## Facts

- David K. Armstrong and Mary Jane Armstrong owned residential property north of Lake Avenue in Rahway, New Jersey; the Klemps owned adjoining downstream property along the same stream.
- A small natural stream rose on an upstream tract and flowed north under Lake Avenue through a box culvert, then across the Armstrong and Klemp properties into Milton Lake.
- Francis Corporation developed an upstream subdivision (“Duke Estates”) and installed an integrated drainage system of streets, gutters, ditches, culverts, and catch basins.
- The system discharged into a corrugated iron pipe laid below the former streambed and covered with fill, eliminating visible evidence of the natural channel on the development tract.
- The drainage plan increased and concentrated the flow reaching the natural channel north of Lake Avenue by collecting runoff from the development and additional acreage and by collecting percolating groundwater through pipe joints designed to receive it.
- Downstream, where the stream remained largely natural, the increased and concentrated flow caused recurrent flooding and erosion, cutting into the Armstrongs’ land and damaging the Klemps’ culvert and threatening their septic system.
- The Armstrongs sued for injunctive relief; Francis filed a cross-claim against the Klemps, who also sought relief against Francis.
- The Chancery Division ordered Francis to extend the pipe or otherwise correct the condition to prevent further damage and granted similar relief to both downstream owners; Francis appealed, and the state supreme court took the case directly.

## Issues

1. What rule governs a landowner’s alteration of surface-water drainage that increases and concentrates flow onto downstream land: the common-enemy rule, the civil-law rule, or a reasonable-use standard?
2. Under the governing standard, was Francis’s drainage design an unreasonable interference that made it liable for downstream erosion and damage?
3. Was injunctive relief requiring corrective drainage measures an appropriate remedy?

## Decision

- The court affirmed the decree requiring Francis to correct the drainage condition to prevent continued downstream harm.
- The court rejected an absolute common-enemy approach and adopted a reasonable-use doctrine for surface-water drainage disputes in New Jersey.
- Applying reasonable use, the court held Francis’s conduct unreasonable because it foreseeably and substantially increased and concentrated flow (including collected groundwater), causing continuing damage downstream.
- The court upheld granting relief to both the Armstrongs and the Klemps and declined to shift responsibility away from Francis through the cross-claim.

## Legal Principles

- A landowner may make only reasonable changes in the natural drainage of surface waters; liability turns on reasonableness under all the circumstances.
- Reasonableness is assessed by weighing factors including the gravity and foreseeability of harm, the utility of the actor’s conduct, and the availability, practicality, and cost of measures that would avoid or reduce harm.
- Social utility of land development does not justify imposing substantial, avoidable drainage harms on neighboring properties; the actor who increases drainage burdens may be required to bear the cost of protective or corrective measures.
- Equitable relief may require an upstream developer to implement engineering corrections (such as extending drainage infrastructure) to prevent continuing erosion and flooding.

## Conclusion

The court replaced rigid surface-water rules with a reasonable-use standard and held that an upstream developer who engineered a substantial, foreseeable increase and concentration of drainage onto downstream land is responsible for corrective measures to prevent continued damage.


Armstrong v. Francis Corp., 20 N.J. 320, 120 A.2d 4 (N.J. 1956)