.: - )10 Public Disclosure Authorized ENVIRONMENTAL IMPACT ASSESSMENT OF ZONKWA DAM DRAFT REPORT Public Disclosure Authorized Public Disclosure Authorized Public Disclosure Authorized , 1'\ KADUNA STATE WATER BOARD , KADUNA STATE FEDERAL REPUBLIC OF NIGERIA . .. ENVIRONMENTAL IMPACT ASSESSMENT OF ZONKWA DAM. DRAn' REPORT JUNE. 1991 ABUCONS (NIC) LIMITED Ahmadu Bello University Consultancy Services Ahmadu Bello University Zaria Nigeria CONTE~"S • PAGES .' EXECUT'IVE SlJ!ftiARy •••••••••••••••••••••••••••••••••••••• 1 1. Environmental Regulation ••••••••••••••••••••••••••• 2. Project Description •••••••••••••••••••••••••••••••• :: 7 3. Baseline Data •..••••...•••••••••••...••••.••••..... 12 4. Analysis of Alternatives ••••••••••••••••••••••••••• 30 5. Environmental Impacts ••••••••••••••••••••••••••••••• 32 6. Mitigation Plan .•.•••••..•••.•••••••••••.•...••.•... 57 7. Monitoring Plan ••.••••.•.••••.•••••.••••.•••••....•. 62 8. Appendix i) Terrestrial flora ........................... 64 ii) Wildlife of the reservoir area ••••••••••••••• 67 iii) Non-woody plants of the reservoir area ••••••• 68 iv) Cultivated plants of the reservoir area •••••• 69 v) Medicinal plants of the reservoir area ••••••• 70 vi) Algae of the Zonkwa Dam Project area ••••••••• 71 vii) Instrumentation and Monitoring Guidelines Directory.................................... 74 viii) Maintenance guidelines directory............. 75 ix) List of preparers •••••••••••••••••••••••••••• 76 x) List of persons contacted •••••••••••••••••••• 77 xi) References ••••••••••••••••••••••••••.•••...•• 79 xii) Record of interagency/forum meetings ••••••••• 80 1 EXECL~IVE SUMMARY , 1. The Kaduna State Water Board (KSWB) wishes to undertake the improvement of water supply to Zonkwa. The project includes the construction of a dam. treatment works and distribution system. It is to be financed by a loan taken by the Federal Government of Nigeria from the World Bank. One of the conditionalities for eligibility for a loan requires the Water Board to undertake through environmental inpact assessment of the project. in accordance with the World Bank guidelines. 2. Zonkwa town, Zangon Kataf and surrounding villages have had no public pipe borne water supply scheme. To OVercome this, a water supply system was designed in 1976 by Engineering and Consulting Associates (Nig) Limited, Kano (ECAN). After some modifications of the design of the treatment plant, tender documents were prepared and the contract for construction was awarded. Civil works for Kaduna State Water Board offices and colony at treatment plant location have been executed by a local contractor and town pipelines have been laid by direct labour. The contract to supply and erect the treatment plant on modified design basis was signed in March. 1983. Due to lack of funds the execution of all works was stopped in 1984. An emergency water system and treating borehole water was proposed in 1989. KSWB tried to commence the project but without much success. In 1991 Water and Power Development Company Limited. Kaduna (WAPDECO) produced a Final Report on Rehabilitation Study of ZonkwA Water Supply Scheme. 2 3. The consultants adjusted the previously accepted scheme and its modified treatment plant to meet actual requirements. Furthermore, nltcrnntive system concerning Zonkwa township water supply only, were lnvcatlglltcd. In all (our schemes were considered: Phase 1 Alternative 1; Phase 1 Alternative 2; Phase 2 Alternative 1 and Phase 2; Alternative 2. Phase 1 is for the year 1990. while Phase 2 is for the year 2005. Alternative 1 is for the entire sheme (Zonkva town, Zangon-Kataf and surrounding villages) while Alternative 2 is for Zonkwa township water supply only. The consultants have recommended the Phase 1 Alternative 2 scheme. 4. The scheme consists of placing a zoned earthfill dam with concrete diaphragm on river Kwasau at Zonkwa. This alternative follows more economic considerations. and requires less investment cost for a supply system to Zonkwa township. Water is pumped from Zonkwa reservoir via 300mm raw wnter pump main to the treatment plant. After treatment the water is pumped via 300mm treatment pumping main to the 150Om' ground reservoir on Zonkwa Hill. From there the water is delivered to Zonkwa town via 2400m long gravity main. 5. An environmental Assessment of anticipated or expected environmental effects and impacts of the dam has been made. Specific impacts are classified as either positive or negative and assessed. Mitigation mc~surcs nre identified and mitigation plans to reduce potentially significant adverse effects to acceptable levels are proposed. 