutants that are carried with the community dropped sharply as stream increased sediment load. watersheds increased in imperviousness. As stream habitat Table 9-2. Pennichuck Watershed becomes more degraded, both aquatic Imperviousness vegetation and animals are negatively Subwatershed Imperviousness Subwatershed affected. Diversity tends to be Drainage Area reduced, with native species being (in acres) replaced by invasive plants. Most PBS 14% 1,285 aquatic life, other than the nuisance PBB 29% 2,390 invasive aquatic weed species and PBH 15% 1,508 nuisance species of invertebrates such PBP 5% 1,978 as blood worms (pollution-tolerant WBE 23% 1,365 Chironomidae) are the survivors. WBS 5% 3,193 This change is detrimental to both WBN 19% 1,425 recreational users of the watershed SPB 17% 1,516 and to the water supply. BFB 36% 1,006 MB1 6% 2,317 Table 9-2 shows the percent Total Acreage 17,983 imperviousness by subwatershed of Total Imperviousness =2728/17983=0.152=15.2% the Pennichuck watershed. Total watershed imperviousness is The increasing imperviousness can estimated at 15%. Schueler (1994) also increase phosphorus loads, and suggests that the cycle of stream and result in overenrichment of the water quality degradation begins at receiving waters, in this case the approximately 10% imperviousness. Pennichuck ponds. He also suggests that once background loads exceed 20-25%, it Impervious surfaces also increase may be difficult or impossible to fully local air and ground temperatures by restore water quality. as much as 10-12° (Schueler, 1994). This is the result of the impervious Problem 2: Impacts of Future surfaces absorption and reflection of Development on Water heat. Stream temperatures may Quality Expected ultimately be affected with increased stormwater and decreased cool Not only has water quality baseflow discharges. The stream deteriorated over time, but it is likely warming is detrimental to both that it will deteriorate further as future aquatic life and water supplies, development and urbanization of the resulting in the loss of aquatic fish watershed occurs. The buildout and other species as well as potential analysis described in Section 7.0

Page 9- 2 Pennichuck Water Works Watershed Management Plan Section 9.0 Recommendations suggests that nutrient loads will quality of the Pennichuck pond increase significantly. This increase in system. nutrient loading will result in more pronounced taste and odor problems Problem 3: Chain Ponds are during the summer when algal blooms Filling In are common, higher turbidity during Limited sampling conducted for this parts of the year, and increased stream study suggests that the chain ponds channel erosion. Fish kills are likely, are quickly filling in with sediment along with increases in the frequency from the watershed. In some cases, and intensity of storm flows. Base the ponds may already be largely flow may be further decreased, and filled with loose sediment, and eventually may result in the primary washing over sediment during large stream drying up during droughts. storm flows. Should this happen, This could have a serious effect on water quality could deteriorate much aquatic habitat and wetlands in the more rapidly than it has in the past. watershed, further decreasing their This is because the chain ability to filter pollutants during storm pond system has acted as flows. a presedimentation system As turbid, polluted storm for the water supply. As time goes on, if imperviousness flows enter the chain pond increases to the extent that it is As turbid, polluted storm system, they are retained physically possible, Pennichuck will flows enter the system, likely have to rely more on other in the ponds, providing a they are retained in the sources of supply and decrease its use trapping effect for many ponds, providing a of the Pennichuck ponds. Since this is trapping effect for many pollutants. likely to occur at the maximum pollutants. Most of the demand time of dry summertime, it significant pollutants, could eventually result in difficulties including phosphorus and many in meeting maximum day demands bacteria, are “particulate” or tend to for the system. If adequate water is be associated with particles of soil. available for use, it may require Thus they are transported most additional treatment. Chemical use effectively with soil particles. These for settling and filtration expenses are same particles tend to settle out in also likely to increase as water quality slow areas and in ponds, and if the deteriorates. ponds are deep enough, the sediments

are retained. Since EPA is expected to increase the requirements for systems with poor In natural systems, sediments slowly quality sources, Pennichuck may be build up over millions of years until subject to these additional treatment ponds eventually become wetlands requirements as water quality and finally land. In a natural system deteriorates. EPA is likely to require without urban development, this that this additional treatment is at the could take millions of years. In the front of the treatment train, for Pennichuck watershed, this same example, pre-sedimentation facilities. filling in process could occur in a This provides very strong economic matter of decades or even years as incentive to improve the raw water urbanization and its resultant

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imperviousness increases automotive leakage and repairs, and uncontrolled. other pollutants from exhaust. The result of all this is that roadways are Even if the sediments are not spilling loaded with pollutants which wash over, they may be exerting a water into nearby watercourses during every quality impact through their oxygen rainstorm. demand. As ponds develop a large sediment layer, the decomposition of Although some advances have been this material typically creates an made in controlling this pollutant load oxygen demand. As the sediments in newer roads, controls on major decompose and degrade, oxygen is roadways are typically inadequate pulled out of the water, often creating even now, and particularly on older an oxygen deficient layer at the roadways where the typical goal was bottom of ponds and lakes. As to get the water to the nearest stream oxygen is lost from this lower layer, as quickly as possible through piping. chemical changes begin to occur that This rapid transport increases result in the release of some of the pollutant loads and exacerbates the trapped pollutants from the sediments problem of imperviousness and back into the water increased stormwater runoff. column. This can Additionally, roadways, airports, and Roadway drainage may occur to the extent parking lots provide mostly that some ponds uncontained areas for spills of result in the direct transport actually produce a hazardous materials and other of hazardous pollutants to phosphorus load undesirable fluids. These may result the water supply. internally, from accidents, since the typical hastening the response to these accidents is to wash eutrophication spills off the road and into the nearest process exponentially. This can result waterway. Because roadway drainage in water quality that is actually worse is typically uncontrolled in the than the level of watershed watershed, this may result in the development would suggest. direct transport of hazardous pollutants to the water supply. Problem 4: Transportation Impacts Aquatic habitat in the watershed is also likely to be damaged, with kills Because the Pennichuck watershed of many of the organisms that has developed at a rapid pace and normally act to remove pollutants because it contains many large and from the water column. Since a small roadways, transportation diversity of organisms helps to impacts are particularly problematic. control water quality impacts by Cars, so critical to life in Southern decomposition, the loss of these New Hampshire, are a major source organisms is a detriment to both water of a number of types of watershed supply and recreational uses of the pollutants. This includes copper from watershed such as fishing and brake pad wear, zinc from wear and aesthetic enjoyment. tear of automobile tires, atmospheric deposition of lead from the exhaust of diesel-fueled vehicles, solvents, oils and other automotive fluids from

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Problem 5: Agricultural Problem 6: Hot Spots Impacts As described in Section 6.0, on In some limited parts of the upper pollution sources, the watershed watershed, particularly in Hollis, contains a number of point sources or there remain large tracts of hot spots. These include known agricultural lands. These lands hazardous waste sites, permitted generally provide a benefit to water hazardous waste generators where quality in the watershed by retaining spills of significant hazardous pervious surfaces. However, where chemicals could occur, and smaller cattle and horses are pastured with potential sources of pollutants such as use of tributary streams for their car dealerships, gas stations, and auto drinking water source, they may repair shops. From these locations, a present a hazard related to pathogenic variety of hazardous chemicals, oils, organisms. A number of pathogenic and nutrient loads from car washing organisms are produced by humans activities may emanate. These areas and animals, and if feces enter may be a significant source of streams untreated, the pathogens must pollution if not adequately controlled be removed before the water can be with Best Management Practices. distributed. Unfortunately, some of There are dozens of each of these the most recently discovered locations within the watershed, organisms, particularly particularly the most urbanized Cryptosporidium, have escaped portion of the watershed along Route conventional treatment systems and 101A. disinfection to cause waterborne disease outbreaks. Since this Problem 7: Lack of particular organism is often Community Understanding associated with cattle, particularly The problems identified above are calves, there is the potential for well known to watershed engineers significant water quality impacts. and scientists, however, they are not typically This organism, which sickened recognized as 400,000 people in Milwaukee and issues by most killed 100, is commonly found in regulatory, Many fishermen lament the loss large numbers in poor quality sources planning, public of favorite trout streams – now of water. It is highly resistant to works staff or gone because trout can not disinfection, and has escaped the engineering conventional treatment systems when community in tolerate the higher stream they have become overloaded due to general. This is temperatures and pollutant the large number of organisms and largely because operational practice such as recycled many of the loads. backwash. Even with every concepts are precaution taken at the treatment end, relatively new it is still critical to limit the number of (within the last ten years) but are these organisms entering raw water increasingly being applied around the sources. United States. In general there has been resistance to change among the engineering community, largely

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because standardization of the waterborne disease outbreaks such as methods has not yet been done. This the one that occurred in Milwaukee. has also resulted in a reluctance by some planning boards and regulatory Still, most people in the watershed are authorities to address these problems, probably not aware of the fact that in part because many of the solutions their everyday actions and their own are relatively new. In many cases, property have a significant impact on regulatory, planning, and engineering water quality. Similarly, they are communities are just not aware of the probably also unaware of the things issues yet. that they can do as individuals to reduce the impacts. Problem 8: Lack of Understanding Among This information is also not taught in General Public the schools. For the most part, teachers are unaware of the problems, Many federal and state “watershed and this subject is not included in initiatives” developed so far by EPA most curriculums. Science teachers and DES have focused on the larger may touch on the subject, but a watersheds of rivers such as the focused program as related to the Merrimack. While these initiatives are Pennichuck watershed is not known beginning to get the word out, most to be taught. residents in watershed Problem 9: Lack of Most people in the towns and in Regulatory Control/Authority watershed are probably general are probably not Pennichuck Water Works Corporation not aware of the fact that familiar with does not have any authority within the their everyday actions can many of the watershed. There is certainly influence based on the fact that many have a significant impact concepts discussed in of the Towns are supplied water by on the environment and this report. Pennichuck, but in some cases there is water quality. However, it is little incentive for Towns to cooperate likely that they other than the fact that neighbors are familiar helping neighbors is the right thing to with the degradation of the water do. Watershed regulations do exist, resources around them. For example, authorized by the State Legislature in many fishermen often lament the loss 1934. However, these regulations are of their favorite trout fishing streams. outdated and do not provide the kind This is usually due to the fact that of controls that would assist trout can not survive in the higher Pennichuck Water Works Corporation temperatures that result from in reducing water quality impacts increased stormwater flows off heated within the watershed. Without more impervious areas and the loss of specific regulations, Pennichuck must shaded stream channels that results rely on the goodwill of watershed from eroded stream banks. Many communities in protecting its water people have also become aware of supply. While most communities have drinking water quality problems been generally cooperative in the based on press accounts of past, it is unknown how they will

