Climate change is a reality. It is impacting life and support systems on earth. It is a formidable challenge faced by human beings in recent times and is impacting holistically ecological processes in lithosphere, hydrosphere, atmosphere and cryosphere. Hydrosphere, in particular the freshwater ecosystem has relatively been impacted more. Kalpani ecosystem being an urban stream and life line of Mardan and Nowshera districts has been rendering invaluable ecological services. It has been subjected to every sort of use and abuse and so profoundly exhibits the impacts of climatic changes. The impact, of climatic changes primarily variation in temperature and precipitation influencing the water discharge, on PCFs and fish fauna was investigated in detail from February 2007 to November 2008. To assess and evaluate the impact of climatic changes Kalpani stream was divided into 10 zones. Standard materials and methods were adapted for fish sampling, water sampling and data analysis. Sampling resulted in collection of 31 fish species belonging to 9 families. The fish species caught were grouped as per the research design into: Cyprinid - Crossocheilus latius, Tor putitora, Baralius modestus, Baralius vagra, Baralius pakistanicus, Puntius chola, Puntius Ticto, Puntius sophore, Puntius terio, Puntius vittatus, Salmostoma bacaila, Garra gotyla, Labeo dyocheilus, Labeo dero, Aspidoparia morar, Danio devario, Chela laubuca, Carassius auratus; and, Non Cyprinid - Triplophysa naziri, Schistura microlabra, Acanthocobitis Heteropneustes fossilis, botia, Mystus Oreochromis bleekeri, mossambicus, Mystus cavasius, Channa punctata, Glyptothorax naziri, Glyptothorax punjabensis, Ompok pabda, and Mastacembelus xxiarmatus. Water sampling for 21 pxxiiysicochemical factors (PCFs) was carried out. To establish relationship between fish species and PCFs data was subjected to statistical analysis using Minitab 14 and CANOCO 4.5 computer software. To draw future scenario of water discharge data was extrapolated to generate scenario of 2025 using cftool of matlab computer software. Under the winter scenario most number of Cyprinid fish (39.18%) were caught in zone 10, followed by zone 9 (24.75%) with less number of fish caught (0.68%) in zone 3 and 5, while under summer scenario most numer of Cyprinid fish were caught (32.03%) in zone 10 followed by zone 9 (13.94%). Under winter scenario most number of non Cyprinid caught were caught in zone (35%), followed by zone 9 (23.75%), no fish was caught in zones 4, 5 and 6, while under summer scenario most numner of non Cyprinid fish caught were from zone 10 (32.21) followed by zone 9 (20.52) while in zones 3 and 4 less number of fish (1.04 in each) were caught. The results reveal that fish biodiversity and catch increases from north to south with maximum found in Risalpur and Nowshera zones alluding to optimum environmental conditions. Tor putitora a fish of high commercial value was found in all the zones, any improvement either at species level or population level of Tor putitora would be an indication of improvement in the environmental conditions of Kalpani. The results suggested that parameters like temperature, DO, altitude, turbidity and TSS have direct impact on the assemblages‘, composition, abundance and distribution of fish species. The regression analysis of intrarelationship suggested that Temperature, DO, altitude, total hardness, sulphates, conductivity, Fe and Ni, and Zn; Turbidity, conductivity xxiiand TSS had strong intrarelationship and significantly reduc lethality of pH. The degraded surface water values are close to threshold values of WHO and NEQS for Pakistan. In comparison to the study conducted by IUCN, (1994) the stream has deteriorated to a very high degree; results of heavy metals results were devastating. DO showed improvement in its status plausible reason for which could be the flash floods occurring since mid 1990s. The species environment relationship had been explained through Canonical correspondence analysis (CCA). The first two axis of the CCA ordination i.e. CC1 and CC2 explains the species-environment relationship clearly and accounts for 77.9% of the variation in the weighted average of 19 Cyprinid fish species with respect to summer environmental variables and 80.37% for Non Cyprinid. The first two axis of the CCA ordination i.e. CC1 and CC2 explains species-environment relationship clearly and accounts for 77% of variation in the weighted average of 19 Cyprinid fish species with respect to environmental variables and 76.6% for Non Cyprinid under winter scieario for example. The water discharege projections suggest that in 2025 Kalpani freshwater ecosystem would experience increase in the duration of very low flows due to variation in precipitation in view of increase in global warming, the fish fauna would be facing local extinction e.g., the endemic fish species with weak tolerance range in response to certain environmental factors. The overall fish production may not drop appreciably but the diversity would be low. To verify the results of future water discharge scenario met data from three meteorological stations having influence on the Kalpani stream analyzed was found consistent with the findings of the water discharge data (both current and projected). If the current trends of both meteorology and water discharge hold true then the future xxiiiscenario will be one of low flows as has been projected. Non-climatic changes like sand mining and gravel extraction operations were observed to be highly unsustainable and will have serious affect on the groundwater recharge quality of Kalpani stream and result in loss of precious habitat. Zones like Gujar Garhi, Baghdada, Hoti and Chowki Nisar are already heavily degraded, under the sand mining and gravel extraction besides pollution. Declared on the basis of scientific evidence as the 2 nd most dirty tributary of Kabul River system in 1992-93 the stream is dirtier than ever and the day is not far away when it will ecologically die under increasing natural and anthropogenic stressors unless drastic measures at the government and societal level are taken. Declared as ―biological assets freshwater ecosystems are both disproportionately rich and disproportionately imperiled‖, and on the basis of data generated and collected for the study Kalpani stream fully vindicates the statement. It can be stated with high degree of confidence that Kalpani stream is imperiled and is dying. The impacts described are based on projected GHGs that will double by the end of this century and an improvement in the situation keeping in view the track record of the parties to the Kyoto protocol seem highly unlikely. Thus, it is incumbent upon KPK to focus on adaptation strategies to protect and conserve freshwater resources based on carefully conducted targeting research program. This puts to the front that more research focused on the freshwaters is needed to enable the policy level and decisions makers to take appropriate measures to save their biological assets for future generations.