6. The study shows that the positive impacts are: (i) The site for the proposed project was acquired by the KSWB in 1980, full compensation has been paid to the 3 landowners and farmers, the acquired ares has been ­ demarcated and since there are no settlements within the acquired area. it would not incure any resettlement costs. (ii) The dam has po.tential for multi-purpose use such as: Water supply. irrigation. fisheries and recreation. In the design of the consultants, allowance was only made for domestic. industrial and livestock uses. Based on the projected raw water demand for Zonkwa town only (in the year 2040) of 2.56 x 106m3 and Dam operational storage 6 3 capacity of 2.8 x 10 m , it is estimated that the reservoir can sustain an irrigation project area of about 13 h~ctares. (iii) Zonkwa town and the surrounding villages have no pipe borne water supply. The project would ensure adequate and reliable water supply. It would also improve the sanitary conditions of the town and reduce the incidences of SOme of the water borne and water related diseases e.g­ dysentry, diarrhoea, typhoid. (iv) The project would cause an improvement in the local economy during the construction and as well as the operation stages by providing employment opportunities. By attracting the establishment of small and medium scale • processing and manufacturing industries it would improve the local economy and provide more job oppurtunities. 4 The availability of greater and more reliable source of water would encourage the development of larger land area for irrigation pruposes thus increasing not only agricultural production but ensuring more abundant and all the year round availability of vegetable crops. The development of fish within the lake would not only be a source of income but also as an alternative source of protein. 7. Among the negative impacts of the Zonkwa dam are: (i) Short term loss of agricultural land by the impoundment of water in the reservoir area of 102 hectares. ii) Disturbance of biota within the inundated area. However none of the plant nor animal species is an endangered species as they are the normal entities within the savannah region. iii) Malaria is already endemic in the area. There is a likelihood that the impoundment of water behind the dam would cause an increase in the incidence of the disease. 8. The possible mitigation measures to the negative impacts are: i) Afforestation of the reservoir rim to encourage the ~ecovery of the biota. Possible trees to be planted should be evergreen trees of economic value. ii) Seeding the reservoir with fingerlings of tilapia and mud fish to control tbe population of tbe mosquito larvae. 9. Necessary measures to improve the environmental quality of the area are: 5 i) Rehabilitation and proper organization of the facilities for the disposal of waste water solid wastes and storm water runoff to prevent the pollution of the reservoir. ii) Regrassing and offorestation of the valley slopes to minimize erosion and sedimentation of the reservoir. iii) Encouragement of good agricultural practices such as contour tillage, proper use and management of fertilizers and pesticides to minimize any harmful environmental impacts on the lake• • 10. Measures to minimize social conflict within the area should include: i) Demarcation and the establishment of grazing tracks leading to possible watering sites around the reservoir rim. i1) Fencing of farmlands along the grazing tracks to prevent livestock encroachment. iii) As an alternative to lOCi) watering points can be provided downstream of the bridge to avoid contamination of the reservoir by animal droppings and prevent livestock encroachment of formlands around the reservoir. 6 1.0 POLICY, LEGAL AND ADMINISTRATIVE FRAME WORK Kaduna state 1s vishing to undertake the Zonkwa Water Supply Scheme. The project is to be financed through a loon the Feder"l Government of Nigeria is expecting to take from the World Bank. To be eligible to benefit from the said loan. the World Bank has requested the Kaduna State Water Board to undertake a thorough assess­ ment of the Environmental Impact of the proposed Zonkwa Dam on the environment. This assessment viII then satisfy the recommendations of the Nigerian Federal Environmental Protection Agency (FEPA); and the Operational Directive 4.00 of the World Bank. 7 2.0 PROJECT DESCRIPTION 2.1 TECHNICAL ASPECTS Underground water supply for Zonkwa town is not feasible because the underlying basement complex rocks are poor in groundwater yield. In addition, there is the probability of pollution of the groundwater by seapage from pit laterins. The best options for the supply of potable water for the inhabitants is therefore by harnessing stream flow. The Zonkwa environ is hilly and dissected by drainage channels many of which lie in deep gorges suitable for the creation of dams. In a survey, various sites were found favourable. However, the present