Page 9- 6 Pennichuck Water Works Watershed Management Plan Section 9.0 Recommendations react when asked to address the Table 9-3 Methods to Reduce Future Imperviousness of impacts from their communities. the Pennichuck Watershed Require that post- Subdivisions and commercial/industrial developments should Problem 10: Water Quality development runoff be required to match post-development conditions to pre- Database is Insufficient equals development conditions for runoff up to the ten-year storm. predevelopment All water from a two-year storm should be infiltrated. Peaks While limited sampling was done for runoff should be attenuated and stored for slow release in larger than this study, and previous analysis ten-year storms (up to 100-year). information was incorporated into the Minimization of • Use angled parking and smaller spaces on one-way streets report where possible, a solid Parking Lot Impacts and parking lots • Reduce parking ratios required where possible database of raw water quality • Use vertical parking structures in urban areas where information within the watershed possible does not exist. This is not uncommon, • Use permeable spillover parking where appropriate since most water systems have relied • Modify landscaping of parking lots to use permeable on finished water quality and many dividers and street side buffer strips (See Figure 9-1) water systems still rarely collect Reduce • Encourage cluster development wherever possible Transportation watershed information or data. • Use skinny streets to reduce roadway impacts Impacts of • Use grass swales instead of curbs and gutters However, this results in a lack of Subdivisions • Use one-sided sidewalks or paths understanding of specific problem • Reduce cul-de-sac radii or use central cul-de-sac areas that could be corrected, and a permeable doughnuts (Figure 9-2) lack of statistical significance in Use Onsite • Roof leaders and sump pumps should be recharged onsite database trends. Other things, such as Infiltration Wherever instead of conducted to the storm drain or sewage system Possible • Leave native vegetation between residential lots for sediment depths in the ponds, are privacy and recharge unknown. Stormwater quality, which • Leave stream buffers between residential developments is a serious threat to water quality, has and streams not been compared between • When rezoning, use lowest density residential zoning subwatersheds or sights. Stream possible channel impacts in different portions Clearing/Grading • Develop clearing and grading construction guidelines that Plans minimize site disturbance and vegetation loss of the watershed due to urbanization • Require grading and erosion control plans, and inspect is also unknown. This lack of a same during progress of construction database makes comparison to water Landscaping • Encourage the use of native species for landscaping quality goals in the future difficult. wherever possible • Leave native vegetation in place as a buffer • Use mulched areas for part of lawn 9.2 Recommended • Minimize lawn size and increase native landscaped area Other Onsite • Connect roof leaders and sump pumps to recharge gravel Actions Recharge Methods • Recharge all onsite runoff wherever possible Source: Adapted from Schueler, Fall 1994, Watershed Protection Techniques, V1, N3. Based on the top ten problems “The Importance of Imperviousness” identified above, recommended actions have been developed to Prevention Measures address each problem. For ease of understanding, these are divided into Prevention Method 1: Reduce three categories: 1) prevention; 2) future imperviousness remedial measures; and 3) monitoring. As discussed in findings above, the Pennichuck watershed is currently at a hefty 15% imperviousness overall. This is in spite of the fact that some portions of the watershed, largely in

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Hollis, are mostly undeveloped. and Conservation Commissions to Some subwatersheds, as was shown reduce imperviousness. on Table 9-2, have extremely high imperviousness levels (up to 36%). The most important method to reduce The related water quality that is imperviousness is to require produced from these impervious developers to control runoff from new subwatersheds is poor. subdivisions and to incorporate remedial stormwater measures into Table 9-4. Buffer Zone Requirements existing facilities when they come up Planning 1. Require buffer limits on all clearing/grading and erosion for substantial modification. Stage control plans. 2. Record all buffer boundaries on official maps. This can be done (and has been 3. Clearly establish acceptable and unacceptable uses 4. Establish clear vegetation targets and rules for different elsewhere) by requiring that post- zones of the buffer. development conditions not exceed 5. Provide incentives for owners to protect buffers through pre-development conditions for perpetual conservation easements rather than deed stormwater. During very large storms restrictions. 6. Use level spreaders or other techniques as needed to prevent (greater than ten-year storms) this is channelized flow through the buffer. sometimes not practical but peaks can Construction 1. Pre-construction stakeout of buffers to define the limits of be captured and stored for slow Stage disturbance. release back to the system. In storms 2. Set limits of disturbance based on drip-line of the forested of two year frequency or less, CEI buffer. 3. Conduct pre-construction meeting to familiarize contractors recommends that all runoff be and supervisors with limits of disturbance. infiltrated instead of leaving the site. 4. Mark limits of disturbance with a silt fence barrier, signs or Model bylaws geared towards water other methods to exclude construction equipment. supply protection are included in 5. Inspect the buffer during construction to assure that channelization is not occurring through the buffer. Appendix H. Post- 1. Mark buffer boundaries with permanent signs or fences Development describing allowable uses. Prevention Method 2: Buffer Stage 2. Educate property owners or homeowner associations on the Zones purpose, limits and allowable uses of the buffer. 3. Conduct periodic walkthroughs to inspect the condition of In addition to providing pervious the buffer network. areas for recharge, buffer zones can 4. Reforest grass or lawn buffers. filter poor water quality from highly Source: Adapted from Schueler, Technical Note 7, Watershed Protection Techniques, V1N1, Feb. 1994. urbanized sites such as commercial developments, subdivisions, and To reduce future imperviousness, industrial land uses. prevention measures are needed. Pennichuck Water Works Corporation Although the distance of a buffer for currently tries to work with Planning pollutant removal varies considerably Boards and Conservation from site to site based on site-specific Commissions in the watershed Towns conditions, as outlined in Section 7.0, to encourage Best Management a general guideline would be to use a Practices. However, a more minimum 400’ buffer around the concerted effort needs to be made in chain ponds and a 200’ buffer from this area. Table 9-3 outlines some of the Ordinary High Water (OHW) the most important actions that can be mark from all tributaries and wetlands taken by watershed Planning Boards that are directly tributary to the chain ponds. This is consistent with the Cohen Bill that was recently passed in

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Massachusetts for the protection of network within the watershed. As water resources. This bill prohibits development occurs in the future, alternations to land or building within additional impacts are likely to occur. 200 feet of a tributary or other To minimize these impacts, the waterbody or within 400 feet of a following steps are recommended: reservoir. A summary of the Cohen • Work with Public Works Bill is included in Appendix I. Departments and the State

Department of Transportation to It should be understood however, that avoid direct piping of runoff to a different buffer may be appropriate streams and instead use depending on the site-specific infiltration technologies. Grassed conditions. For example, on steep swales are already used in many slopes a larger buffer may be needed areas, and can provide a very while in some areas where extensive effective water quality infiltration is used and mature native improvement if stormwater is forest is left in place, a lesser buffer allowed to infiltrate. These may be appropriate. In any case, the groups should also be encouraged buffer must not become channelized to use leaching catch basins and provisions must be taken before where possible in their own the development occurs to protect it construction efforts. These have from short-circuiting. been used in many areas,

including along Route 101A, with In order to preserve the integrity of a high level of success and good buffer zones created for the protection results. of water quality, the steps identified in Table 9-4 should be incorporated into the buffer zone requirements.

Additionally, a “demonstration buffer zone” should be developed by Pennichuck Water Works to provide an example for developers, Planning Boards, and Conservation Commissions. This could be done in conjunction with Pennichuck’s review of a commercial or residential development where the developer wishes to perform a community service and stand as an example of environmentally friendly practices while incurring little or no increased cost. Figure 9-1. Commercial Parking Lot Using Infiltration Methods. Prevention Method 3: Minimize Adapted from Schuler, 1994. Transportation Impacts • Work with watershed Fire As noted previously, transportation Departments to address spill impacts are significant because of the number and size of the roadway

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issues and to make them aware of length or planted with low spill potential and critical maintenance, low profile watershed areas. Fire vegetation. If in a wet area, the Departments should be equipped swale might be replaced with a with catch basin covers, pads for small wet pond. The purpose of solvents, caustics and acids, and the demonstration project would booms and pads for petroleum be to show developers, their products. Additionally, the Fire engineers, and Planning Boards Departments should all have and Conservation Commissions maps that show the locations of how roadways can be developed in critical catch basins, or ideally, a more environmentally friendly the most important catch basins method. It could also be used as a should be marked because of the tool to work with Public Works problems with keeping track of Departments in the use of alternate maps during emergency technologies and narrower road conditions. widths than are typically allowed by Public Works Departments.

Prevention Method 4: Education There are a number of education issues that need to be addressed: • Education of general watershed residents on how their actions affect the watershed and how they can help. • Education of school age children as tomorrow’s customers. • Education of planning boards, conservation commissions, public works departments, developers Figure 9-2. Cluster Housing Adapted to Promote Infiltration. and site engineers. Adapted from Schuler, 1994. In order to address these three broad • Develop a monitored classes of people, a multipart program “demonstration roadway” for is recommended, consisting of the comparison to an existing similar following elements. but old style roadway. In conjunction with the 1. Initial educational demonstration buffer zone, questionnaire sent to all Pennichuck should also develop a watershed residents regarding the demonstration roadway that can current status of their knowledge be monitored as part of the and asking questions that will monitoring program discussed in impart information even if the Section 9.3. The roadway should survey questionnaire is never contain items such as a grassed returned. swale mowed to a longer grass

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2. The development of a school age beneficial to protecting the watershed. public education program with Pennichuck should begin the process materials made specifically for of reviewing and revising these the watershed and taught in regulations to incorporate a level of gradewide presentations by a protection should it be needed in the part-time professional teacher or watershed. While most watershed waterworks staff, or incorporated Towns have shown a high level of into the school curriculum. cooperation, the watershed 3. Hold a technical transfer regulations could be used as a backup workshop for Conservation if practices that are detrimental to Commissioners, Planning Board Pennichuck’s water quality can not be members and staff, Public Works modified through discussions and directors and staff, developers and technology transfer. In most cases, site engineers. Many of the however, the use of watershed techniques and principles may be regulations for enforcement of unfamiliar, so it is important to requirements should be avoided. provide educational opportunities Wherever possible, cooperative and to obtain input from affected agreements should be used instead. parties such as developers. The workshop would also allow an Remedial Actions opportunity to discuss cost The remedial actions recommended implications with developers, below address the most highly which are typically minimal or contaminated areas of the watershed. non-existent. In fact, many of the In these areas, less infiltration technologies and expensive/intensive prevention methods described above are measures are ineffective or lower cost than conventional inapplicable. These remedial methods used today. If the measures have been developed based workshop is successful, on specific problem areas identified in Pennichuck could consider Section 9.1 Findings. making it an annual event for as long as important information Remedial Measure 1: Dredging needs to be transmitted to of the Ponds developers. It could also be an opportunity to do onsite visits and It is strongly suspected that the reviews of Pennichuck’s Pennichuck ponds have begun to fill demonstration projects. with sediment due to the high level of 4. Conduct a follow-up stormwater entering the watershed. questionnaire survey to gauge Stormwater is typically laden with the effectiveness of the program sediments, and these are settled out in and develop an understanding of the ponds, which are believed to how attitudes have changed or provide a major improvement to the increased in knowledge. water quality that eventually reaches the treatment plant and Pennichuck’s Prevention Method 5: Modify customers. Some of the ponds show Watershed Regulations particular evidence of filling with sediments, and may even be acting as The existing watershed regulations sources of additional nutrients have few controls that are currently

Page 9- 11 Pennichuck Water Works Watershed Management Plan Section 9.0 Recommendations because of anaerobic conditions and Remedial Measure 2: Infiltration the re-release of nutrients and other Controls at Specific Sites pollutants from the sediments that occurs under anaerobic (without The most developed portions of the oxygen) conditions. Because this site are the Boire Field Brook could drastically accelerate water subwatershed at 36% impervious, the quality deterioration in the watershed, Pennichuck Brook to Bowers Pond maintenance dredging of the ponds is subwatershed (PBB) at 29% probably going to be likely. However impervious, and the Witches Brook the first step in determining where East (WBE) subwatershed at 23% and how much dredging is required is impervious. Note the major to evaluate sediment depths and difference in imperviousness between characteristics. The following steps these subwatersheds and those with are recommended. the least imperviousness, which include Witches Brook South (WBS) 1. Map and probe sediments in each at 5% impervious and the Muddy of the ponds for depth and extent. Brook subwatershed (MB-1) at 6% Take sediment samples for impervious. analysis, and measure water quality at the time of depth probes Although prevention methods are to determine whether bottom recommended for watershed-wide conditions are anaerobic. application, in many of the 2. Calculate total sediment depth subwatersheds that are more and cubic yardage for potential developed there is little new removal. development that can occur. It is thus likely that the prevention methods 3. Identify method of dredging and described above will have the most methods for dewatering dredged impact in maintaining water quality in spoil materials or re-routing water those less developed watersheds, during dry excavation. where they will have a lesser impact 4. Obtain approvals for dredging, in the developed watersheds. The which may be difficult in some more developed watersheds, or those instances. Show Conservation with higher imperviousness, are more Commissions evidence of likely to be affected by remedial extreme need for dredging, if measures. Therefore, it is these sediment depth probes show that subwatersheds that are most it is necessary. appropriate for the use of structural Best Management Practices (BMPs). 5. Continue to monitor ponds on a yearly basis, monitoring sediment These technologies are appropriate depths at a specific location near for projects that come back to the the outlet of each pond. Use this Planning Board for substantial to determine when maintenance modification of existing facilities, or dredging is required. expansion of those same facilities, or as stand alone units such as the one developed by Pennichuck for New Hampshire Technical College.

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An additional structural BMP was expedited if water supplies are at risk. created for the Pennichuck Square We recommend that Pennichuck area. Both of these BMPs are located request a status report on each of the within the most impervious sites. Their status at the time of this subwatershed of Boire Field Brook. report is recorded in that information, An additional structural BMP within however, at least an annual discussion this area that should be considered is with each of the project managers at one to control runoff from the airport. DES on each of the sites should be Airports are well known for their conducted to make sure that DES is contribution of spills of aviation fuel, aware of Pennichuck’s Watershed oil and deicing chemicals to Protection Program and that waterways. Additionally, they Pennichuck is aware of DES’ most commonly produce a heavy nutrient recent actions on the site. load and heavy metal load from the same sources as found on other types Remedial Measure 4: Hot Spots of roadways. This type of land use Hot spots are defined in this report as essentially presents itself as a huge service stations, car dealerships and parking lot, and the impacts on local automotive repair shops. Because of waterways can be significant. We recommend that Pennichuck work Table 9-4 with the Boire Field authorities to Remedial Measures Priority Subwatersheds develop a BMP that will assist in Rank Designation Name Location Impervious reducing the impacts of this airstrip 1 BFB Boire Field Nashua 36% on Pennichuck’s water supply. Once Brook all the BMPs are completed in the 2 PBB Pennichuck Merrimack 29% most highly impervious Brook to & Nashua Bowers subwatershed, the next most highly Pond impervious subwatershed (PBB- 3 WBE Witches Amherst/ 23% Pennichuck Brook to Bowers Pond) Brook East Hollis should be addressed. 4 WBN Witches Amherst/ 19% Brook Milford North By addressing the most impervious 5 SPB Stump Amherst/ 17% watersheds with remedial measures, Pond Merrimack steps can be taken each year to reduce Brook the impact of these most impervious areas on water quality. A ranking of the potential of these particular types the areas in terms of appropriateness of businesses to create major water for remedial measures is given on quality impacts on the system as a Table 9-4. whole, special educational efforts are warranted. Service stations can Remedial Measure 3: generate significant hydrocarbons, Hazardous Waste Sites metals, and other pollutants from car There are a number of hazardous washing, engine steam cleaning, spills waste sites in the watershed, some of oil and gas, parts cleaning, leakage more benign than others. These sites from wrecked vehicles and exposure are in various stages of remedial of automotive products and waste to action being required by DES, but stormwater. Since most floor drains these processes can often be can no longer be connected to the

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sanitary sewer, many gas stations annual basis based on the amount of discharge these materials either imperviousness added in each directly to storm drains or recharge subwatershed. There are several onsite. Neither of these is acceptable methods to estimate this, which could and in fact are illegal in areas defined include additional land use mapping as “underground sources of drinking or aerial photography, or the water”. Some of the recommended development of town by town pollution prevention practices “imperviousness” budgets that could be calculated by Planning Boards Table 9-5 after each calendar year. Several Recommended Practices to Prevent Stormwater locations along the main stream Pollution from Service Stations/Auto Repair Areas channel should also be selected to 1 Prevent discharges when changing automotive fluids survey in channel characteristics. 2 Use drip pans when working on engines This could then be measured on an 3 Use special care to prevent leaks from wrecked vehicles annual basis, or alternatively, aerial 4 Quickly cleanup spills of all sizes photographs could be used to 5 Keep wastes from entering floor drains and storm drains calculate annual changes in key 6 Use concrete surfaces and roofing over fueling areas to subwatersheds. prevent spilled fuel from contact with stormwater 7 Properly store and recycle used batteries Monitoring Technique 2: 8 Clean parts without using liquid solvents (or use solvent Periodic Sediment Depth recyclers) Mapping 9 Capture all metal particles during grinding and finishing operations As described in Remedial Measure 1, 10 Properly store and recycle waste oil, antifreeze and other sediment depth mapping of the ponds automotive fluids is needed to evaluate their current 11 Select “environmentally friendly” products and control status. This should also be continued inventory to reduce wastes on an annual or bi-annual basis to 12 Keep all working areas inside and away from stormwater determine the rate of accumulation. 13 Treat all liquid streams from car washing and engine cleaning Monitoring Technique 3: 14 Train employees on pollution prevention activities for the shop Stormwater Monitoring of 15 Educate customers on proper recycling and/or disposal of Demonstration Projects automotive products The demonstration projects already undertaken by Pennichuck should be identified by the Santa Clara Valley monitored upstream and downstream Non-Point Source Control Program for at least three storms per year to are listed in Table 9-5. evaluate the effectiveness of the measures. This should also be done Monitoring at the demonstration buffer project and the demonstration roadway Monitoring Technique 1: projects when completed. This pre- Measure Stream Channels and and post-monitoring of control areas Imperviousness Annually and up and downstream areas of the demonstration projects will allow for The imperviousness estimates made corrections to be made if necessary for this project, which was shown on and will demonstrate the effectiveness Table 9-2, should be updated on an of the methods.

Page 9- 14 Pennichuck Water Works Watershed Management Plan Section 9.0 Recommendations

Monitoring Technique 4: recommended for analysis are Intensive One Year Monitoring provided below: Program ❏ Ammonia nitrogen - This is the Because there is little water quality nitrogen form most readily used baseline for the watershed, a baseline- by aquatic plants. Nitrogen may monitoring program should be contribute to excess vegetative developed over a one-year period. growth in a water system. High levels of ammonia nitrogen may Dry Weather Monitoring indicate a nearby source of waste The purpose of a monitoring program discharge or fertilizer storage. A is to provide critical long-term method detection limit of 0.05 trending information for the chain mg/l may be used for ammonia ponds and their tributaries. The data nitrogen analysis. obtained from the monitoring plan ❏ Chloride - Chlorides may be will identify the current in-pond water introduced to runoff after salts are quality and assist in evaluating the applied to remove ice and snow impacts of the surrounding watershed from roads, parking lots and on the chain pond system. sidewalks. At high levels, chlorides can be toxic to fresh Since there is very limited data on water organisms. A field probe watershed water quality, it is may be used for measurement. recommended that a monitoring ❏ Dissolved oxygen* - Dissolved program be implemented with oxygen levels will indicate if monthly monitoring including depth bottom sediments have an oxygen sampling in each of the ponds and demand. A field instrument tributary sampling in each should be used and calibrated subwatershed. It is recommended that before the readings are taken. three samples be taken at each pond High dissolved oxygen levels to establish whether in-pond may cause algal blooms, which sediments may be providing a source can lead to fish kills, and other of phosphorus and other chemical undesirable water quality effects. loadings to the ponds and to provide ❏ Fecal coliform* - Indicator of more information on possible disease causing pathogenic corrective methods. Only ponds that organisms. The laboratory should show stratification should be sampled use the membrane filter method. in this way. Shallow ponds (typically The presence of fecal coliform is less than 10 feet deep) that don’t typically an indication of nearby stratify should be sampled at top and feces from animals or humans. bottom only, in the deepest section of ❏ Nitrate - A method detection limit the pond. The first should be taken at of 0.05 mg/l may be used for the water surface in the epilimnion nitrate nitrogen. High nitrate layer. The second should be taken in levels may indicate contamination the metalimnion layer, and the third from fertilizer, municipal should be taken a few inches from the wastewaters, feedlots, or septic bottom of the reservoir in the systems. hypolimnion layer. The parameters ❏ pH* - A field probe may be used for measurement. Over-

Page 9- 15 Pennichuck Water Works Watershed Management Plan Section 9.0 Recommendations

productive reservoirs or ponds sampling container for the lower may see fluctuations in pH as detection limit. vegetation photosynthesize and ❏ Total suspended solids (TSS)* - respire. TSS are carriers for phosphorus ❏ Specific conductivity - Specific and other contaminant sources. A conductivity is a field field probe may be used for measurement of the amount of measurement. particulate within a sample. A ❏ Turbidity* - Elevated turbidity field probe may be used for levels can interfere with measurement. Conductivity is disinfection by sheltering also a measure of total dissolved microbes and reducing their solids, which are carriers for exposure to chlorination, contaminant sources in water. potentially allowing disease ❏ Temperature* - Temperature can causing pathogenic organisms to be used to identify the epilimnion, enter the distribution system. A metalimnion and hypolimnion field probe may be used for layers in the reservoir depth measurement. samples. A field probe may be used for measurement. Variations *Analyzing the chain ponds at these in temperature may be an depths for the parameters indicated indication of wastewater above with an asterik (*), will help discharges. establish whether there is a ❏ Total dissolved solids (TDS) - phosphorus loading from the TDS are also carriers for sediments of the ponds. phosphorus and other contaminant sources. A field In addition to the pond depth probe may be used for sampling, it is recommended that measurement. quarterly sampling be conducted at ❏ Total Kjeldahl nitrogen (TKN) - A seven tributaries to assist in method detection limit of 0.20 determining the impacts the mg/l may be used for TKN surrounding watershed has on the analysis. High TKN values may chain pond system. indicate the presence of a nitrogen source such as a feedlot or It is recommended that each of these wastewater discharge. samples be analyzed for the ❏ Total phosphorus* - This is the parameters indicated in the list above. limiting nutrient in a fresh water Additionally, flow rates should be system and may result in excess taken from all streams monitored. algal growth if present in Review of the long-term monitoring sufficient quantities. A method data over a few sampling runs may detection limit of 0.01 mg/l allow for the reduction of some should be used for total parameters such as nitrate-nitrogen. phosphorus analysis. The laboratory should be contacted Stormwater Monitoring before sample collection to see if To evaluate the degree of pollution they can analyze to this detection associated with stormwater in this limit. They may require a larger watershed, a wet weather sampling program using a “cluster” design was

Page 9- 16 Pennichuck Water Works Watershed Management Plan Section 9.0 Recommendations developed. Sampling locations were (approximately one to two inches chosen to collect stormwater runoff of water in pipe). from various types of land uses within 3. An acid washed bucket will be the watershed including residential, used to collect the sample from industrial and commercial. Both the drainpipe. Buckets will be stormwater drainage maps and land rinsed three times between use maps were used in choosing the samples. Samples will be locations. Sampling locations in each gathered in an acid washed bucket land use were chosen based on the and distributed in appropriately stormdrain pipes that drained the labeled containers. largest area to ensure enough flow for 4. The following field parameters the analysis. Sampling locations are should be taken at each sample: identified in the appendix. • Time • Flow rate The equipment needed to complete • Depth of water in pipe the sampling will include plastic gloves (no zinc), acid washed • Diameter of pipe sampling bottles, acid washed pail, 5. Samples will be taken every 30 stop watch, watch (with minute hand) minutes for two hours. A total of and rain coats, which are discussed in four samples per site should be taken. more detail under the sampling procedure. All samples should be analyzed for: It is important to have reasonable ❏ Total Phosphorus weather data to properly plan for ❏ Nitrogen (TKN) stormwater sampling. Storm notification can be obtained from the ❏ Heavy metals including lead, copper, zinc, chromium and Channel 9 Manchester Weather cadmium Station WMUR at (603) 669-9999, or ❏ Chloride from National Weather Service in ❏ Total Suspended Solids Gray, Maine (One Weather Lane, PO ❏ Volatile Suspended Solids Box 1208, Gray, ME 04039-1208) with real time radar at (207) 688-3216 ❏ Oil and grease ❏ Conductivity from 7:00 am to 5:00 pm. The ❏ pH National Weather Service in Gray, ❏ Total Coliform Maine is the most accurate and can ❏ Fecal Coliform usually predict a storm one to two hours before rain starts.

The procedure for collecting stormwater samples should be as Late summer (July/August) sampling follows: is recommended to provide a worst 1. Teams of two people will be on case event, preferably after a week site at least 30 minutes before rain long dry period so contaminants are starts. All team members should built up on surfaces. wear zinc free gloves to prevent sample contamination. 2. Sampling will begin when the flow of water starts

Page 9- 17 Pennichuck Water Works Watershed Management Plan Section 9.0 Recommendations

An alternative to this type of labor- locations should then continue for the intensive sampling would be to install long-term, using a quarterly baseflow a datalogger at specific locations, monitoring, and periodic stormwater potentially with a sampler. However, monitoring of demonstration projects not all parameters can be measured and key areas identified during the with this method. baseline program. This program would then continue indefinitely, Monitoring Technique 5: Follow- updated annually to determine the up Monitoring effects of the Watershed Management Program on water quality. It can also Once the one year intensive baseline be used to monitor the progress in of dry weather and stormwater meeting the overall goals and monitoring has been completed, trend objectives of the project. graphs can be developed and evaluated. Some parameters may be dropped, others could potentially be added. The monitoring in the same

Page 9- 18 Pennichuck Water Works Watershed Management Plan Appendix A Soil Map and Legend

Appendix B Historical Sampling Data and Location Map -e 281 6 8 6 <1 6 <1 2 14 1 6 8 <100 22 <10 100 <1 3 300 <10 100 12 230 10 11 4 84 100 6 1 8 80 <10 4 <10 70 113 200 200 8 90 140 40 40 14 10 100 <1 4 10 252 <100 3 7 30 26 <100 800 66 26 210 14 <10 3 200 <1 4 <1 158 87 7 18 0 40 100 26 1 <1 30 36 160 14 tntc 20 24 28 20 0 8 2 8 1 120 82 1 tntc 20 8 20 40 22 <1 10 10 <10 6 16 Average 2 20 100 20 >200 60 98 6 30 <10 <1 9 49 19-Dec 14 207 100 78 0 10 2-Dec >200 <1 100 40 34 17 13 tntc 18-Nov 40 92 tntc 6 90 8 46 2 20 <1 43 13-Nov 200 tntc 1 <1 25 21 100 4-Nov 1 53 0 <10 3 tntc 1 29-Oct 0 <10 <100 25 17 300 21-Oct 17 <100 300 0 6 0 517 157 1 9-Oct 3 0 38 tntc 15 760 40 24-Sep 4.00 179 1 10-Sep 1 2 60 tntc 14 210 60 5-Sep 22 <10 2 0 5 28-Aug 2 tntc 2 30 10 21-Aug 17 2 60 13-Aug 22 0 29.00 89 tntc 6-Aug 3 110 33 70 4.00 4 30-Jul 12 24 4 530 24-Jul 0 0.00 5 18-Jul 0 600 4 5 16-Jul 20.00 1 400 9-Jul 33.00 4 305 2-Jul 260 0 25-Jun 0.00 tntc 20-May tntc 13-May 0.00 tntc 8-May 97.00 1-May 25-Apr 16-Apr 9-Apr 8Mr20 1 2 1 tntc 26-Mar 18-Mar 12-Mar 2Fb05 0 12-Feb 0Jn02 3 7 0 1 0 30-Jan 23-Jan 17-Jan

268.5 River 019440010700520

Harris Pond . 716. 782. 70.3 22.2 87.8 69.7 27.1 4.9 013036516 Fecal ColiformData1991 Bowers Pond

Holt Pond

Amherst Street

Supply Pond

Muddy Brook

151.7 Witches Brook

7775.8 57.7 Stump Pond 4

Nevins Road Average 3My< <1 <1 27-May 13-May 1Ag< nc54 62 10 4 40 20 63 4 76 200 910 40 <100 280 <1 5 13 50 tntc 320 18 2 30 5 32 4 <1 5 <1 800 60 25-Aug 18-Aug 11-Aug 5Mr< <1 <1 <1 <1 <1 25-Mar 18-Mar 10-Mar 9Ar< <1 <1 <1 <1 <1 <1 29-Apr 22-Apr 15-Apr 6Fb< <1 <1 <1 <1 <1 <1 26-Feb 19-Feb 11-Feb 6Sp1114 <1 42 30 34 1 2 20 14 1 <1 1 <1 20 22-Sep 16-Sep 3Ot8 131 032 21 6 11 82 24 3 30 18 3 <1 80 13-Oct 0Jn< 82< 0 12 4 12 16 4 108 20 <1 176 156 2 120 76 2 68 24 24 4 tntc 24 4 tntc 4 4 1 26 <1 <1 100 <1 30-Jun 23-Jun 16-Jun 8Jn< <1 <1 <1 <1 <1 1 28-Jan 22-Jan 14-Jan -u 01421 02 0184 10 20 40 2 10 2 4 1 40 4-Aug -a 1<1 <1 3-Mar 8Jl< 11 0< 17 124 54 <1 48 7 76 81 64 <1 64 20 <1 tntc 1 10 tntc 24 tntc 4 1 tntc 10 1 5 <1 11 <1 <1 820 20 28-Jul 21-Jul 14-Jul -p 1<1 <1 <1 2 8-Apr 1-Apr -e 1<1 <1 5-Feb -e 01913 03 228 4 22 28 30 100 30 140 1 3 30 20 1 6 9 3 1 12 20 60 8-Sep 1-Sep -c 134< 162 <10 23 6 <1 <1 4 3 <1 1 6 6-Oct -u 701 8148 0 24 4 <1 48 <1 72 tntc 100 <1 9 tntc 88 <1 104 <1 48 <1 13 tntc 1700 3700 9-Jun 2-Jun -a <1 1 7-Jan -u 0< 235 85 313 13 52 28 2 54 3 22 <1 80 7-Jul

417.1 River 23681228821014

568365.4 8.3 15.6 Harris Pond Fecal ColiformData1992 Bowers Pond

Holt Pond

119.2 Amherst Street

8281 28.2 Supply Pond

Muddy Brook

143.4 Witches Brook

0636.8 20.6 Stump Pond

Nevins Road Average 5My1 1< 42 18 82 30 28 18 80 <1 20 54 <1 <1 18 25-May 7Ag7/2161 87 18 20>200 >200 620 88 540 >200 81 60 390 10 78 <100 18 10 16 10 116 32/60 30 4600/1700 19-Aug 30 77/72 18-Aug 20 17-Aug 20 12-Aug 11-Aug 10-Aug 3Jn2 6014 34 37 24 0 20 44 79 13 39 1 11 40 36 1 18 0 1 26 24 77 30-Jun 23-Jun 16-Jun -u 0/0 20>0 2>0 20>0 20>0 >200 >200 >200 >200 >200 >200 12 100 >200 120/100 9-Aug >200 290/300 6-Aug 200/400 5-Aug 500/180 4-Aug 3-Aug 1Jl1 43 4121>0 2 20>200 >200 >200 >200 123 >200 >200 >200 3 1 >200 182 32 64 1 35 3 64 144/82 200/500 30-Jul 15 68/62 29-Jul 28-Jul 21-Jul 15-Jul -u 1< 1< 153< 5 17 <1 67 3 6 5 111 8 <1 6 34 <1 53 <1 0 <1 1 11 52 8-Jun 2-Jun -u 10>0 203 3155 >200 59 115 93 33 >200 >200 0 21 2 8-Jul

226.7 River 0000000000 0000001000

842. 558. 35.9 84.2 35.5 20.2 38.4 Harris Pond Fecal ColiformData1993 Bowers Pond

Holt Pond

Amherst Street

Supply Pond

108.7 Muddy Brook

72.0 Witches Brook

1. 133.3 116.5 Stump Pond

Nevins Road Average 4My8663 66 68 216 22 82 66 68 66 34 6 6 8 24-May 0Ag10<0 110<0 02 106 0<100 20 60 <100 20 10 <100 100 <1 100/<100 30-Aug 6Ag8 163 20< 08418 4 8 50 <1 >200 30 6 tntc tntc <1 <1 82 1570/1350 23-Aug 16-Aug 9Jn4413 141 24 32 94 >200 16 48 16 4 82 28 <1 86 66 2 12 94 56 34 140 48 52 1 12 8 4 74 2 4 82 72 29-Jun 22-Jun 15-Jun -u 1 194 094 4 2020 24 >200 140 8 40 >200 9 42 20 <1 40 >200 >200 9 <1 <1 <1 110 50 9-Aug 2-Aug 9Jl1 07 14 8648 56 138 6 20 4 98 8 4 44 >200 60 <1 8 4 72 >200 20 >200 20 14 6 6 6 8 >200 14 10 12 152 26-Jul 19-Jul 12-Jul -e 09 11 01 1 2 010 10 <20 <10 12 10 10 <1 40/90 7-Sep -u 12 81 21 61 82 156 10 106 26 36 10 150 22 <1 18 78 28 66 24 34 <1 >200 30 8 9-Jun 2-Jun -u 0827 20< 69 0 50 100 96 56 <1 >200 78 2 8 80 8-Jul

145.3 River

234. 79.6 45.6 32.3 Harris Pond Fecal ColiformData1994 Bowers Pond

Holt Pond > 0/0 nctt 02 1580 20 30 tntc tntc 200/100

103.9 Amherst Street

689. 8339.1 58.3 92.6 46.8 Supply Pond

Muddy Brook

Witches Brook

Stump Pond

162.2 Nevins Road Appendix C 1996 Sampling Data Average 5My7 14 001 000010 40 0 300 0 0 10 20 10 160 100 0 400 10 250 2 0 42 0 31 0 75 30-May 15-May 5Ar< <1 <1 25-Apr 6Jn20000100000300 310 100 0 200 200 0 0 0 100 0 100 100 0 0 100 0 0 0 0 200 0 26-Jun 13-Jun -a 0122 03 23 10 30 12 1 1 6 30 20 20 2 1 60 1-May 9-Jul

58 .773 62.00 7.33 4.57 55.83 River 000020010000 1001000

Harris Pond

Bowers Pond Fecal ColiformData1996 Holt Pond 121.67 Behind NHVT

50 60 .305 60.00 0.50 4.43 46.00 55.00 Amherst Street

Pennichuck Brook

Supply Pond

Springs

Muddy Brook 156.67 Witches Brook

26.67 Stump Pond 3Jn01 .500 .700 .40.03 0.09 0.04 0.09 0.04 0.07 0.12 0.07 0.09 0.21 0.09 0.06 0.01 0.06 0.06 0.04 0.04 0.23 0.09 0.05 0.14 0.10 Average 9-Jul 26-Jun 13-Jun 0My.2.6<0/0 .1.2.2.500 0/0 0/0 0/0 .1<0 0.01 .01/.03 <.01 <.01 .01/.04 .01/.04 .01/.03 .01/.02 0.04 .01/.01 0.02 .02/.05 <.01/.02 <.01/.01 .01/.04 .02/.06 30-May .02/.05 15-May 5Nv00 .1.2<0 .1<0 0.01 <.01 0.16 0.02 0.01 0.01 0.01 .02/<.01 .02/.01 <.01 0.02 0.08 0.06 15-Nov 14-Nov 7Ar00 .2 .20.04 0.02 0.025 0.02 17-Apr -a .100 .500 0.05 0.07 .02/.05 0.02 0.01 0.55 0.18 0.06 0.03 0.11 0.04 2-May 1-May

River

Harris Pond

0.12 Bowers Pond Phosphorus Data1996

.500 .400 .3<0 .10.01 <.01 <.01 0.03 0.06 0.04 0.05 0.05 Holt Pond

Behind NHVT

Amherst Street

Pennichuck Brook

Supply Pond

Muddy Brook

Witches Brook

Stump Pond Summary of 1996 Sampling Parameters

ph Conductivity Turbidity DO (% saturation) Temperature Flow Date 7/17/1996 8/28/1996 12/5/1996 7/17/1996 8/28/1996 12/5/1996 7/17/1996 8/28/1996 12/5/1996 7/17/1996 8/28/1996 12/5/1996 7/17/1996 8/28/1996 12/5/1996 7/17/1996 8/28/1996 12/5/1996 SW-1 7.87 7.49 4.62 165 607 216 8 NA 0 7.6 9 6.8 23.3 22 7.6 dam dam dam SW-2 7.77 10.4 4.6 132 567 132 7 NA 28 7.34 11.9 6.3 23.1 22.5 2.5 dam dam dam SW-3 7.4 8.02 4.42 276 617 285 16 NA 0.5 7.66 7.68 4.8 22 19.2 3.7 0.35 nfd 0.181 SW-4 7.66 8.63 4.45 119 186 112 8 NA 15.1 7.04 10.8 7.2 24.1 22.2 2.4 dam dam dam SW-5 7.48 8.69 4.27 115 161 112 10 NA 8.4 7.48 10 4.4 23.5 22.1 3.2 nfd visible visible SW-6 7.2 9.09 4.09 100 233 88 7 NA 6.7 7.71 6.09 4.4 22.8 20.7 2.9 dam dam dam SW-7 6.97 8.95 4.38 105 209 112 10 NA 2.2 7.85 7.15 4 22.5 20.4 3 nfd nfd nfd visible visible visible high high high SW-8 7.61 10.8 4.11 106 215 93 9 NA 5.6 7.02 9.52 2.9 27.8 23.3 3.6 flow flow flow visible visible visible high high high SW-9 6.92 9.57 4.08 93 161 84 23 NA 0.8 6.69 10.6 2.8 27.8 23.5 1.9 flow flow flow SW-10 7.01 8.59 4.34 141 231 152 11 NA 4.9 7.56 3.26 3.1 24.2 20 3.7 0.12 nfd 0.194 SW-11 7.27 8.79 4.28 96 155 67 11 NA 6.5 8.41 9.03 3.3 21.6 19.9 3.3 0.13 nfd 0.152 SW-12 7.05 10.1 4.3 91 108 75 11 NA 11.7 8.27 9.93 4.4 24.4 19.2 3.5 visible nfd visible SW-13 7.26 9.78 4.28 87 140 53 9 NA 2.8 9.13 9.7 3.7 20.6 18.6 3.4 0.17 0.008 0.173 Summary of 1996 Water Quality Data Laboratory Analysis

Fecal Coliform (# per Total Phosphorus 100 ml) Ammonia (mg/l) TKN (mg/l) (mg/l) Nitrate (mg/l) Date 7/17/1996 8/28/1996 12/5/1996 7/17/1996 8/28/1996 12/5/1996 7/17/1996 8/28/1996 12/5/1996 7/17/1996 8/28/1996 12/5/1996 7/17/1996 8/28/1996 12/5/1996

SW-1 Supply Pond Dam <100 3.1 6 <0.50 <0.50 <0.1 <1.0 <1.0 0.39 0.003 0.19 0.44 <0.50 <0.50 0.52

SW-2 Harris Pond Dam <100 2 11 <0.50 <0.50 <0.1 <1.0 <1.0 0.3 0.046 0.12 0.28 <0.50 <0.50 0.43 SW-3 Boire Field Brook 310 144.5 105 <0.50 <0.50 <0.1 <1.0 <1.0 0.59 0.125 1.35 0.31 0.53 <0.50 0.74

SW-4 Bowers Pond Dam <100 3.1 13 <0.50 <0.50 <0.1 <1.0 <1.0 0.3 0.016 0.29 0.33 <0.50 <0.50 0.42

SW-5 Bowers Pond Mid <100 13.7 37 <0.50 <0.50 <0.1 <1.0 <1.0 0.3 0.026 4.53 0.48 <0.50 <0.50 0.42 SW-6 Holts Pond Dam 100 13.7 12 <0.50 <0.50 <0.1 <1.0 <1.0 0.3 0.049 0.13 0.47 <0.50 <0.50 0.39 SW-7 Pennichuck Brook 100 78.2 13 <0.50 <0.50 <0.1 <1.0 <1.0 0.3 0.18 0.04 0.14 <0.50 <0.50 0.39 SW-8 Pennichuck Pond Mouth <20 1 5 <0.50 <0.50 <0.1 <1.0 <1.0 0.3 0.023 0.06 0.23 <0.50 <0.50 0.39

SW-9 Muddy Brook 40 2 18 <0.50 <0.50 <0.1 <1.0 <1.0 0.3 0.082 0.01 0.32 <0.50 <0.50 0.42

SW-10 Stump Brook 300 >200.5 39 <0.50 <0.50 <0.1 <1.0 <1.0 0.44 0.043 1.05 0.09 <0.50 <0.50 0.55 SW-11 Witches Brook 300 109.1 6 <0.50 <0.50 <0.1 <1.0 <1.0 0.3 0.03 <0.01 0.45 <0.50 <0.50 0.5 SW-12 Witches Brook 200 >200.5 31 <0.50 <0.50 <0.1 <1.0 <1.0 0.3 0.013 0.4 0.99 <0.50 <0.50 0.51 SW-13 Witches Brook <100 34.4 29 <0.50 <0.50 0.5 <1.0 <1.0 0.65 0.009 1.19 0.09 <0.50 <0.50 0.5 Appendix D Hydrologic Analysis HYDROLOGY

Runoff Calculations The estimated runoff from the total watershed for a series of varied conditions was determined by analyzing available precipitation and runoff records for the local. Precipitation records for Nashua were used, covering the period 1922-1995, a 74-year continuous period of monthly rainfall. These were analyzed for the total period and for two distinct periods, 1922-1965 (44 years) and 1966-1995 (30 years), as discussed below. The runoff estimates for the area were based on analysis of several gaging station records as obtained by the U.S. Geological Survey as discussed below.

Although long term precipitation records are most useful in watershed studies, the long term record must be broken into several periods of 30 to 40-year duration so that trends of wet or dry periods can be examined. The U.S. Weather Bureau bases its precipitation averages for a given location on 30 consecutive years of record, usually through the most recent decade ending in zero; this means current averages by the U.S. Weather Bureau are based on the period, 1961-1990. Since monthly precipitation values are available through 1995, this study considers the 30-year period, 1966-1995, so that the most recent records are included. The average, maximum and minimum precipitation values for each month of the year are given for three distinct periods (44-year, 30-year and 74-year period) in Table 1-1.

Examination of this table reveals that the 44-year period from 1922-1965 was somewhat drier than the 30-year period from 1966-1995. This is evidenced by the fact that the average monthly precipitation was greater during the latter period for 11 of the12 months (only January was greater in the 1922-1965 period). The average precipitation was more than 8% higher for the most recent 30-year period versus the 44-year period.

Further analysis of the 30-year period from 1966-1995 revealed that the wettest year occurred in 1983 with a total precipitation of 59.72 inches, while the driest year occurred in 1966 with a total precipitation of 33.23 inches. Table 1-2 shows the average monthly precipitation values for the 30-year period, and the monthly precipitation values for the wet and dry year within the 30-year period.

Analysis of the entire 74-years of precipitation records shows that 1983 was the wettest year in the 74 years of record. However, the dry year for this period occurred in 1941 when only 27.33 inches of precipitation were recorded. The driest three consecutive years occurred in the mid-1960’s drought with the following annual precipitation values:

❑ 1964 31.13 inches ❑ 1965 27.56 inches ❑ 1966 33.23 inches Three-year total 91.92 inches

Table 1-1. Precipitation Analysis for the Nashua Area

44-year Period 30-year Period 74-year Period Month 1922-1965 1966-1995 1922-1995 Total Average Maximum Minimum Total Average Maximum Minimum Total Average Maximum Minimum Jan 151.52 3.44 7.54 0.74 92.64 3.09 10.50 0.60 244.16 3.30 10.50 0.60 Feb 125.95 2.86 5.93 1.05 95.02 3.17 8.07 0.07 220.97 2.99 8.07 0.07 Mar 153.81 3.50 9.64 1.38 112.32 3.74 9.81 0.56 266.13 3.60 9.81 0.56 Apr 153.54 3.49 6.26 0.48 108.92 3.63 9.51 0.93 262.46 3.55 9.51 0.48 May 139.34 3.17 9.34 1.07 106.34 3.54 7.20 0.92 245.68 3.32 9.34 0.92 June 151.48 3.44 8.66 0.86 112.65 3.76 9.00 0.90 264.13 3.57 9.00 0.86 July 144.08 3.27 9.21 0.75 104.32 3.48 6.27 0.45 248.40 3.36 9.21 0.45 August 145.04 3.30 8.21 0.98 111.45 3.72 9.46 0.70 256.49 3.47 9.46 0.70 Sept 147.81 3.36 11.53 0.11 104.60 3.49 7.42 0.70 252.41 3.41 11.53 0.11 Oct 138.04 3.14 10.21 0.50 106.71 3.56 7.28 1.04 244.75 3.31 10.21 0.50 Nov 174.26 3.96 8.33 0.63 132.15 4.41 8.82 1.28 306.41 4.14 8.82 0.63 Dec 145.03 3.30 7.26 0.75 122.00 4.07 8.84 0.91 267.03 3.61 8.84 0.75 Totals 1769.90 40.23 1309.12 43.66 3079.02 41.61

NOTE: All values given in inches Table 1-2 - Annual and Monthly Precipitation for the Nashua Area (Based on 30-year Record at Nashua for Period 1966-1995)

Average Maximum Year Minimum Year Month Precipitation in 30 = 1983 in 30 = 1966 (inches) (inches) (inches) January 3.09 5.71 3.79 February 3.17 4.64 3.02 March 3.74 9.81 1.98 April 3.63 7.06 0.93 May 3.54 4.74 2.84 June 3.76 3.22 1.33 July 3.48 2.39 2.64 August 3.72 2.75 1.12 September 3.49 1.05 5.44 October 3.56 3.57 3.53 November 4.41 8.92 3.87 December 4.07 5.96 2.74 Total 43.66 59.72 33.23 The average precipitation during this three-year period was 30.64 inches.

The runoff values used for the Pennichuck watershed were derived from a study of records compiled by the U.S. Geological Survey from certain continuous record streamflow monitoring stations. U.S.G.S. operated a gaging station on the Souhegan River at Merrimack, N.H. from 1909 to 1976, at which time the station was discontinued. Subsequently, a gaging station was established on Beaver Brook at North Pelham on the Pelham-Windham town line that has provided a continuous flow record since 1986 to the present day. Although this suggests a ten-year gap in recorded flow data, the period of record for the Souhegan was sufficient to derive relationships between flow data recorded and monthly and annual precipitation. These relationships were correlated with the ten years of data collected since 1986 on Beaver Brook to provide reliable monthly rainfall- runoff relationships. Since the Souhegan River had a drainage area of 171 square miles at its gaging station as compared to Beaver Brook with a drainage area of 47.8 square miles at its gaging station, comparisons of flow records were made on a unit discharge basis. This provides flow rates per square mile of drainage area.

Precipitation-Runoff Analysis

A study of annual precipitation at Nashua and flow data at the Souhegan River at Merrimack for the 54-year period (1923-1976), shows a very distinct relationship between precipitation and flow contribution as depicted in Figure 1-1. All but five of the 54 data points from the 54-year period of record fall within the 90% probability range noted on the figure. This figure can be used to estimate the annual runoff from the watershed given a value for precipitation. For example, the average annual precipitation of 43.66 inches for the 30-year period (1966-1995) would be expected to yield an average runoff value of 25.65 inches with a 90% probability that the annual rainfall producing this contribution would fall within the range of 37.8 to 49.5 inches. A frequency analysis for this 54-year period of rainfall shows the results of Table 1-3.

The rainfall-runoff relationship for the Nashua area was determined by comparing the average and ranges of precipitation and flow for the Beaver Brook period of record (1987-1995) with the Souhegan River period of record (1923-1976). This comparison shows that for the period 1987-1995 the average annual precipitation for the Nashua area was 42.36 inches, which is 1.30 inches (3.0%) less than the 30-year average (1966-1995). The average runoff for the same 1987-1995 period based on Beaver Brook records was 21.12 inches, or about 17% less than the runoff developed for the 54-year period (1923- 1976) using the Souhegan River records. Comparison of the two runoff records showed that the Beaver Brook record fell within the 90% probability range developed from the Souhegan River records for all annual precipitation values less than 50 inches. This agreement suggests that monthly precipitation-runoff values could likely be developed from the Beaver Brook data available for the past decade.

Table 1-3. Frequency Analysis of 54-year Period of Precipitation Percent of Time Amount of Annual Precipitation (inches) Precipitation is Less Than Stated 1% 27.5 2% 28.8 5% 30.9 10% 32.9 20% 35.4 30% 37.2 70% 44.5 80% 47.2 90% 50.5 95% 54.0 98% 57.8 99% 60.2

The monthly precipitation-runoff values developed from the Beaver Brook flow data and Nashua precipitation data resulted in discharge coefficients for each month that reflect seasonal and climatic affects on the relationships. For example, during the months of March and April, when runoff from rainfall and snowmelt can often exceed the precipitation for a given period, the monthly coefficient would range from 88% to 104% of rainfall in an average year. Similar rainfalls of 3.5 to 3.7 inches occurring in July through September would only average from 10% to 25% of rainfall appearing as runoff. Expected monthly runoff values, based on the long-term monthly average precipitation, are shown on Table 1-4. Discharge coefficients and runoff values, based on a wet (1983) and dry (1966) year are also shown on this table. The coefficients result in a calculated runoff value of 28.87 inches for 1983 (48.3% of rainfall) and a calculated runoff value of 15.39 inches for 1966 (46.3% of rainfall). Even in the wettest and driest year for the 30- years, the runoff ratio as a percentage is close to the 30-year average of 45.9%.

Table 1-4. Rainfall - Runoff Relationships for the Nashua Area

Average Year Maximum Year = 1983 Minimum Year = 1966 Precipitation Discharge Runoff Precipitation Discharge Runoff Precipitation Discharge Runoff Month (inches) Coefficient (inches) (inches) Coefficient (inches) (inches) Coefficient (inches) Jan 3.09 0.63 1.95 5.71 0.26 1.48 3.79 0.46 1.74 Feb 3.17 0.56 1.78 4.64 0.42 1.95 3.02 0.58 1.75 Mar 3.74 0.88 3.29 9.81 0.62 6.08 1.98 1.60 3.17 Apr 3.63 1.04 3.78 7.06 1.00 7.06 0.93 1.50 1.40 May 3.54 0.52 1.84 4.74 0.52 2.46 2.84 0.58 1.65 June 3.76 0.20 0.75 3.22 0.20 0.64 1.33 0.56 0.74 July 3.48 0.11 0.38 2.39 0.13 0.31 2.64 0.13 0.34 Aug 3.72 0.16 0.60 2.75 0.09 0.25 1.12 0.06 0.07 Sept 3.49 0.10 0.35 1.05 0.40 0.42 5.44 0.08 0.44 Oct 3.56 0.27 0.96 3.57 0.27 0.96 3.53 0.27 0.95 Nov 4.41 0.43 1.90 8.82 0.35 3.09 3.87 0.45 1.74 Dec 4.07 0.60 2.44 5.96 0.70 4.17 2.74 0.51 1.40 Total 43.66 59.72 33.23 Annual Average 20.02 28.87 15.39 Percentage 45.90% 48.30% 46.30% Appendix E Specific Factors Applied for Phosphorus Loading Universal Soil Loss Equation (USLE) Parameters Erosion- Rainfall Control Erosivity (RE) Soil Erodibility Topographic Cropping Practice Factor (MJ-mm/ha-h) (K) Slope % Length (ft) Factor (LS) Factor (P) PBS Forest 125 0.15 5.5 200 0.855 0.011 1 Orchard N/A N/A N/A N/A N/A N/A N/A Cropland N/A N/A N/A N/A N/A N/A N/A Pasture N/A N/A N/A N/A N/A N/A N/A PBB Forest 125 0.17 5 200 0.758 0.011 1 Orchard N/A N/A N/A N/A N/A N/A N/A Cropland N/A N/A N/A N/A N/A N/A N/A Pasture N/A N/A N/A N/A N/A N/A N/A PBH Forest 125 0.16 3 200 0.354 0.011 1 Orchard N/A N/A N/A N/A N/A N/A N/A Cropland 125 0.18 605 150 0.917 0.003 1 Pasture 125 0.18 605 150 0.917 0.011 1 PBP Forest 125 0.18 6.1 200 0.974 0.011 1 Orchard 125 0.19 7.4 150 1.09 0.087 1 Cropland 125 0.19 6.2 150 0.861 0.003 1 Pasture 125 0.19 6.2 150 0.861 0.011 1 WBE Forest 125 0.18 6.4 200 1.04 0.011 1 Orchard N/A N/A N/A N/A N/A N/A N/A Cropland 125 0.17 2.1 150 0.237 0.003 1 Pasture 125 0.17 2.1 150 0.237 0.011 1 WBS Forest 125 0.19 10.9 200 2.201 0.011 1 Orchard 125 0.19 9.3 150 1.512 0.087 1 Cropland 125 0.21 10 150 1.68 0.003 1 Pasture 125 0.21 10 150 1.68 0.011 1 WBN Forest 125 0.19 9 200 1.66 0.011 1 Orchard N/A N/A N/A N/A N/A N/A N/A Cropland N/A N/A N/A N/A N/A N/A N/A Pasture N/A N/A N/A N/A N/A N/A N/A SPB Forest 125 0.28 12.2 200 2.62 0.011 1 Orchard N/A N/A N/A N/A N/A N/A N/A Cropland N/A N/A N/A N/A N/A N/A N/A Pasture N/A N/A N/A N/A N/A N/A N/A BFB Forest 125 0.18 8 200 1.41 0.011 1 Orchard N/A N/A N/A N/A N/A N/A N/A Cropland N/A N/A N/A N/A N/A N/A N/A Pasture N/A N/A N/A N/A N/A N/A N/A MB Forest 125 0.195 9.3 200 1.744 0.011 1 Orchard 125 0.22 11.5 150 2.07 0.087 1 Cropland 125 0.2 7.7 150 1.15 0.003 1 Pasture 125 0.2 7.7 150 1.15 0.011 1 N/A - Not Applicable (This type of land use is not within this subwatershed) K - Based on soil types within the watershed Slope - Based on soil types within the watershed Length - Based on recommendations of local Soil Conservation Service C - Based on ground cover P - Based on recommendations of local Soil Conservation Service Septic System Evaluation Parameters

No. of Septic No. Capita- Loading Systems Yrs. (kg/capita-yr) Retention PBS 0 0.0 0.65 N/A PBB 26 91.0 0.65 0.35 PBH 0 0.0 0.65 N/A PBP 6 21.0 0.65 0.4 WBE 11 38.5 0.65 0.3 WBS 0 0.0 0.65 N/A WBN 0 0.0 0.65 N/A SPB 61 213.5 0.65 0.3 BFB 0 0.0 0.65 N/A MB 0 0.0 0.65 N/A

No. of Septic Systems - Based on a count of houses within 200 meters of a pond known not to be on the town sewer system No. Capita-Yrs. - Assumes 3.5 people per household Retention - Literature coefficient based on soil type located withinthesetowns. below, whereasthecoefficientsinabovetablewereusedforallotherareasofwatershednot the residentialrunoffdirectlytoatributary.Thus,theseweightedcoefficientsareprovidedintable was donetotakeintoconsiderationthattherearenostormdrainsinHollis,AmherstandMilfordcarry and perviousareatheoveralltrappingefficiencycalculatedforeachparticularsubwatershed.This PB-3, PB-4,WB-1,WB-2,WB-3,MB-1andSB-1havebeenweightedbasedontheamountofimpervious The residentialrunoffcoefficientsforlandinHollis,AmherstandMilfordlocatedsubwatersheds N/A -NotApplicable undeveloped areasitisestimatedusingliteraturecoefficientsbaseduponthesoiltype. land use,usingtheequation:Rv=0.05+0.009(I),whereIispercentimperviousness.For Runoff coefficientsfordevelopedareasarebaseduponthepercentimperviousnessofspecified B014NANANA03 / / .801 .50.15 0.15 0.15 N/A 0.25 N/A 0.08 N/A 0.25 0.25 N/A N/A 0.15 0.15 0.25 0.15 N/A 0.25 N/A 0.15 0.15 0.15 0.15 N/A 0.25 0.35 0.184 N/A 0.191 N/A 0.15 N/A 0.15 0.15 N/A N/A 0.15 N/A N/A N/A 0.212 N/A 0.25 N/A N/A N/A N/A N/A 0.232 N/A N/A 0.25 N/A N/A N/A 0.3 N/A 0.114 72 0.123 N/A N/A N/A 0.117 0.152 N/A N/A N/A 85 N/A 0.119 N/A N/A N/A 0.113 N/A 0.134 0.124 N/A N/A N/A 0.113 65 N/A 0.122 MB 31 SPB WBN 22 WBS WBE 16 PBP PBH % ImperviousArea 0.15 0.15 0.15 N/A N/A 0.08 0.25 N/A N/A N/A 0.25 N/A N/A N/A 0.08 0.25 N/A 0.15 0.15 0.25 N/A N/A 0.698 0.25 0.15 0.35 0.15 0.15 0.815 0.15 0.25 0.698 N/A 0.815 N/A 0.15 N/A N/A 0.15 0.15 0.15 N/A N/A N/A N/A N/A N/A 0.698 N/A N/A N/A 0.329 0.25 N/A N/A N/A 0.15 N/A N/A 0.815 0.15 N/A N/A 0.815 0.248 0.194 N/A 0.25 N/A 0.3 0.698 N/A 0.698 N/A 0.248 0.08 N/A N/A 0.815 N/A N/A 0.194 0.635 0.698 0.15 N/A N/A N/A N/A 72 0.15 N/A 0.194 0.815 N/A N/A 0.194 N/A 0.248 85 N/A 0.329 0.194 N/A N/A N/A 0.635 0.329 0.194 0.248 0.329 MB 0.248 0.194 0.248 BFB N/A 65 SPB N/A N/A WBN 31 WBS WBE 22 PBP PBH 16 PBB PBS % ImperviousArea Runoff CoefficientsforSpecificLandUsesinEachSubwatershed Runoff CoefficientsforSpecificLandUsesinEachSubwatershed

Residential (>1 acre) Residential (>1 acre)

Residential (1/2-1 acre) Residential (1/2-1 acre)

Residential (<1/2 acre) Residential (<1/2 acre)

Multi-Family/Condo. Multi-Family/Condo.

Parks and Town Owned Parks and Town Owned

Commercial Commercial

Industrial Industrial

Forest Forest

Orchard Orchard

Crop Crop

Pasture Pasture Phosphorus Loading Concentrations Dissolved Sediment Attached Total Residential (>1 acre) N/A N/A 0.38 Residential(1/2-1 acre) N/A N/A 0.38 Residential (<1/2 acre) N/A N/A 0.38 Condominium N/A N/A 0.38 Parks & Town Owned N/A N/A 0.12 Commercial N/A N/A 0.20 Industrial N/A N/A 0.20 Forest 0.006 638 N/A Orchard 0.10 638 N/A Crop 0.26 638 N/A Pasture 0.25 638 N/A All values are based on literature coefficients. N/A - Not Applicable F / / / . / / N/A 0.73 N/A N/A 0.73 N/A N/A 0.51 0.66 N/A 0.59 0.73 0.9 0.6 N/A 0.51 0.66 N/A 0.59 0.85 N/A 0 0.6 0.98 N/A 0.66 N/A N/A N/A N/A N/A N/A 0.9 0.68 0.8 N/A 0.85 0.9 0 N/A N/A 0 0.9 0 N/A 0 N/A 0 0.6 0.85 N/A 0.9 N/A 0 0.05 N/A N/A 0 0 N/A 0 N/A N/A 0.7 N/A N/A 0 0.8 All othertrappingefficiencies(forforestedorparkareas)wereestimatedbasedontheslopeandlocationofland area. 0.05 0 0.05 N/A 0.5 Agriculture trappingefficiencieswerebasedonthedistanceawayfromdowngradienttributaryreceivingrunoff. N/A N/A N/A 0 N/A N/A 0 0 used toaccountfortheamountofrunoffthatwillnotmakeitatributaryorpond. 0.9 0 N/A N/A 0.95 to atributary.SinceHollis,AmherstandMilforddonothavestormdraincollectionsystem,weightedcoefficient was N/A N/A A trappingefficiencyofonewaschosenforalldevelopedareassincetheyareusuallypipedthroughstormdrainsdirectly 0 N/A 0 0 N/A 0 N/A N/A 0 one meansthatallsedimentswillbetrapped. 0 0 Trapping efficienciesarescaledzerotoone,whereindicatesthatnoneofthesediment/pollutantstrappedand N/A 0 0 0 MB 0 BFB 0 0 SPB 0 0 WBN WBS N/A WBE N/A PBP PBH PBB PBS

Residential (>1 acre)

Residential (1/2-1 acre)

Residential (<1/2 acre)

Multi-Family/Condo. Trapping Efficiencies

Parks and Town Owned

Commercial

Industrial

Forest

Orchard

Crop

Pasture Appendix F Database Search and File Review Sites Database Search and File Review Sites

Type Pollutant NH ID Site Name Site Address Town Status Permit No. @ 500 drums were buried, also a discharge of a UIC cement like material 840010 ABC MACHINE CO. 8 MANHATTAN DRIVE AMHERST backlog N/A RESIN SYSTEMS UIC Benign wastewater 840015 CORPORATION 60 ROUTE 101A (NASHUA RAMHERST backlog N/A LUST Petroleum 870558 TIFFANY SQUARE ROUTE 101A AMHERST backlog N/A CLARK BROTHERS/MERGA Volatile Organic NSER HAZWASTECompounds 890106 CORPORATION 15 COLUMBIA DRIVE AMHERST backlog N/A CLARK BROTHERS/MERGA Permit required for NSER UIC drains 890106 CORPORATION 15 COLUMBIA DRIVE AMHERST backlog N/A LUST Petroleum 890354 JASPER FARM 124 ROUTE 101-A AMHERST GW Permit GWP-890354-A HITCHNER UIC Benign wastewater 900301 MANUFACTURING 7 NORTHERN BLVD AMHERST backlog N/A NORTHERN ANALYTICAL UIC Benign wastewater 900302 LABORATORIES 3 NORTHERN BLVD AMHERST backlog N/A SOUHEGAN Wastewater disposal VALLEY system receiving COOPERATIVE SEPTIC >20,000 per day 900513 HIGH SCHOOL BOSTON POST ROAD AMHERST closed GWP-900513-A SOUHEGAN Wastewater disposal VALLEY system receiving COOPERATIVE SEPTIC >20,000 per day 900513 HIGH SCHOOL BOSTON POST ROAD AMHERST closed GWP-900513-A SOUHEGAN Wastewater disposal VALLEY system receiving COOPERATIVE SEPTIC >20,000 per day 900513 HIGH SCHOOL BOSTON POST ROAD AMHERST registration GWP-900513-A COUNTRY CLUB UIC Benign wastewater 900916 KENNEL RTE 122 AMHERST backlog N/A Database Search and File Review Sites

Type Pollutant NH ID Site Name Site Address Town Status Permit No. Permit required for roof and parking lot UIC drains 901034 KOLLSMAN 10 COLUMBIA DRIVE AMHERST backlog N/A BELLEMORE HEATING OIL CO. Willis - AST Heating oil 910623 AMHERST TEMINA 21 OLD NASHUA ROAD AMHERST ongoing N/A BELLEMORE HEATING OIL CO. FUEL Fuel oil 910623 AMHERST TEMINA 21 OLD NASHUA ROAD AMHERST backlog N/A ~300 gallons of QUINN BROTHERS LUST gasoline 910702 CORPORATION 5 CALDWELL DRIVE AMHERST closed N/A

Holding tank MOBIL OIL GAS HOLDTANKregistration, gasoline 930607 STATION 75 RTE 101A AMHERST backlog N/A Discharge of benign GRANITE STATE UIC wastewater 931015 DOG CENTER 90 RTE 101A (COBBLESTONAMHERST backlog N/A HAZWAST 840011 E UIC 840011 H & M METALS COLUMBIA DRIVE AMHERST backlog N/A permits - HAZWAST Solvents, gasoline, 840013 managemen E LUST VOCs 840013 MOORE PROPERTY 117 RT 101A AMHERST t N/A HAZWAST 890923 E UIC 890923 CUES 14 CALDWELL DRIVE AMHERST backlog N/A Permit required for water from cooling loop discharged to UIC roof drain 901033 PLASTI-CLIP CORP. 11 COLUMBIA DRIVE AMHERST backlog N/A Permit required for non-sanitary wastewater from wave soldering process to on-site UIC leachfield 901038 ITRONICS 11 COLUMBIA DRIVE AMHERST backlog N/A Database Search and File Review Sites

Type Pollutant NH ID Site Name Site Address Town Status Permit No. CLARK BROTHERS 901101 EQUIPMENT backlog / UIC / LUST Petroleum 901101 STORAGE 5 MANHATTEN DRIVE AMHERST closed N/A WOODMONT UIC Benign wastewater 881208 ORCHARDS SOUTH MERRIMACK ROADHOLLIS backlog N/A Heating oil, DAVID ROTH OPUF residential 940915 RESIDENCE 180 WHEELER RD. HOLLIS backlog N/A permits / MERRIMACK managemen HAZWASTEChlorinated VOCs 840382 METALS RT 101A MERRIMACKt N/A MERRIMACK WELL #6 (VILLAGE H2O HAZWASTEChlorinated VOCs 861101 DISTRICT) OFF MILFORD RD MERRIMACKWickson N/A LOCKHEED SANDERS MER 12 UIC Benign wastewater 920907 FACILITY 130 DANIEL WEBSTER HYWMERRIMACKregistration N/A Site evaluation, not an indication of SITEEVAL pollution 921001 MCDONALDS RT 101A/NATICOOK RD-0 MMERRIMACKbacklog N/A Heating oil, MAHON OPUF residential 930822 RESIDENCE 31 NATICOOK RD MERRIMACKclosed N/A POST ROAD PLAZA HAZWASTEtetrachloroethene 940966 SITE ROUTE 101A MERRIMACKWickson N/A CONNELL LUST Petroleum 941134 SHOPPING PLAZA RTE 3 MERRIMACKBerry N/A RODERICK SPILL/RLS oil spill 900726 RESIDENCE 49 OVERLOOK WAY, LEISUMILFORD closed N/A PENNICHUCK UIC Benign wastewater 840408 WATER WORKS MANCHESTER STREET NASHUA backlog N/A DEMERS TRUCK LUST Petroleum 870268 CENTER 635 AMHERST STREET NASHUA closed N/A AST Petroleum 880316 COCA-COLA 600 AMHERST STREET NASHUA Willis N/A LUST Petroleum 880316 COCA-COLA 600 AMHERST STREET NASHUA closed N/A Database Search and File Review Sites

Type Pollutant NH ID Site Name Site Address Town Status Permit No. permits- SULLIVAN TIRE managemen UIC Benign wastewater 880920 (ADJACENT TO 7-11) 369 AMHERST STREET NASHUA t N/A OWENS- BROCKWAY LUST Petroleum (TPA) 881101 PLASTICS OFF CELLU DRIVE NASHUA closed N/A PSNH FACILITY - LUST Petroleum 890930 NASHUA 370 AMHERST STREET NASHUA backlog N/A permits- QUIK MART managemen LUST gasoline 910341 (#30290) 496 AMHERST STREET NASHUA t GWP-910341-N

Permit for stormwater discharge CONTAINER UIC to a retention pond 910817 RECOVERY CORP 12 CELINA AVENUE NASHUA backlog N/A ASA bromodichloromethe INTERNATIONAL HAZWASTEne, chloroform 930507 COMPANY 615 AMHERST ST NASHUA closed N/A STABILE/22 LUST Petroleum 940213 COTTON RD 22 COTTON RD NASHUA backlog GWP-940213-N SOUTHLAND LUST Petroleum 890601 CORPORATION 361 AMHERST STREET NASHUA backlog N/A

permits- 880920/ SULLIVAN TIRE managemen GWP-880920-N LUST/ LUSTPetroleum 890601 (ADJACENT TO 7-11) 369 AMHERST STREET NASHUA t/ backlog GWP-880920-N New Hampshire RCRA List

Facility ID Number Name / Address

NHD088584214 NH Vocational Technical College 505 Amherst Street Nashua NHD986487205 Nicks Exxon Service Station 219 South Daniel Webster Highway Nashua NHD0010082304 Nim Cor Inc. 575 Amherst Street Nashua NHD069906352 Norge Village Amherst Street Nashua NHD986469237 Micro Vesicular Systems Inc. 22 Cotton Road Nashua NHD986472447 Micro Vesicular Systems Inc 20 Cotton Road Nashua NHD981891062 Midas Muffler 518 Amherst Street Nashua NHD982763690 Kawasak East 421 Amherst Street Nashua NHD000791178 Kollsman 3 Capitol Street Nashua NHD000791731 Kollsman 8 Capitol Street Nashua NHD980523682 Kollsman MC DTV 460 Amherst Street Nashua NHD980668859 Lockheed Sanders Inc 460 Amherst Street Nashua NHD986466290 M TEK Inc 22 Tanguay Ave Nashua NHD040231367 Itek Composition Systems Division 34 Cellu Drive Nashua NHD981065915 Gyrex Corp 472 Amherst Street Nashua NHD986471217 Hall J Lawrence Co Inc 10 Cotton Road Nashua

NHD982746901 GIS Graphics of Nashua 472 Amherst Street Nashua NHD146673785 Gate City Collision Center 561 Amherst Street Nashua NHD982746661 Getty Petroleum Corp 483 Amherst Street Nashua NHD982202749 Greased Lightning Inc 504 Amherst Street Nashua NHD050397959 Field Precast Corp Tanguay Ave Nashua NHD986466647 Digital Equipment Corp Cotton Road Nashua NHD066754151 Coca Cola USA 600 Amherst Street Nashua NHD189567761 Builders Square 420 Amherst Street Nashua NHD001084979 Beazer East Inc 2 Hills Ferry Road Nashua NHD986471266 Alden & Brodan Corp 472 Amherst Street Unit 22 Nashua NHD500014501 Anderson Sonny Automotive 537 R Amherst Street Nashua NHD986466639 Anheuser Busch Recycling Corporation 12 Celina Drive Nashua NHD986469260 Antons Cleaners 379 Amherst Street Nashua NHD986473544 ATC Power Systems Inc 472 Amherst Street Unit 12 Nashua NHD500011390 VIP Discount Auto Center 714 Milford Road Merrimack NHD045052206 Robinson Laboratories Rte 101A Jenney BLDG Amherst NHD980731319 Specialty Coating Systems Inc 13 Columbia Drive Bay 3 Amherst NHD986466431 Route 101A Auto Body 110 Route 101A Amherst

NHD981072762 Surewood Excavation 99 Milford Road Amherst NHD103707782 Teksource Inc 105 Milford Road Amherst NHD073968778 Towne Lyne Foreign Motors Rte 101A Amherst NHD092061910 Vibrac Corp 16 Columbia Drive Amherst NHD980734000 Waveonics Rte 101A Amherst NHD058540519 Wilderness Outfitters & Marine Rte 101A Amherst NHD982201048 Robinson Laboratories 1 Tanguay Street Nashua NH5986485381 Saturn of Nashua 635 Amherst Street Nashua NHD986483063 Stabile HJ & Son Inc 22 Cotton Road Unit 1 Nashua NHD980670301 Sunnyside Acura 482 Amherst Street Nashua NHD982750762 TST Equipment Co 18 Tanguay Avenue Nashua NHD98215455 Tiffany Cleaners Inc 650 Amherst St Nashua

Appendix G Buildout Phosphorus Loadings In-pond Concentrations and Parameters for Agricultural Buildout with Conservation Stump Pond Pennichuck Pond Holts Pond Bowers Pond Harris Pond Supply Pond Lake area (km2) 0.08 0.23 0.09 0.37 0.32 0.06 Mean Depth (m) 1.52 1.52 1.22 1.83 4.08 3.60 Watershed area (km2) 6.14 17.38 57.35 64.57 71.17 72.78 Precipitation volume (10^6 m3) 0.09 0.25 0.10 0.41 0.35 0.07 Evaporation volume (10^6 m3) 0.05 0.13 0.05 0.21 0.18 0.04 Precipitation loading (kg/yr) 9 26 10 41 35 7 Land use phosphorus loadings (kg/yr) 420 2409 3099 634 1175 356 Land & precipitation phosphorus loadings (kg/yr) 430 2435 3109 676 1210 363 Phosphorus loadings from Merrimack River (kg/yr) 0 0 0 177 0 0 Phosphorus loadings from preceding pond(s) (kg/yr) 0 0 1224 3124 2413 1169

Total phosphorus loadings (kg/yr) 430 2435 4333 3977 3623 1533 Stream runoff (m/yr) 0.509 0.509 0.509 0.543 0.540 0.293

Lake volume (10^6 m3) 0.13 0.35 0.11 0.68 1.29 0.23 Detention time (years) 0.04 0.04 0.00 0.02 0.03 0.01 Volumetric waterload (10^6 m3/yr) 3 9 29 36 39 21 Total P-in (mg/l) 0.132 0.264 0.148 0.111 0.093 0.072 In-pond Phosphorus (mg/l) 0.066 0.109 0.107 0.068 0.056 0.053 P leaving pond (kg/yr) 214 1010 3124 2413 1169 N/A

Buildout Phosphorus Loadings -w-conservation, Ag. In-pond Phosphorus Loadings for Residential Buildout PBSPBBPBH PBP WBE WBS WBN SPB BFB MB Total lbs/yr lbs/yr lbs/yr lbs/yr lbs/yr lbs/yr lbs/yr lbs/yr lbs/yr lbs/yr lbs/yr Land Use Residential (>1 acre) 0 450 550 1151 617 982 306 613 0 795 5463 Residential (1/2 - 1 acre) 143 229 0 0 0 359 264 0 68 216 1279 Residential (<1/2 acre) 1198 430 00000016201790 Parks and Town Owned 0 0 0 11 00000616 Commercial 20 42 487 6 285 52 0 46 112 0 1050 Industrial 1621 919 1186 104 898 0 118 0 902 486 6234 Forest 00000000000 Orchard 00000000000 Crop 00000000000 Pasture 00000000000 Septic 0 85 0 18 0 0 0 253 0 0 356 Precipitation 121 81 0 56 0 0 0 21 0 0 278 3102 2236 2223 1346 1800 1392 688 932 1244 1502 16465 Percent Phosphorus Contribution 19% 14% 14% 8% 11% 8% 4% 6% 8% 9%

ResidentialBuildout Phosphorus Loadings In-pond Concentrations and Parameters for Residential Buildout Stump Pond Pennichuck Pond Holts Pond Bowers Pond Harris Pond Supply Pond Lake area (km2) 0.08 0.23 0.09 0.37 0.32 0.06 Mean Depth (m) 1.52 1.52 1.22 1.83 4.08 3.60 Watershed area (km2) 6.14 17.38 57.35 64.57 71.17 72.78 Precipitation volume (10^6 m3) 0.09 0.25 0.10 0.41 0.35 0.07 Evaporation volume (10^6 m3) 0.05 0.13 0.05 0.21 0.18 0.04 Precipitation loading (kg/yr) 9 26 10 41 35 7 Land use phosphorus loadings (kg/yr) 413 1266 3211 778 1296 376 Land & precipitation phosphorus loadings (kg/yr) 423 1292 3222 819 1331 383 Phosphorus loadings from Merrimack River (kg/yr) 0 0 0 177 0 0 Phosphorus loadings from preceding pond(s) (kg/yr) 0 0 849 2960 2404 1198

Total phosphorus loadings (kg/yr) 423 1292 4071 3957 3735 1581 Stream runoff (m/yr) 0.509 0.509 0.509 0.543 0.540 0.293

Lake volume (10^6 m3) 0.13 0.35 0.11 0.68 1.29 0.23 Detention time (years) 0.04 0.04 0.00 0.02 0.03 0.01 Volumetric waterload (10^6 m3/yr) 3 9 29 36 39 21 Total P-in (mg/l) 0.129 0.140 0.139 0.111 0.096 0.074 In-pond Phosphorus (mg/l) 0.065 0.069 0.101 0.067 0.057 0.054 P leaving pond (kg/yr) 211 638 2960 2404 1198 N/A

Buildout Phosphorus Loadings, Res. In-pond Phosphorus Loadings for Agricultural Buildout PBS PBB PBH PBP WBE WBS WBN SPB BFB MB Total lbs/yr lbs/yr lbs/yr lbs/yr lbs/yr lbs/yr lbs/yr lbs/yr lbs/yr lbs/yr lbs/yr Land Use Residential (>1 acre) 0 450 385 0 20 607 287 609 0 0 2357 Residential (1/2 - 1 acre) 143 229 0 0 0 359 264 0 68 216 1278 Residential (<1/2 acre) 1198 430 00000016201790 Parks and Town Owned 0 0 0 11 00000616 Commercial 20 42 487 6 285 52 0 46 112 0 1050 Industrial 1621 919 1186 104 898 0 118 0 902 486 6234 Forest 00000000000 Orchard 0 0 0 1173 0 955 0 20 0 3555 5702 Crop 0 0 92 0 321 0 14 0 0 0 427 Pasture 00000000000 Septic 0 85 0 18 0 0 0 253 0 0 356 Precipitation 121 81 0 56 0 0 0 21 0 0 278 3102 2236 2150 1368 1523 1973 682 948 1244 4262 19487 Percent Phosphorus Contribution 16% 11% 11% 7% 8% 10% 4% 5% 6% 22%

AgriculturalBuildout Phosphorus Loadings Phosphorus Loadings from Residential with Conservation PBS PBB PBH PBP WBE WBS WBN SPB BFB MB Total lbs/yr lbs/yr lbs/yr lbs/yr lbs/yr lbs/yr lbs/yr lbs/yr lbs/yr lbs/yr lbs/yr Land Use Residential (>1 acre) 0 358 510 1096 604 967 306 613 0 748 5201 Residential (1/2 - 1 acre) 115 125 0 0 0 359 264 0 68 216 1147 Residential (<1/2 acre) 1080 418 00000012601623 Parks and Town Owned 000700000613 Commercial 20 42 423 6 285 52 0 46 112 0 987 Industrial 1569 774 881 104 898 0 118 0 798 486 5628 Forest 274621001325 Orchard 00000000000 Crop 00000000000 Pasture 00000000000 Septic 0 85 0 18 0 0 0 253 0 0 356 Precipitation 121 81 0 56 0 0 0 21 0 0 278 2906 1889 1819 1293 1789 1379 688 932 1106 1458 15258 Percent Phosphorus Contribution 19% 12% 12% 8% 12% 9% 5% 6% 7% 10%

ResidentialBuildout Phosphorus Loadings -w-conservation In-pond Concentrations and Parameters for Residential Buildout with Conservation Stump Pond Pennichuck Pond Holts Pond Bowers Pond Harris Pond Supply Pond Lake area (km2) 0.08 0.23 0.09 0.37 0.32 0.06 Mean Depth (m) 1.52 1.52 1.22 1.83 4.08 3.60 Watershed area (km2) 6.14 17.38 57.35 64.57 71.17 72.78 Precipitation volume (10^6 m3) 0.09 0.25 0.10 0.41 0.35 0.07 Evaporation volume (10^6 m3) 0.05 0.13 0.05 0.21 0.18 0.04 Precipitation loading (kg/yr) 9 26 10 41 35 7 Land use phosphorus loadings (kg/yr) 413 1222 2994 634 1175 356 Land & precipitation phosphorus loadings (kg/yr) 423 1248 3004 676 1210 363 Phosphorus loadings from Merrimack River (kg/yr) 0 0 0 177 0 0 Phosphorus loadings from preceding pond(s) (kg/yr) 0 0 833 2813 2260 1129

Total phosphorus loadings (kg/yr) 423 1248 3837 3666 3470 1493 Stream runoff (m/yr) 0.509 0.509 0.509 0.543 0.540 0.293

Lake volume (10^6 m3) 0.13 0.35 0.11 0.68 1.29 0.23 Detention time (years) 0.04 0.04 0.00 0.02 0.03 0.01 Volumetric waterload (10^6 m3/yr) 3 9 29 36 39 21 Total P-in (mg/l) 0.129 0.135 0.131 0.103 0.089 0.070 In-pond Phosphorus (mg/l) 0.065 0.067 0.096 0.063 0.054 0.052 P leaving pond (kg/yr) 211 621 2813 2260 1129 N/A

Buildout Phosphorus Loadings -w-conservation, Res. In-pond Phosphorus Loadings from Agricultural Buildout with Conservation PBSPBB PBH PBP WBE WBS WBN SPB BFB MB Total lbs/yr lbs/yr lbs/yr lbs/yr lbs/yr lbs/yr lbs/yr lbs/yr lbs/yr lbs/yr lbs/yr Land Use Residential (>1 acre) 0 358 369 0 20 601 287 609 0 0 2242 Residential (1/2 - 1 acre) 115 125 0 0 0 359 264 0 68 216 1147 Residential (<1/2 acre) 1080 418 00000012601623 Parks and Town Owned 000700000613 Commercial 20 42 423 7 285 52 0 46 112 0 987 Industrial 1569 774 881 104 898 0 118 0 798 486 5628 Forest 272611001322 Orchard 0 0 0 1118 0 939 0 20 0 3342 5418 Crop 0 0 79 0 314 0 14 0 0 0 407 Pasture 00000000000 Septic 0 85 0 18 0 0 0 253 0 0 356 Precipitation 121 81 0 56 0 0 0 21 0 0 278 2906 1889 1755 1315 1517 1951 683 948 1106 4052 18121 Percent Phosphorus Contribution 16% 10% 10% 7% 8% 11% 4% 5% 6% 22%

AgricultureBuildout Phosphorus Loadings -w-conservation Appendix H Model Bylaws

Appendix I Cohen Bill

References

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Acknowledgments

The preparation of this plan required the contribution of information from many sources. From Pennichuck Water Works Corporation, substantial information and assistance was received from Mr. Don Ware, Mr. Bernard Rousseau, Gary Tetley and Steve Densberger, among others. Considerable information also came from the six communities in the watershed. The names of those contributing information are listed below.

Tom Falk Bob Courage UNH Milford Public Works

George Hastings / Katie Bramley Linda Bretz NH Granitnet Nashua Conservation Commission

Pierce Rigrod Linda Wilson Nashua Regional Planning Commission Merrimack Conservation Commission

Helen Castles Vaughn Pitman Soil Conservation Service Hollis Conservation Commission

Pat Wilcox and Ariel Parent Robert Walsh NH Department of Environmental Services Milford Conservation Commission

Richard Crocker Lorraine Carson Amherst Highway Department Milford Conservation Commission

Art Kid Nashua City Engineer Community Development Information: Amherst: Karin Elmer John Harvey Nashua: Michael Yeomans Amherst Conservation Commission Merrimack: Linda Wilson Hollis: Brenda Morse Chip Chesley Milford: Bill Parker Merrimack Public Works

Bruce Moreau Key CEI Staff: Merrimack Highway Division Eileen Pannetier, Project Manager Rebecca Balke, Project Engineer Jeff Babel Cynthia Rainville, Staff Engineer Supervisor of Public Works, Hollis Charles Fuller, Hydrologic Analysis Jennifer Howald, Stormwater Monitoring Arthur Leblanc Karen Blake, Final Report Director of Public Works, Hollis

Mario Leclerc Milford Sewer Department Thank you to all who contributed.